DOI: 10.3897/aca.9.e202441

Authors: Barbbara Rocha, Ignasi Arranz, Victor Saito

Abstract: Temporal stability is a fundamental property of ecological communities because it reflects their capacity to maintain structure and functioning under environmental change. A key mechanism expected to support this stability is interspecific asynchrony, in which declines in some populations are compensated by increases in others, buffering fluctuations at the community level. In freshwater fish assemblages, stability may also be reflected in the temporal consistency of community size structure, an important dimension of community organization. Understanding how these processes respond to biological invasions is essential for identifying mechanisms that sustain native communities in impacted ecosystems. Here, we evaluated the effects of invasion pressure and its temporal variability on stability in native fish communities and tested how asynchrony contributes to stability under invasion. We hypothesized that:communities exposed to higher invasion pressure would exhibit lower stability, particularly when invasion regimes were more pulsed than chronic; andasynchronous population dynamics would enhance native community stability under invaded conditions.To test these hypotheses, we analyzed 270 freshwater fish community time series from French rivers, each monitored for 10 years. We used linear models to assess relationships between invasion metrics and two response variables: community stability and the coefficient of variation of size-spectrum slopes over time. Our results showed that sites with higher mean relative abundance of non-native fishes had lower stability and greater variability in community size structure. Moreover, the negative effects of invasion pressure were stronger under more variable invasion regimes, indicating that fluctuations in non-native abundance can amplify the destabilizing effects of sustained invasion pressure. In contrast, asynchrony was positively associated with community stability, indicating that compensatory dynamics among native populations can buffer invasion effects. Together, these findings suggest that non-native fishes erode the temporal stability of native assemblages, while asynchronous dynamics help buffer community fluctuations in impacted freshwater ecosystems.

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DOI: 10.3897/aca.9.e209479

Authors: Ruth Wright, Heather Price, Ana Novoa, Katharina Dehnen-Schmutz, Aileen Mill, Zarah Pattison

Abstract: Invasive non-native species (INNS) are one of the main drivers of global biodiversity loss (I.P.B.E.S. 2019) and an important issue in the UK, one of the most nature-depleted countries on Earth (Burns et al. 2023). Understanding public awareness and perceptions is critical for successful management of INNS impacts (Crowley et al. 2017). However, measuring them using traditional methods, such as surveys, has historically been limited by financial and time constraints. Conservation culturomics - the use of digital data to assess human-nature interactions - can provide a cheap and efficient solution to these constraints (Jarić et al. 2021). Indeed, internet search volumes provide a proxy for public interest in INNS (Proulx et al. 2014). We used Google Trends to assess the relative search volumes (RSV), from 2009 to 2023, for scientific and common names of 126 INNS in the UK, taken from the Great Britain Non-Native Species Secretariat’s risk assessments and identification sheets. We found that species were more likely to be searched on Google if they were larger, offered more uses to humans, and had been resident in the UK for longer. To understand what drives RSV, we reviewed online content correlating with peaks in search interest (≥1.5 standard deviations above the mean search interest for that species). Factors influencing RSV over time included seasonal changes in the species (such as flowering periods for plants) and the appearance of the species in the media (such as television features on nature documentaries). We explored how peaks in RSV are correlated with online content, looking at types of media (blogs, social media posts, forum discussions etc.) and what topics are covered when INNS are discussed online (management, impacts, cultivation of the species, etc.). Correlations between RSV and mentions in mainstream media such as television and national news articles suggest that media engagement plays an important role in driving online interest in INNS. This growing interest is vital to ensure community understanding and support for INNS reporting, containment and eradication programmes, helping to limit biodiversity loss.

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DOI: 10.3897/aca.9.e208361

Authors: Melodie McGeoch

Abstract: Invasive alien species have become persistent features of landscapes, ecological communities and ecosystems across much of the world. In most regions the problem is expected to grow as new species continue to establish and spread. Their effects on communities are twofold - they both enrich local species richness and shift patterns of dominance. While the number of globally established alien taxa is large, the subset with evidence of negative biodiversity impact, i.e. invasive alien species (IAS), is considerably smaller, and recent work suggests that in some regions these numbers are beginning to stabilise. In the Antarctic, for example, although around 600 alien species have been introduced, mostly since 1950, recent rates of introduction are either slowing or stable. Nonetheless, local range expansion of already-established IAS continues worldwide, and their impact on biodiversity grows as a function of the area they occupy. The richness and dominance effects of alien species on local communities are distinct but can interact, together transforming community properties and function. Managing these dynamics is complicated by two challenges. First, population eradication or control is expensive and often fails. Second, under climate change it may become increasingly difficult to distinguish deliberate human introductions from natural range expansion, complicating decisions about appropriate management responses. Looking ahead, how should novel ecosystems be approached, i.e. those characterised by mixed native and alien species communities? I argue that two key tasks now face invasion biologists and ecologists: (i) applying our substantial understanding of biological invasions to guide and advocate for future-ready governance, and (ii) developing model-based forecasts of likely futures in the presence of IAS. Both tasks point toward the need to think beyond prevention and control, toward envisioning the desired qualities of natural systems and actively managing to maintain those values. The resist-adapt-direct framework and integrated environmental governance offer structured ways of approaching these policy and management challenges, while modelled trajectories of community change can inform expectations. Importantly, the rapidly growing and openly accessible knowledge base on IAS makes it increasingly feasible to forecast what ecological communities might look like fifty to a hundred years from now. Such forecasts can inform and prepare society, and support the formulation of policy that is ready for the ecological futures we are likely to face.

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DOI: 10.3897/aca.9.e202100

Authors: Pavel Pipek, Gabriel Henrique de Oliveira Caetano, Susan Canavan, Maria Loreto Castillo, Ana Sofia Cardoso, Shawan Chowdhury, Jan Čuda, Łukasz Dylewski, Paula Gervazoni, Jérôme Gippet, Theresa Henke, Alessandra Kortz, Bernd Lenzner, Stefano Mammola, Peter Mikula, Ana Novoa, Nadja Pernat, Petr Pyšek, Rubén Rabaneda-Bueno, Uri Roll, Valerio Sbragaglia, Jessica Smith, Allan Souza, Marek Šmejkal, Reut Vardi, Shengyu Wang, Ivan Jarić

Abstract: Effective conservation of biodiversity, declining at unprecedented rate, requires not only monitoring of threatened species populations but also rapid detection of new incursions of alien species. However, traditional monitoring methods are costly, and citizen-science data is often geographically biased.iEcology, i.e. harnessing online digital data generated for purposes other than science (e.g. social media posts, photos, or online search behaviour), has been proposed as a tool to fill such biodiversity data gaps, especially in underrepresented regions. Despite growing interest, the full potential of iEcology for monitoring species distributions has not been systematically assessed.We systematically reviewed studies that used iEcology methods to obtain georeferenced species observation data, with specific focus on the representation of digital platforms, taxonomic groups, ecological realms (freshwater, marine, terrestrial) and geographic regions, as well as raw data availability. As a substantial proportion of the screened & reviewed studies focused on non-native species, we additionally assessed whether any reported impact information is relevant to Gloim (Global environmental impacts of plant invasions), our new project on global invasion impacts.

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DOI: 10.3897/aca.9.e206527

Authors: Diana Carolina Albuja Carbonell, Travis Flohr

Abstract: Greenhouse experiments in invasion ecology have proven valuable for uncovering the mechanisms behind plant invasions (Ehrenfeld 2003). Their controlled environmental conditions allow researchers to isolate and examine specific ecological processes (Zanetti et al. 2020). A widely distributed invasive species in the Eastern Deciduous Forests of North America is Japanese Barberry (Berberis thunbergii), an introduced shrub known to colonize both highly disturbed and relatively undisturbed forests (Harrington et al. 2004). Feral populations of this species are commonly found in forest understories, where dense infestations hinder native plant regeneration. One of the major concerns after the removal of invasive shrubs is their potential regrowth and the difficulty of reestablishing native plant species that can successfully outcompete and control the infestation (Weidlich et al. 2020; D'Antonio and Meyerson 2002). To gain a deeper understanding into the role of native species in suppressing reinvasion, we grew the native forb Heath Aster (Symphyotrichum ericoides) together with the invasive shrub in soil collected from a forest heavily infested by Japanese Barberry, where the species relative aboundance is approximately 60% within the shrub community (Fig. 1). Our experiment is the first to examine seed germination and early growth of both species simultaneously. Additionally, the presence of other native species emerging from the soil seed bank provided key insights into the functional traits required for native competitors to more effectively outperform Japanese Barberry propagules under current and projected climate scenarios in central Pennsylvania.

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DOI: 10.3897/aca.9.e205952

Authors: Matthew Coole, Tom August

Abstract: AI and Large Language Models (LLMs) are increasingly applied to modern information processing, and ecology and biodiversity are no exception. The OneStop (2025) project seeks to minimise the introduction, establishment and spread of terrestrial invasive alien species. As part of this project, we are investigating how LLMs can accelerate the Environmental Impact Classification for Alien Taxa (2026) assessment process (Hawkins 2015).Prior work has explored smaller, locally run encoder/decoder models for EICAT impact classification (Brinner and Zarrieß 2025). We build on this by investigating whether larger, general-purpose LLMs offer greater flexibility across the full EICAT schema. Our system assists human annotators by ingesting PDF documents, converting them to a structured format, and applying LLMs to identify invasive species impacts, whilst keeping humans-in-the-loop to ensure consistency and reliability. The system extracts evidence text, EICAT classification level, impact mechanism and identifies the impacted native species.To benchmark the system, we are running an inter-annotator evaluation with 22 annotators, all of whom are scientists in the domain and around half of whom have experience applying the EICAT assessment protocol. Papers for evaluation are drawn from existing EICAT assessments in the Global Invasive Species Database (GISD). The evaluation uses a Balanced Incomplete-Block Design with a core set of papers reviewed by all annotators. Annotators are asked only to read the EICAT guidelines before starting — intentionally minimal, to help surface ambiguities in the guidelines themselves. We use Cohen's kappa (Cohen 1960) to measure pairwise agreement on impact identification and Krippendorff's alpha (Krippendorff 2011) across the full multi-label classification scheme.We also perform automated evaluation on a wider set of GISD texts, comparing single-annotator extractions against system outputs using precision, recall and F1 scoring across impact identification, mechanism and severity classification. We trial multiple LLMs via AWS Bedrock (GPT-OSS, Amazon Nova, Claude, Llama), assessing whether lower-cost models can perform as reliably as human assessors.The tool (Suppl. material 1) is brought together in a web-based portal covering the full EICAT assessment workflow. We also plan to evaluate ASReview (Schoot 2021) and LatteReview (Rouzrokh and Shariatnia 2025) to understand if they can speed up abstract screening at the literature review stage. The portal follows FAIR data principles (Wilkinson 2016) and is designed to remain available beyond the life of the OneSTOP project, either via further funding sources or as an open-source, self-hosted solution. A preliminary report will be available in July 2026, with a full cost-benefit analysis by the end of the year, providing practical guidance for organisations considering whether AI-assisted EICAT assessment is worth the investment.

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DOI: 10.3897/aca.9.e205907

Authors: Madeleine Freudenreich, Guilhem De Barros

Abstract: The INVMED-Flore platform (https://invmed.fr) was developed by the Mediterranean National Botanical Conservatory and shared with the Alpine and Corsican National Botanical Conservatories to disseminate resources and occurrence data on invasive and potentially alien plant species (IAS) in the French Mediterranean region. It is interconnected with the SIMETHIS database, a professional tool that feeds into regional and national biodiversity information systems.This database compiles more than 247,440 EVEE records, all subjected to a rigorous validation process and georeferenced across the eleven departments of southeastern France and the Corsican territory. It also integrates bibliographic data and reference frameworks covering native status, as well as biological, phenological, and ecological traits.To complement this system, management actions targeting these species are also recorded and documented. This poster will illustrate how these data are structured and made interoperable, contributing to strengthened knowledge, management practices, and collaboration dynamics surrounding invasive alien plant species in the Mediterranean region.

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DOI: 10.3897/aca.9.e205479

Authors: Joana Vicente

Abstract: Biological invasions demand prioritisation frameworks that are rigorous, adaptive and actionable. Moving beyond species-level risk ranking, contemporary approaches integrate ecological, spatial and socio-political dimensions — evaluating where invasions are likely to occur, how they spread, what impacts they can generate, and which management interventions deliver the greatest return under constrained resources. Prioritisation thus becomes a critical bridge between ecological knowledge and operational decision-making.Recent methodological advances have expanded both the scope and resolution of these frameworks. Large-scale biodiversity data, species distribution models and scenario-based forecasting now enable anticipation of invasion dynamics under changing environmental conditions. Machine learning and automated workflows enhance real-time detection and prediction updating, while integration of remote sensing, citizen science and monitoring networks extends spatial and temporal coverage. These developments also expose persistent challenges around data quality, bias and interoperability that require explicit attention.A central challenge remains translating analytical complexity into policy-relevant outputs. Effective prioritisation depends as much on clarity and transparency as on methodological sophistication — ensuring results can meaningfully inform early-warning systems, regulatory reporting and local management decisions. Participatory approaches and stakeholder co-design are essential to align scientific outputs with governance realities.Prioritisation emerges not as a static tool, but as an adaptive, iterative and scalable process embedded within governance systems, capable of navigating uncertainty and underpinning timely, evidence-based responses to one of the defining environmental challenges of our time.

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DOI: 10.3897/aca.9.e205367

Authors: Xing Chen, Tao Wang, Fengzhi He

Abstract: Many freshwater fish species, including carps, salmonids, and catfishes, have been widely introduced outside their native ranges. These introductions can lead to profound ecological consequences. Here, we assessed the environmental impacts of alien freshwater fish, including their influence on abiotic variables, native species, and ecosystem function in the introduced regions. Following the Extended Environmental Impact Classification for Alien Taxa (EEICAT) framework and associated metrics, we analyzed the impact severity and mechanisms of the records related to alien freshwater fish in the InvaPact database, which used large language models to extract and categorize environmental impacts posed by alien species. We have identified over 8000 records, covering hundreds of alien freshwater fish species observed in all continents except for Antarctic. Various negative impacts were posed on native species by alien freshwater fish through a wide range of mechanisms, with predation being the most frequently reported mechanism, followed by herbivory and competition. Moreover, more than half of these species contributed to population decline or even local extinction of at least one native species. In addition, alien freshwater fish also caused alteration of abiotic environment and fundamental ecosystem functions, leading to water quality degradation and modified food webs. Our results demonstrate the necessity of shifting from species-level monitoring toward multi-dimensional assessments that capture the complex impacts posed by alien species, which can contribute to the development of holistic management strategies.

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DOI: 10.3897/aca.9.e205165

Authors: Jean-Francois Maillard, Adrien Tableau, Alexandre Villers, Benoit Pisanu, Fabian Rateau

Abstract: Species from all major taxonomic groups are experiencing major population declines due to human-driven pressures, including habitat destruction, climate change, pollution, overexploitation, and invasive species. Islands are especially vulnerable, as they host many endemic species with small populations and limited genetic diversity, making them highly sensitive to environmental disturbance. To protect endangered species, conservation actions often focus on the most vulnerable populations through protected areas, population reinforcement, translocations, and invasive species control. Among these strategies, the eradication or control of invasive alien species (IAS) is widespread on islands. Success rates have improved in recent years, even on remote or technically challenging islands. However, removing invasive small mammalian predators remains difficult, as eradication outcomes depend on many interacting factors: technical feasibility, cost, ecological impact, social acceptability, risk of reinvasion, and species behaviour. Trapping efficiency depends heavily on ecological knowledge such as animal density, home range, and movement patterns. Behavioural traits such as trap avoidance can reduce effectiveness, especially in mustelids and other carnivores. In inhabited or poorly isolated areas, reinvasion from surrounding regions can also compromise success, particularly where short dispersal corridors exist, such as land connections.This context is especially relevant for the White-breasted Thrasher (Ramphocynclus brachyurus), a bird strictly endemic to the Caravelle peninsula in Martinique, a French Caribbean island. The species occupies about 1,000 hectares and is listed as endangered. One of its main threats is predation by the small Indian mongoose (Urva auropunctata), an introduced predator known to prey on eggs, chicks, and probably fledglings and adults. To assess whether mongoose extirpation could be considered a realistic management option, we evaluated different scenarii of control design on simulated mongoose populations by combining field data on the movement of female mongooses and litterature on their population dynamics. We captured and equipped 19 individuals from dry forest patches of the peninsula with GPS devices during the dry season, when control measures are most efficient for reducing population growth. Of these, 16 produced sufficient data to estimate their movement parameters and home ranges. These results were then mobilised to simulate the movements of a hypothetical population of females across the peninsula, to evaluate how trap spacing, trapping duration, and individual behavior regarding traps could influence eradication success. The costs associated with the different successful trapping designs were calculated to determine optimal strategies regarding cost-benefit ratio.

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DOI: 10.3897/aca.9.e205120

Authors: Mark van Kleunen

Abstract: Recent decades have seen major efforts to build databases on the distributions of native and alien species. Consequently, we now know that more than 16,000 vascular plant species have been recorded as naturalized alien species worldwide, several thousand of which are considered invasive. For alien plant, a major pathway of introduction is cultivation. A joint analysis of the first version of the World Cultivated Plants (WorldCuP) database and the Global Naturalized Alien Flora (GloNAF) database showed that global patterns of naturalization were largely explained by colonization pressure. Still, only a small proportion of the introduced species has become naturalized. Potential drivers of plant invasion success are global change factors such as climate change, eutrophication and pollution. In line with this we could show that many species that have become more common due to environmental change in their native European ranges are also expanding globally as naturalized aliens. Nevertheless, an analysis of the IUCN Red List identified 238 plant species that are threatened with extinction in their native regions but have become naturalized or invasive in other parts of the world, thereby posing interesting challenges for management. Although such macro-ecological analyses based on large databases provide major insights into potential drivers of large-scale plant-naturalization patterns and consequences, we need experiments to test the mechanisms that might give naturalized alien species an advantage over native species. In my group’s experimental work, we focus on how ecological processes that determine coexistence of plant species —particularly, competition and plant-soil feedback (i.e. the process in which plants change abiotic and biotic components of the soil, which then affects subsequent plants growing on that soil)— might be affected by various global change factors, and by the numbers of co-acting global change factors. For example, in a large experiment with five pairs of native and alien species and nine global change factors, we found that with increasing numbers of concurrent global change factors plant-soil feedback shifted from negative to neutral or positive in native species, whereas they were consistently positive and became stronger in alien species. This experiment and others suggest that many naturalized plant species take more advantage of (or suffer less from) increasing numbers of global change factors than native species do. Together, our experimental and macro-ecological studies indicate that with further global environmental change we can expect further big changes in our regional floras.

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DOI: 10.3897/aca.9.e205118

Authors: Anke Fischer

Abstract: The concept of invasive alien species seems to have successfully broadened its scope from the scientific to the policy realm: It plays an important role in the Convention on Biological Diversity, it continues to mobilise action in the EU since 2014, and also at national levels, the concept has developed significant traction - Sweden’s most recent regulation on invasive species that also restricts the spread of popular garden plants being a striking example.In this talk, I explore the discursive processes behind this seeming success, looking at ‘invasive alien species’ as an environmental policy concept, and at its development and uptake as conceptual innovation (Meadowcroft and Fiorino 2017). Meadowcroft and Fiorino (2017) postulate that three factors are crucial for a policy concept to develop traction: (a) the concept needs to address a perceived need, it needs to fill a niche, (b) the concept needs to be sufficiently broad or ambiguous to speak to multiple constituencies simultaneously, and (c) the concept needs to be sufficiently close to existing ways of understanding the policy issue – but also offer new perspectives looking forward.Drawing on social scientific studies and policy examples, I explore the ways in which these three factors played a role in the uptake of invasive species as a policy concept over the last 20 years. In particular, explorations will focus on the value dimensions inherent to invasive alien species as a policy concept, and on the discursive processes that allow diverse societal actors to come together in a coalition supporting control of invasive species. At the same time, there has also been significant opposition to the values mobilised through this policy concept. My talk will examine the factors and processes underpinning this critique, and highlight some of the possible pitfalls that come with the success of invasive alien species as a policy concept.

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DOI: 10.3897/aca.9.e205109

Authors: Martin Godefroid, Honorat Sabater Anticó, Jordi Mateu Pozuelo, Christopher Dietrich, Diana Gonzalez

Abstract: The spread of vector-borne plant diseases is increasingly influenced by environmental change, particularly shifts in climate conditions. This study focuses on the species distribution modeling of Scaphoideus titanus, the primary vector of Flavescence dorée, a major phytoplasma disease affecting grapevines across Europe. Using ecological niche modeling approaches and future climate scenario projections, we analyzed the current and potential future distribution of this vector species.Our results indicate a significant ongoing expansion of suitable habitats for S. titanus. In particular, recent emergence and establishment in Galicia (northwestern Spain) and northern France correspond with areas that have become increasingly favorable due to rising temperatures. These findings suggest that ongoing climate change is a key driver facilitating the spread of the vector beyond its historically known range.The expansion of S. titanus into new viticultural regions poses a growing threat to grapevine health and wine production. This study will help at designing an effective pest management strategy, which should be built on prevention, surveillance, eradication, and coordination and relies on institutional legitimacy, credibility, and public trust.

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DOI: 10.3897/aca.9.e205057

Authors: Laura Meyerson

Abstract: Ecological restoration and invasion science are disciplines that emerged from the recognition that human activities can have profound and often negative consequences for ecosystems and their species and that these systems and species may not recover or even continue to exist without further human intervention. Yet the two fields developed differently. Invasion science has largely focused on prevention, minimizing introductions and spread, managing pathways, prediction, social and economic drivers, and mitigating the impacts and risks of biological invasions. Restoration ecology, on the other hand, has focused more on repair, recovery, reassembly, resilience, and future ecologies. While perhaps initially perceived as distinct, these two ecological fields have become increasingly interdependent as biological invasions have risen globally across regions, ecosystem types, and taxonomic grous and disturbed and damaged ecosystems have been further compromised by biological invasions. Restoration efforts must account for non-native propagule pressure, altered disturbance regimes, introduced pathogens, soil and microbial legacies, reinvasion potential, and the possibility that restoration practices themselves may create invasion pathways, while management of biological invasions rarely succeeds through removal alone and often requires restoration of ecological processes, social legitimacy, governance support, and long-term stewardship. This talk explores the increasingly reciprocal relationship between invasion science and restoration ecology, arguing that invasion science can sharpen understanding of the ecological processes, thresholds, and legacies that shape recovery, while restoration ecology can expand invasion science toward resilience, repair, and the stewardship of future ecosystems.

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DOI: 10.3897/aca.9.e205050

Authors: Fengzhi He, Tao Wang, Xing Chen

Abstract: Megafauna species, including large mammals, reptiles, and fishes, have been intentionally introduced outside their native ranges due to their charisma and economic values. Given their wide introductions and documented ecological impacts, it is vital to synthesize the existing evidence to advance our understanding of their impact mechanism and magnitude, which could facilitate the development of effective management strategy. Here, we use freshwater megafauna as an example to demonstrate the multifaceted impacts of alien megafauna on the recipient ecosystems based on more than 2000 records systematically identified from published literature. Following the Environmental Impact Classification for Alien Taxa (EICAT and EICAT+) framework, we assessed the impacts of these large alien animals on native species. Moreover, we extracted data related to these species from the InvaPact Database, which applied large language models to identify and categorize alien species impacts, and used the metrics based on the Extended EICAT (EEICAT) framework to quantify their ecological impacts. Our results reveal the profound ecological impacts of over 70 alien megafauna species on the recipient ecosystems worldwide through various mechanisms, leading to changes in habitat structure, biotic interactions, and ecological processes. For example, about 50% of the identified alien freshwater megafauna species with sufficient data to assess their impact magnitude have caused population decline or even local extinction of at least one native species. Our results underscore the complex ecological impacts of alien megafauna and highlight the need for comprehensive assessment that consider multiple ecosystem components to advance our understanding of alien species impacts.

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DOI: 10.3897/aca.9.e204857

Authors: Clara Marino, Martin Philippe-Lesaffre, Jonathan Lenoir, Céline Bellard, Ana Benítez-López

Abstract: Island biodiversity is increasingly threatened by non-native species (NNS). Yet, no global map of island NNS richness has been produced to support global threat assessments. Using a hurdle random forest model informed by 11 biogeographic and anthropogenic predictors, we predicted NNS richness for 17,343 islands for the present day and the near future (2050). Biogeographic factors were the strongest predictors of NNS establishment, while the combined influence of biogeographic and anthropogenic variables best explained the accumulation of NNS across islands once established. We found NNS richness to be greater for larger, more elevated, and more remote islands, with high human population densities and low natural habitat proportions. Models predicted 54% of islands invaded in 2020, and an increase in NNS richness for 16% of these islands by 2050. These predictions help identifying islands prone to biological invasions, both today and in the future, and thus to derive conservation prioritizations.

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DOI: 10.3897/aca.9.e204903

Authors: Anna Gazda

Abstract: Citizen science (CS) has become an increasingly important tool in ecological research, particularly for monitoring non-native and invasive alien species (IAS). By enabling large-scale data collection across broad spatial and temporal gradients, CS provides new opportunities for understanding invasion dynamics while engaging the public in biodiversity monitoring Brown P. et al. 2023. This study evaluates the contribution of integrating CS-based invasive species monitoring with biodiversity monitoring to improve the detection and ecological understanding of IAS in Poland. Since 2019, our team has run two complementary CS projects during the same observation period using the iNaturalist platform: one focused on non-native species and the other on biodiversity in semi-natural ecosystems.We tested whether integrating these monitoring approaches improves IAS detection efficiency, spatial coverage, and ecological interpretation compared with invasive-species-focused monitoring alone.Multi-year datasets (2019–2026) were analysed using statistical approaches evaluating detection probability, spatial coverage, sampling effort, and species co-occurrence patterns. Since 2019, the projects have generated more than 24,000 observations of more than 2,000 species submitted by over 300 contributors across Poland. The integration of invasive species monitoring with broader biodiversity surveys increased spatial coverage compared with invasive-species-focused monitoring alone and improved detection of IAS in habitats where their occurrence had previously been underreported. By combining records of native and non-native species, the integrated monitoring framework provided additional ecological context, allowing identification of habitat associations and potential species interactions that would remain undetected in invasive-species-only datasets.The projects also supported long-term participant engagement, with many contributors progressing from casual observers to advanced identifiers and collaborators. Our findings demonstrate that a structured, hypothesis-driven CS framework can substantially improve early detection and mapping of invasive species while generating datasets suitable for ecological analyses.Importantly, the integration of CS-based biodiversity monitoring with invasive species surveys enhances the detection of biological invasions, improves ecological interpretation of invasion processes, and provides a scalable framework for biodiversity conservation, public engagement, and early-warning systems.

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DOI: 10.3897/aca.9.e204890

Authors: Jan Pergl, Jakub Hájek, Pavlína Hakrová, Handrij Härtel, Natálie Kolombová, Klára Kušková, Josef Kutlvašr, Irena Perglová, Daniela Steinbachová, Pavel Švec, Matěj Vetešník

Abstract: Long-term management of invasive alien plant species is essential for biodiversity conservation; however, its effectiveness varies among species, habitats, and management regimes, and is still insufficiently evaluated. In this contribution, we present a synthesis of long-term management outcomes for selected invasive plant species in the Czech Republic, integrating observational and experimental approaches across protected areas and managed landscapes.The study focuses on Lupinus polyphyllus and Impatiens glandulifera (Šumava National Park), Reynoutria spp. (Morávka Nature Reserve), Heracleum mantegazzianum (Karlovy Vary region), Pinus strobus (Bohemian Switzerland National Park), and Prunus serotina (managed forests) (Kušková et al. 2026). The evaluation is based on management trajectories spanning 10–25 years, enabling assessment of both short-term responses and long-term dynamics.Our results demonstrate that management effectiveness is strongly species-specific and closely linked to life-history traits. For example, a 17-year management programme on Reynoutria spp. shows that systematic herbicide application substantially reduces population extent and leads to fragmentation of large stands, yet does not result in eradication due to persistent regeneration from rhizomes and reinvasion processes. The high regenerative capacity of Reynoutria taxa, driven by vegetative reproduction and clonal growth, underpins their persistence in the landscape. Even intensive treatment over several years is insufficient for complete elimination, highlighting the necessity of sustained, multi-phase management strategies (Švec et al. 2024).Comparable patterns are observed across other species, where long-term suppression rather than eradication is the dominant outcome. The effectiveness of management of Lupinus polyphyllus is evaluated over a decade of intensive cutting and mulching, while the case of Pinus strobus is assessed over a 25-year management campaign combined with re-evaluation of previously invaded sites. Across all case studies, we identify key drivers of successful management, including treatment continuity, early intervention, and adaptation of methods to species-specific regeneration strategies.The study also has important policy implications, as several focal taxa (Heracleum mantegazzianum, Impatiens glandulifera, Reynoutria spp.) are included on the EU list of Invasive Alien Species of Union concern. Our synthesis highlights the need for robust, long-term datasets to evaluate the effectiveness of management measures underpinning such regulatory frameworks.By integrating multiple case studies across species and management contexts, this work provides evidence-based recommendations for improving long-term invasive species management in European protected areas.

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DOI: 10.3897/aca.9.e204881

Authors: Marco Morbidelli, Beatrice Melone, Sara Forni, Alessandro Franco, Giulia Bianchi, Riccardo Bonini, Nadia Cappai, Elena Tricarico

Abstract: Freshwater ecosystems (including riparian zones) are particularly vulnerable to invasive alien species (IAS) due to their high biodiversity (Pusey and Arthington 2003; Albert et al. 2021) and the numerous ecosystem services they provide to humans. Among freshwater taxa, decapods face the highest level of threat, as 30% of their species are classified as endangered (Sayer et al. 2025). This study assesses how the populations of the native white-clawed crayfish (Austropotamobius pallipes complex; hereafter A. pallipes) in the Foreste Casentinesi, Monte Falterona, and Campigna National Park (FCNP) (Central Italy) are affected by the invasive Northern raccoon (Procyon lotor), an omnivorous mammal from North and Central America first recorded in the protected area in 2013 (Cappai et al. 2016). In fact, crustaceans can represent the second most important food item and account for up to 60% of the total diet based on frequency of occurrence in raccoon scats (Boncompagni et al. 2021).Crayfish populations were surveyed between 2021 and 2023 at 51 stream sites (14 in Tuscany and 37 in Emilia-Romagna), each sampled once along a 100-m nocturnal transect (Morbidelli et al. 2026). Most sites (48 out of 51) had previously been surveyed between 2012 and 2016 using the same sampling protocol, allowing comparison between the early phase of the raccoon invasion and the 2021–2023 surveys. Raccoon occurrence data were obtained from camera trapping, live trapping, field signs (e.g. feeding remains) and validated reports. Crayfish sites were classified as raccoon-present (R1) when at least one raccoon record occurred within 500 m of the site during the same year as crayfish sampling; all remaining sites were classified as raccoon-absent (R0). Differences in crayfish abundance were then assessed using Catch Per Unit Effort (CPUE) and the temporal change in CPUE (ΔCPUE) between monitoring periods.No significant differences between R0 and R1 populations were detected for the 2012–2016 period (p > 0.05). In contrast, during 2021–2023 crayfish abundance was significantly lower in populations where raccoons were recorded (median CPUE: R0 = 56, R1 = 3; p < 0.001). The temporal variation in abundance also differed significantly between groups (median ΔCPUE: R0 = -0.47, R1 = -0.95; p < 0.001). Generalized linear and linear models confirmed the negative association between raccoon presence and both CPUE and ΔCPUE. Furthermore, crayfish size-class distributions differed significantly between R0 and R1 populations (χ² = 10.19, df = 4, p = 0.037). Environmental variables measured during sampling (stream width, water depth and water temperature) were comparable among the surveyed sites.These findings suggest that raccoon presence may represents a key driver of the decline of A. pallipes populations in the study area, providing quantitative evidence of the impact of an invasive mammal predator on a freshwater species already threatened by multiple human-driven factors and protected under the EU Habitats Directive. Control activities are currently underway by the Park authority, in order to contain the raccoon population in FCNP, and crayfish monitoring is still ongoing to assess potential recovery. Overall, these results highlight the need for further research on the ecological impacts of IAS to improve management strategies and strengthen conservation efforts for native fauna in protected areas.

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DOI: 10.3897/aca.9.e204693

Authors: Muriel Thirion

Abstract: Invasive alien species do not recognise administrative borders - and neither should their management.For six years, the LIFE RIPARIAS project has brought together Belgium's three regions, scientists, public authorities, and field managers to tackle one of the most pressing threats to biodiversity: biological invasions. Supported by a €7 million budget, the project focused on invasive plants and crayfish species affecting rivers, wetlands, and ponds, while developing innovative approaches to guide management decisions across jurisdictions.From pilot actions in the Dyle, Senne, and Marcq river basins to the development of evidence-based decision-support tools, LIFE RIPARIAS has sought to transform fragmented responses into a coordinated national strategy. The project combined scientific expertise, field experience, stakeholder engagement, and public awareness to improve surveillance, prioritisation, and management of both widespread and emerging invasive alien species.As LIFE RIPARIAS comes to an end in 2026, this presentation will look back on six years of collaboration, innovation, successes, and challenges. We will present the project's major achievements, focus on practical lessons learned during management actions, and reflect on how science-driven management maximises the effectiveness of investments in nature conservation.Beyond its Belgian context, LIFE RIPARIAS offers valuable insights for any region seeking to address biological invasions through cooperation, adaptive management, and evidence-based decision-making.

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DOI: 10.3897/aca.9.e204646

Authors: Henrique Couto, Rui Rebelo, José Grosso-Silva, Pedro Cardoso, César Capinha

Abstract: The availability of invasion-related data has increased substantially over the past decade, driven by technological advances and growing concern about the impacts of biological invasions. However, the integration of these data into consistent and interoperable formats suitable for geographically and taxonomically comprehensive analyses remains a major challenge. This difficulty stems from the high fragmentation of data sources, inconsistencies in reporting practices and terminology, and differences in geographic and taxonomic standardization (Castro et al. 2023, Seebens et al. 2025). These challenges are particularly pronounced in highly diverse groups with unresolved or rapidly evolving taxonomy, where species identification can be complex.Efforts to integrate data on the global distribution and trends of biological invasions in Lepidoptera (moths and butterflies) exemplify these issues. Lepidoptera is one of the most diverse insect orders, yet previous data integration efforts have been fragmented, often focusing on specific regions, taxonomic subsets, or species of particular concern (e.g., agricultural pests), and relying on inconsistent terminology and taxonomic frameworks.Here, we present a comprehensive global database of the regional distribution of non-native, established Lepidoptera species. We compiled information from 1,167 sources, including peer-reviewed literature, regional databases (e.g., USDA Invasive Species Database; APASD – Asian Pacific Alien Species Database), global repositories (e.g., CABI Compendium; GRIIS – Global Register of Introduced and Invasive Species), and technical reports. For each record, we extracted species identity, geographic location, native range, introduction pathway (intentional, natural dispersal, or accidental/unknown), year of first observation, and establishment status, resulting in 18,289 unique records.To ensure adherence to FAIR principles (Findable, Accessible, Interoperable, and Reusable), we harmonized geographic data to internationally recognized countries and insular regions, and standardized taxonomy through cross-validation using the GBIF Backbone Taxonomy and the Global Names Verifier. The database will be made publicly available through an R package and a SQLite database to facilitate reuse and integration.We identified 986 Lepidoptera species with non-native established populations, representing approximately 0.64% of the total richness of the order. Records date back to the 16th century, with a marked increase throughout the 20th century, particularly after 1960. Most species are restricted to one or two regions, although 67 species are established in ten or more regions out of 258 regions. Asia and Europe emerge as the primary source regions, while most documented establishments occur in temperate, economically developed regions, especially in Europe and North America.These results highlight both the global extent of Lepidoptera invasions and the critical importance of standardized, large-scale data integration for advancing our understanding of invasion dynamics in the context of rapid environmental change and expanding data availability.

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DOI: 10.3897/aca.9.e204676

Authors: Jonathan Tibo, Hanne Danneels, Sabrina Neyrinck, Jeroen Van Wichelen, Hans Jacquemyn, Rein Brys

Abstract: Globalization is accelerating species translocations beyond natural dispersal boundaries, increasing the introduction of non-native species into new ecosystems. Although most introduced species fail to establish, those that do have the potential to become invasive and negatively affect native biodiversity, especially when closely related to native taxa. This process is currently unfolding along the Belgian–Dutch border, where a large metapopulation of the endangered European weather loach (Misgurnus fossilis) is increasingly threatened by the expansion of the non-native Asian weather loach (Misgurnus bipartitus). Misgurnus bipartitus was first detected in the Netherlands in 2012 and subsequently expanded into Flanders (Belgium), where it was first recorded in 2019. Shortly after this initial Belgian record, an environmental DNA (eDNA) survey was conducted across 32 sites to provide the first regional-scale assessment of the native and non-native weather loaches, using a droplet digital PCR (ddPCR) protocol for species-specific detection and quantification. In 2025, we conducted an expanded follow-up survey, revisiting the original sites and extending the sampling to over 100 locations to: update the current distribution of both species, assess spatio-temporal changes in their distribution and relative abundance across the two surveys, and identify zones of sympatry to prioritize for management. Our results reveal the presence of novel sympatric populations and several locations where spatio-temporal shifts have occurred since 2019, captured through changes in eDNA concentrations. Overall, these findings illustrate the value of repeated ddPCR eDNA monitoring for tracking native and non-native species through space and time.

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DOI: 10.3897/aca.9.e204575

Authors: Zygmunt Dajdok, Zbigniew Celka, Marcin Dyderski, Marcin Nobis, Artur Pliszko, Katarzyna Bzdęga, Julian Chmiel, Władysław Danielewicz, Czesław Hołdyński, Alina Urbisz, Blanka Wiatrowska, Adam Zając, Barbara Tokarska-Guzik

Abstract: The comprehensive list of non-native plants in Poland was published 14 years ago (Tokarska-Guzik et al. 2012). Due to rapid changes in non-native flora this list has now been revised and updated. In the current study particular attention has been paid to the occurrence of invasive alien plant species (IAPS) within Natura 2000 habitats. We focused on the number of IAPS identified within individual habitat types and the impact category of these species according to the Environmental Impact Classification for Alien Taxa - EICAT (IUCN Species Survival Commission (SSC) 2020). The threat category of individual habitats was adopted from the Red List of Natura 2000 Habitats of Poland (Korzeniak et al. 2025), where habitats were assessed according to the IUCN criteria (IUCN Standards and Petitions Committee 2024).We identified 83 taxa invasive at both – the national and regional levels, occurring across 53 Natura 2000 habitat types, including 21 in the EN (endangered) category, 12 in VU (vulnerable), and 10 in CR (critically endangered). The highest number of IAPS was recorded in Hydrophilous tall herb fringe communities – 6430 (DD - data deficient) and Lowland hay meadows – 6510 (VU) – with 30 and 28 species, respectively. The other habitats with 10 or more IAPS recorded within them include species-rich meadows, fringe communities and riparian forests. Some of them belong to the group of priority habitat, e.g.: Xeric sand calcareous grasslands – 6120* (DD), Rupicolous calcareous or basophilic grasslands – 6210* (EN), and Alluvial forests – 91E0* (VU).Considering the species impact categories according to the EICAT classification assigned to the analysed IAPS, two groups of species are predominant – the MI (minor) and MO (moderate) categories. The next largest groups consist of species in the MR (major) and the MA (massive) category. The smallest group of IAPS consists of species in the category ML (minimal concern).An analysis of the proportion of IAPS with varying impacts within habitat groups of the same threat category (using a generalized linear model for discrete variables (negative binomial)), showed statistically significant differences between habitats of the CR and DD categories, whereas the remaining categories did not differ from one another. Considering the IAPS with the highest impact categories (massive - MA and major - MR), a similar trend was observed – their lowest number was recorded in the habitats of CR category and the highest – in habitats classified as EN and DD.Our results indicate that in case of the most threatened Natura 2000 habitats in the CR category (primarily salt marshes and peatlands) IAPS are not very numerous. Main factors that threaten those habitats are deteriorating hydrological conditions, changes in nutrient composition, acidification or salinization stress, or a combination of these factors. In contrast, the highest number of IAPS has been recorded in habitats classified as EN or Data Deficient (DD). This suggests that when prioritizing measures to conserve species diversity in natural habitats, special attention should be focused not only on habitats with the highest threat categories but also on those with lower status, given the pressure exerted by large number of IAPS.

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DOI: 10.3897/aca.9.e204095

Authors: Thomas Campagnaro, Giulia Foresta, Flora Simonelli, Nicola Menon, Samuele Pescarolo, Davide Bergomi, Michele Macellari, Tommaso Sitzia, Lorenzo Picco

Abstract: Ailanthus altissima is a widespread invasive species in Europe and poses significant challenges for ecosystem management and conservation. However, its patterns of spread and ecological impacts are still not fully understood. The objective of this study was to elucidate the ecological patterns and processes associated with Ailanthus altissima invasion in a riparian landscape and to provide a basis for evidence-based management strategies. To address this objective, we analysed invasion foci within the Brenta riverscape (northeastern Italy). We identified invasion foci within a Natura 2000 site located along the middle course of the river. For each stem (>4000) within 18 invaded sites, we recorded its location and size (i.e., height and diameter). We then examined the spatial arrangement of A. altissima individuals and their relationship with landscape factors (i.e., distance from the main channel of the Brenta River and main land cover). Clustered spatial distribution was observed within invasion foci. Furthermore, invasion dynamics appear to be associated with localised management activities (e.g., paths, mowing). Our results provide ecological insights that may support more effective prevention and control strategies. Furthermore, analysing these dynamics improves our understanding of the structural development of Ailanthus stands and helps predict the evolution of invasion foci in riparian landscapes.

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DOI: 10.3897/aca.9.e204137

Authors: Karim Abufarhue, Lucila Moreno Salas, Reinaldo Rivera, Anibal Pauchard

Abstract: Biological invasions in urban environments are shaped by both environmental suitability and human-driven processes; yet most studies address these dimensions independently. Here we present an integrative framework combining ecological niche modelling and sociodemographic analysis to understand the invasion dynamics of the red-eared slider (Trachemys scripta) in cities along a latitudinal gradient encompassing the Chilean Matorral and Valdivian Temperate Forests ecoregions (33°–40°S).In a first component, we assessed habitat suitability for T. scripta across Chile using species distribution models calibrated on native range occurrence data from global databases (GBIF), field surveys, and unpublished local citizen science records, and evaluated the niche conservatism hypothesis by comparing environmental conditions occupied in the native and non-native ranges using multivariate analyses in environmental space. Results indicate moderate niche overlap (D = 0.364), with similarity significantly greater than expected by chance (Pd = 0.012) and high conservation of the native niche (stability = 0.788), while a fraction of the native niche remains unfilled in Chile (unfilled = 0.199), indicating the species is in an active expansion stage with additional colonization potential in the Chilean Mediterranean zone.In a second component, we modelled the occurrence of T. scripta across 49 urban water bodies in cities of central Chile using a Generalized Linear Mixed Model with a model averaging approach (MuMIn::dredge, delta AICc ≤ 4). We incorporated sociodemographic variables extracted at census block resolution (Censo 2024, INE Chile) within 500 m buffers around each water body, urban infrastructure predictors, a composite physical accessibility index, an index of active conservation management at the site level (environmental signage and NGO presence), and landscape composition metrics.Preliminary results suggest that physical accessibility to water bodies, the socioeconomic context of the surrounding area, and the level of active site management emerge as the main mediators of invasion success in urban environments. Among the sociodemographic variables evaluated, average educational attainment — interpreted as a proxy for consumer capacity and exotic pet ownership — was the only significant predictor of T. scripta presence (OR = 2.87; 95% CI = 1.46–6.41), while indicators of structural poverty, population density, and age structure showed no association. This pattern suggests that the invasion is driven by middle-to-upper socioeconomic strata with capacity to access the exotic pet trade, rather than by demographic pressure or material deprivation.Collectively, these findings position the urban invasion of T. scripta as a socioecological process that cannot be fully understood through ecological lenses alone. This integrative approach offers a transferable framework for managing reptile invasions in rapidly urbanizing cities of South America.

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DOI: 10.3897/aca.9.e204162

Authors: Marta López-Darias, Jorge Fernando Saavedra Bolaños, José Miguel Sánchez Rivero, Andrea Castro Martín, Julien Piquet, Borja Maestresalas, Ramón Gallo-Barneto

Abstract: Invasive snakes pose a growing threat to biodiversity, yet effective and selective trapping tools remain scarce for their adequate control. This study presents the design and evaluation of novel mechanisms aimed at enhancing trap selectivity for the control of the invasive California kingsnake (Lampropeltis californiae). We tested custom-designed entrance mechanisms—including funnels, turnstiles, U-shaped profiles, and longitudinal systems—under controlled and field conditions experiments and explored their success in minimizing non-target captures of endemic reptiles (Gallotia stehlini and Chalcides sexlineatus). Controlled experiments revealed that all selective mechanisms successfully guided L. californiae, while excluding non-target species. Field trials confirmed the high selectivity of the mechanisms, reducing non-target captures by over 98% compared to control traps. Although some mechanisms showed reduced effectiveness for smaller snakes, the integration of a 21 × 21 mm entrance profile and selective mechanism designs significantly improved operational efficiency. These findings offer scalable solutions for invasive snake management elsewhere and highlight the importance of trap refinement in optimizing control programs globally.

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DOI: 10.3897/aca.9.e204115

Authors: Fanny Kratz, Lore Esselens, Ann Vanderheyden, Samuel Vanden Abeele, Sam Vanbergen, Pablo Deschepper, Marc De Meyer, Massimiliano Virgilio, Jochem Bonte, Wannes Dermauw

Abstract: Bactrocera dorsalis is one of the most important pests of commercial fruit crops worldwide and is regulated as a priority quarantine pest in the European Union. Between 2023 and 2025, adult males were detected for the first time in Belgium during national surveillance in public markets and community gardens. Together with earlier interceptions of larvae in imported fruit, especially mangoes, these findings raised key questions about the origin of the specimens and whether the Belgian detections reflected a single introduction event or repeated incursions through different pathways. Trapped adult males were identified morphologically, while intercepted larvae were identified using molecular assays supported by morphology. All specimens were then analysed using whole-genome sequencing. Geographic assignment was investigated by comparing nuclear genomic variation with broad reference datasets, while mitochondrial genomes were analysed in parallel to assess whether mitochondrial patterns were consistent with nuclear-based inference. Both nuclear SNP variation and mitochondrial phylogeny supported differentiation between African and Asian reference populations. Within this framework, most trapped adults were assigned to Asian populations, whereas nearly all intercepted larvae grouped with African reference material. Formal origin assignment was achieved using a reduced diagnostic nuclear SNP panel and a standardized discriminant analysis of principal components (DAPC) based on COI barcodes. These methods produced largely consistent results, while also highlighting occasional cases of mitonuclear discordance. Our analyses indicate that the adult males detected in Belgium do not represent a single introduction, but multiple independent incursions. The contrast between the inferred origin of trapped adults and that of larvae intercepted in fruit suggests that distinct introduction pathways may be involved, including intra-European trade and unauthorized fruit imports. The reduced nuclear SNP panel and the COI-based assignment framework provide scalable tools for plant protection agencies and diagnostic laboratories, supporting faster origin tracing, pathway analysis, and more targeted phytosanitary surveillance and response.

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DOI: 10.3897/aca.9.e204113

Authors: Neil Angelo Abreo, Ismael Soto, Phillip Haubrock

Abstract: Biological invasions is a component and consequence of anthropogenically-driven global environmental change that is threatening ecosystems and the benefits they provide. Decades of research have established conceptual frameworks to understand the complex dynamics of invasions and its impacts. However, taxonomic biases in formulating these frameworks limit our perspective that often results in misinformed decisions that can cause unwanted management results. Here, we discuss the characteristics of Lepidodactylus lugubris that are relevant to existing invasion science frameworks and outline how using this species as a model can advance the field. We underscore four areas where L. lugubris can improve invasion science. The unique biological characteristics of the species can helptest the generality of invasion hypotheses largely developed from plants and invertebrates; andthe presence of multiple clonal lineages tests genotype-specific invasion success, niche use and impacts. The strong association of this species with trade and anthropogenic structures allowlinking introduction pathways to ecological outcomes; and lastly, its interaction-driven effectsexemplify the context-dependence of biological invasion impacts.Treating L. lugubris as a model system exposes mechanistic assumptions that currently underpin applied invasion frameworks—particularly regarding propagule pressure, pathway attribution, and impact scaling—and highlights how incorporating life-history traits, pathway structure, and context dependence can improve invasion risk assessment, surveillance design, and prioritisation across taxa associated with human infrastructure.

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DOI: 10.3897/aca.9.e204106

Authors: Fanny Kratz, Lore Esselens, Ann Vanderheyden, Samuel Vanden Abeele, Hafsi Abir, Hélène Delatte, Pia Addison, Domingos Cugala, Maulid Mwatawala, Ghania Barech, Mourad Khaldi, Nathalie Smitz, Marc De Meyer, Jochem Bonte, Wannes Dermauw, Massimiliano Virgilio

Abstract: Dacus frontalis is an economically important fruit fly widely distributed across Africa and already intercepted in the European Union, making reliable diagnostics essential for trade and phytosanitary surveillance. Recent coordinated sampling with African partner institutions revealed unusually high mitochondrial divergence in the cytochrome c oxidase subunit I (COI) barcode region, with approximately 4% divergence between North African and sub-Saharan populations. This level of intraspecific variation complicates routine identification and highlights the need for a geographically broader molecular reference framework, as well as complementary genomic tools able to resolve lineage structure and support future origin tracing. To improve diagnostic robustness, we are expanding continental COI coverage by generating new Sanger barcodes and by recovering mitochondrial barcode sequences from short-read genomic datasets. In parallel, we are developing an ortholog-based genomic workflow that combines OMA standalone for ortholog detection with Read2Tree for phylogenomic reconstruction. This framework is intended to move beyond single-locus inference and provide genome-wide resolution of differentiation patterns within D. frontalis. Current analyses based on COI consistently recover two well-differentiated mitochondrial lineages, broadly corresponding to northern and sub-Saharan sampling regions. Increasing barcode coverage is improving the representation of African populations and refining our interpretation of this divergence. The ortholog-based component is still under development, but it is expected to test whether the same structure is supported across the nuclear genome and to identify markers useful for future origin-tracing applications. Building an integrated molecular framework combining expanded COI coverage with an emerging ortholog-based genomic approach will strengthen diagnostic capacity for D. frontalis. By enabling more robust identification and providing a foundation for future origin tracing, this work supports early detection, surveillance, and phytosanitary preparedness in Africa and in regions at risk of introduction, including the European Union, where D. frontalis has already been detected in France and a single intercepted specimen was recorded in Belgium.

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DOI: 10.3897/aca.9.e204108

Authors: Corin Pratt, Djamila Djeddour, Elizabeth Pendlington, Anna Tilling, Sonal Varia, Suzy Wood

Abstract: Invasive aquatic weeds pose major threats to biodiversity, ecosystem function, economic activity and leisure use of freshwater habitats. Dense infestations alter hydrology, displace native species, impede navigation, and impose substantial management costs on water authorities and land managers. Effective long‑term control is a high priority. Mechanical and manual control approaches are widely used but are typically short term, costly, and must be repeated regularly to maintain suppression. Restrictions on herbicide use in and around water bodies in the EU and Great Britain due to concerns over non‑target impacts and water quality limit the potential role of this management tool. These constraints limit the efficacy and economic viability of conventional management techniques for long term control and intensify the need for alternative solutions.Classical biological control (CBC) offers a highly selective, environmentally benign and self‑sustaining approach to invasive weed management. Following rigorous host‑specificity testing, carefully selected natural enemies from a weed’s native range are released to provide population regulation in perpetuity, often at landscape scales and with minimal ongoing intervention. CBC targeting aquatic weeds has delivered impressive outcomes against numerous targets on multiple continents, with long‑term ecological and economic benefits which are described.In Great Britain, and more recently in continental Europe, substantial progress has been made in developing CBC programmes for priority aquatic weeds. Current field release programmes target Azolla filiculoides, Crassula helmsii and Hydrocotyle ranunculoides in GB and northern Europe. Candidate biocontrol agents for Myriophyllum aquaticum and Elodea spp., are undergoing host‑specificity testing in GB quarantine facilities, while Ludwigia spp. have been subject to fundamental CBC research. Additional species prioritised as future targets are also detailed. These initiatives highlight the growing role of CBC as a cornerstone of sustainable invasive aquatic weed management in Europe.

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DOI: 10.3897/aca.9.e204099

Authors: Simeon Wilton, Louise Barwell, Daniel Chapman, Helen Roy

Abstract: Harmonia axyridis, the harlequin ladybird, is an invasive non-native species now found in many countries around the world. First recorded in Britain in 2004, it spread rapidly across the country and has become the most abundant ladybird species in ladybird assemblages, particularly in urban habitats. There is evidence that H. axyridis has led to declines in some native ladybird species through competition and predation (Roy et al. 2012). However, the impacts of these shifts in ladybird assemblages for ecosystem function and resilience remain poorly understood. H. axyridis is an intraguild predator, that is, it feeds both on aphids and other insects that also feed on aphids, which includes both hoverfly species and other species of ladybird. Hoverflies are crucial pollinators, and some species of ladybird and hoverfly are important for controlling pest insects. Here I explore the impacts of H. axyridis on trends before and after its arrival on both hoverfly and ladybird species in Great Britain. Using spatio-temporal occupancy-detection models, I assess whether the presence of H. axyridis is correlated with changes in the distribution of 186 hoverfly and 30 ladybird species in Britain. I explore whether diet overlap between H. axyridis and native hoverfly species contributes to its impact, distinguishing species whose larvae consume aphids from those that do not, and whether habitat type similarly affects trends in hoverfly and ladybird occupancy. Shifts in the community composition of aphidophagous insects may lead to cascading effects throughout the wider network of interacting species with consequences on ecosystem function and resilience and ultimately adverse impacts on nature and people.

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DOI: 10.3897/aca.9.e204075

Authors: Ava Waine, Peter Robertson, Zarah Pattison

Abstract: Raw water transfer (RWT) schemes (engineered networks of pipelines, tunnels, and supply canals that move large volumes of freshwater between separate waterbodies) represent one of the most understudied invasion pathways in freshwater ecology. This is despite global prevalence and rapid expansion of RWTs driven by population growth, urbanisation, and climate-driven water scarcity. Environmental regulators in Britain have recently introduced requirements for stakeholders to risk assess and manage the RWT invasion pathway, yet critical assessment of the available literature reveals that few RWT studies have been conducted worldwide and pathway understanding remains limited.Field investigations of three structurally distinct RWTs in northeast England revealed that RWTs disperse a taxonomically diverse range of aquatic taxa, under propagule pressure levels potentially exceeding those of any other freshwater pathway of unintentional spread. Sampling yielded viable specimens of 16 distinct species across all three RWT schemes, including fish, molluscs, and arthropods, with a further seven species sampled in non-viable form. Introduction risk was associated with the type of physical infrastructure barrier, particularly pumps, rather than transfer distance.Reconstruction of historic invasive non-native species (INNS) dispersal using a network-distance analysis method confirmed RWTs as key drivers of INNS spread, particularly of small-bodied invertebrates and aquatic and riparian plants. Results also showed that RWT infrastructure has substantially restructured natural hydrological connectivity at a regional scale, consequently facilitating INNS dispersal.Given the significant and growing threat RWTs pose to global freshwater biodiversity, this research calls for integration of RWT pathway management within broader INNS surveillance frameworks and accurate reclassification of RWTs within international pathway classification systems.

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DOI: 10.3897/aca.9.e203973

Authors: Corin Pratt, Iain Paterson, Karla Jaschke, Daisuke Kurose, Marion Seier

Abstract: Carpobrotus edulis (Aizoaceae) is a succulent perennial native to South Africa, but invasive in southern Europe, Great Britain (GB) and Ireland, USA, Australia, and New Zealand. It spreads rapidly via creeping stems, forming dense mats. Favouring sandy soils, it thrives in coastal habitats, particularly dunes and cliffs. In GB, it has established itself along the south-western and southern coasts. Its vigorous growth outcompetes native flora, threatening biodiversity and altering the ecosystem structure and function of fragile coastal areas. Management is necessary to protect vulnerable sites but can be challenging in unstable or inaccessible locations. Following a Natural England stakeholder workshop in 2022, C. edulis was prioritised for biocontrol and a feasibility study was undertaken by CABI. This was followed by a survey to identify natural enemies of the plant in GB, including an introduced South African scale insect. The paucity of damaging and specific natural enemies in GB prompted a subsequent survey in 2023 to the native range of the plant, organised in collaboration with the Centre for Biological Control, Rhodes University, South Africa. An array of natural enemies were recorded, with scale insects and a pathogen brought to the UK for culturing and further evaluation. In 2025 and 2026 additional targeted surveys were conducted to collect two species of stem-mining beetles. Details will be provided on the status of the biocontrol study, and the natural enemies prioritised.

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DOI: 10.3897/aca.9.e203963

Authors: Liliana Duarte, Joana Gaspar de Freitas, Nuno Guiomar, Hélia Marchante, Carlos Pinto Gomes, Elizabete Marchante

Abstract: From the late 18th century, several countries implemented dune stabilization and afforestation programs using fences and vegetation to control sand drift. In Portugal, afforestation was assured by the Forestry Services since 1886, who mainly used Pinus pinaster complemented with native and alien species. The Australian Acacia longifolia was one of the species sown and grown in the dunes and nurseries, later revealing invasive behavior. This study reports the historical pathway of A. longifolia introduction, establishment and spread in 23 forested areas along a 180 km coastal stretch, under the Portuguese forest regime. Foresters’ reports, management plans and distribution maps from 1852 onwards were reviewed. The evidence gathered supports that A. longifolia was likely introduced after 1897 at São Jacinto and Gafanha dunes. Following several years of experimentation and trial, A. longifolia was recommended for sand dune afforestation in 1905. Its first use was reported in Mira by 1919 for the stabilization of drainage ditches, and by 1948 nearly 12 000 ha of central coastal dunes had been sown and/or planted with this species. The current distribution of A. longifolia reflects both its use continuing until at least 1955, and the major role of disturbances as triggers for its expansion. A major windstorm in 1941 may have facilitated its spread in affected areas where it was already present, and its introduction to other forested areas. Wildfires in the 1990’s triggered its rapid expansion, promoting a landscape shift towards an A. longifolia-dominated shrubland. The earliest record of invasive behavior is from 1983 and the species was legally listed as such in 1999 (DL 595/99). Eighty-five years after it was introduced in coastal dunes, A. longifolia management has become much more difficult due to a 1000-fold increase in the number of seeds m-2 in the seedbank. This highlights its invasive potential in Portugal. The factors influencing the species’ current distribution and status are discussed.

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DOI: 10.3897/aca.9.e203961

Authors: Liliana Duarte, Hélia Marchante, Francisco López-Núñez, Fiona Impson, Francisco Moreira, Elizabete Marchante

Abstract: Acacia longifolia (Andrews) Willd., an Australian tree introduced to Portugal for dune stabilization in late 19th century, has become a widespread invasive plant that severely impacts biodiversity and ecosystem services. Its success is mainly attributed to its ability to produce and accumulate persistent seed banks. Conventional physical and chemical management is often prohibitively expensive and provides only short-term suppression. To address this, the Australian bud-galling wasp Trichilogaster acaciaelongifoliae (Froggatt) (Hymenoptera: Pteromalidae) was introduced in 2015 as a biological control agent to reduce the plant's massive reproductive output. This study evaluates the long-term impact of T. acaciaelongifoliae on A. longifolia seed dynamics at several coastal dune sites in central Portugal. Annual seed rain was quantified over five to six years (2019–2024) using seed intercept traps, while seed bank replenishment since introduction was assessed through soil and litter sampling. Cover by T. acaciaelongifoliae galls increased significantly over time, reaching a "tipping point" five years after release. This resulted in a reduction in annual seed rain that reached up to 98.1% in some of the areas. The increase in galls induced physiological stress on the host plants, causing a significant rise in phyllode abscission, and eventually plant mortality. While the overall seed bank still increased gradually between 2015 and 2024, replenishment began to stabilize in areas where the biocontrol agent had been established for more than six years. Mechanical control and wildfire events were found to enhance seed bank depletion, especially when integrated with the sustained presence of the biocontrol agent.The results demonstrate that T. acaciaelongifoliae effectively suppresses the reproductive potential of A. longifolia and slows the accumulation of its persistent seed bank. These findings highlight the importance of adopting an integrated management strategy – combining biocontrol with conventional methods – to ensure the sustainable restoration of invaded coastal habitats in Portugal.

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DOI: 10.3897/aca.9.e203825

Authors: Haldre Rogers

Abstract: The invasion of the brown treesnake (Boiga irregularis) on Guam led to the loss of nearly all native forest birds and decline in several native lizards, triggering ecosystem-wide changes that extend far beyond direct predation. Using comparative data from across the Mariana Islands, I will show how the disappearance of pollinators, frugivores, and vertebrate insectivores alters pollination interactions, disrupts seed dispersal, and reshapes forest gap dynamics and successional trajectories. The collapse of vertebrate insectivory has also contributed to dramatic increases in spider abundance and major shifts in arthropod communities. Together, these cascading effects constrain plant recruitment, limit the regeneration of historically common native species, and modify the spatial patterning and pace of forest recovery. I will also highlight how mapping the island’s ecological interaction networks can identify leverage points for more effective snake control and for enhancing ecological function, including strategies to expand the influence of the sole remaining native avian seed disperser. These insights provide a framework for integrating ecological understanding with management approaches for invasive snakes and other top predators.

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DOI: 10.3897/aca.9.e203716

Authors: Sven Jelaska, Damjana Levačić, Mario Paradžik

Abstract: Gazania rigens (L.) Gaertn., commonly known as gazania or treasure flower, is a member of the Asteraceae family native to southern Africa. Introduced to Europe in the 18th century as an ornamental plant due to its vibrant yellow inflorescences, the species behaves as a perennial in warmer climates and an annual in colder regions. Its perennial nature facilitates naturalization, occasionally leading to invasiveness in regions such as parts of Europe and Australia. Using available GBIF data (as of April 2026), we analyzed the distribution of G. rigens in Europe to assess its potential for further expansion. Of the roughly 3,000 recorded gazania localities, only 166 (5%) predate the year 2000. An additional 304 localities were reported over the following decade, primarily concentrated in European coastal areas. Post-2010, records surged exponentially, with a substantial number emerging in inland parts of the continent.To determine the environmental preferences of the species, we calculated descriptive statistics using BioClim climate data (worldclim.org) and SoilGrids data (soilgrids.org) for soil chemical properties (nitrogen, organic carbon, and pH) at a depth of 0–5 cm. To match the spatial resolution of SoilGrids, we filtered the data to retain only localities with a reported spatial accuracy of ≤ 250 m, yielding a subset of 1,594 localities (53%). Spatial overlap comparison between the full dataset and the filtered 250-m dataset—projected onto a 10-km ETRS grid—revealed that 67% of the grid cells remained identical. Furthermore, these cells were evenly distributed across the species' range, ensuring the representativeness of the 250-m subset.Our findings indicate that G. rigens prefers slightly acidic to slightly alkaline soils; 50% of the localities (interquartile range) exhibited pH values between 6.2 and 7.3, while 80% (10th to 90th percentiles) fell between 5.9 and 7.6. Nitrogen concentrations ranged from 2.6 g/kg (10th percentile) to 7.2 g/kg (90th percentile). Although the minimum annual precipitation (BIO12) was 130 mm, the 10th-to-90th percentile range spanned 487–984 mm, characteristic of a continental climate. However, precipitation during the driest month (BIO14) was 39 mm at the 75th percentile and 48 mm at the 90th percentile, signaling a strong tolerance to drought. Conversely, the species is sensitive to cold conditions. The minimum temperature of the coldest month (BIO6) was 0.7 °C at the 10th percentile, whereas the maximum temperature of the warmest month (BIO5) ranged from 22.3 °C (10th percentile) to 30.6 °C (90th percentile).Currently, the majority of European gazania records are concentrated in France, Portugal, Spain, and the United Kingdom, with sporadic or localized clusters elsewhere (e.g., Sardinia and Sicily in Italy, Corfu and Crete in Greece). Habitat suitability modeling via MaxEnt indicates a high potential for eastward expansion. Favorable climatic conditions could facilitate its spread across Italy, the coastal regions of Croatia, Albania, and Greece, and along the southern coast of the Black Sea. Additionally, suitable soil characteristics support potential inland establishment stretching from Italy to Turkey. Given the documented negative impacts of G. rigens on native flora and habitats in regions like Spain, targeted monitoring and potential commercial trade bans are strongly recommended.

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DOI: 10.3897/aca.9.e203683

Authors: Nigel Taylor, David Aldridge, Alec Christie, Katie Costello, Sam Reynolds, Kevin Smith, William Sutherland, Rosie Trevelyan, Tamryn Venter, Thomas Worthington, Ana Nunes

Abstract: Coordinated, effective and efficient management of invasive alien species (IAS) relies on access to standardised information on past and ongoing control efforts. However, existing data are typically fragmented, difficult to locate, inconsistently formatted, or remain unpublished – particularly in cases where management was less successful. This limits the potential for past efforts to inform the design of future management strategies and to identify knowledge gaps that could be filled by applied research.To help address these challenges, for example by increasing reporting rates and improving the quality of recorded data, we co-developed a unified data framework capable of capturing salient information on IAS removal projects. The framework is applicable to all types of IAS, management objectives (e.g. from containment to eradication), removal techniques and monitored outcomes, for any location and spatiotemporal scale, and for any degree of success.We produced a first draft of the framework by reviewing existing standards, databases, and reporting systems. This was refined through a series of online and in-person workshops involving >70 participants with expertise in IAS management from >30 countries. Finally, we tested the framework by extracting data for case studies from a variety of sources.The framework is split into sections capturing: project details, target IAS, goals, actions taken, economic costs and benefits, outcomes, reflections on implementation, and linked resources. The framework is deliberately comprehensive, containing >90 questions. However, the burden of data entry is reduced by conditional logic (some questions only appear if relevant based on previous responses), acknowledging that some data (e.g. detailed quantitative outcomes) can be captured by other linked frameworks, and highlighting a small subset of essential questions to allow for very rapid data entry. Our framework also uses preset response categories, borrowed from existing frameworks or platforms for interoperability, wherever possible.Areas of ongoing and future work include: (a) using the framework to populate a database of IAS removal projects, (b) building an online platform based on the framework and database, allowing users to interact with existing data and submit their own, (c) creating artificial intelligence tools to support data entry, and (d) developing crosswalks with terminology in other frameworks and platforms to maximise interoperability.

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DOI: 10.3897/aca.9.e203641

Authors: Heidi Blom, Sara Byrsten, Ursula Karjalainen, Erja Huusela, Miia Jauni

Abstract: Invasive alien species (IAS) pose a significant threat to biodiversity in northern regions, where climate change is increasingly favoring their establishment and spread over native species. Effective prevention and management of IAS requires coordinated action across administrative borders and governance levels.The Interreg Aurora –funded project BB Alien (2025–2028) aims to strengthen cross-border cooperation between northern Sweden and Finland to improve the prevention, management, and eradication of IAS. The project area covers Finnish and Swedish Lapland, focusing on both sides of the international border along the Tornio River, and it specifically addresses issues unique to the northern context.The project places strong emphasis on awareness-raising related to IAS introduction pathways to prevent their spread to and within the border region. Targeted communication activities, including videos and other outreach materials, are developed for relevant stakeholder groups. In addition, the project enhances professional collaboration and information exchange across the Nordic region by further developing the Nordic IAS network and organizing webinars and other knowledge-sharing events.BB Alien applies a living lab approach to support the eradication of invasive alien plant species and to prevent their further spread through multi-actor collaboration in Sweden and Finland. Researchers, municipalities, landowners, non-governmental organizations, and local communities jointly co-design and implement IAS management actions, exchanging practical experiences in selected riparian environments, including Natura 2000 sites. Target species include Lupinus nootkatensis, L. polyphyllus, Rosa rugosa, and Impatiens glandulifera.The Finnish Living Lab activities are coordinated by Pidä Lappi Siistinä ry, which began its Living Lab work in autumn 2025. The first stakeholder meeting was held in the city of Kemi on 12 March 2026, and field-based pilot work at eradication sites is carried out across several municipalities in Lapland during the summers of 2026 and 2027.The living labs integrate field inventories, collaborative planning, and environmentally sound eradication measures. These include community-led IAS removal activities and the testing of novel control methods, such as hot water treatment for L. polyphyllus. Eradication efforts are supported by citizen engagement tools, communication campaigns, and stakeholder-led implementation. The project aims to develop a transferable and cost-effective model for collaborative IAS management that promotes long-term continuity beyond the project duration. Capacity building through workshops and knowledge-sharing events equips stakeholders—particularly municipalities—with the skills and networks needed to sustain living lab–based IAS management and replicate the model in other regions.The poster will give an overview of the projects Living Lab activities in Finland and Sweden and share experiences from the Finnish Living Lab after its first year working with stakeholders and on the eradication sites.

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DOI: 10.3897/aca.9.e203584

Authors: Rudolf Mremi, Kristofer Chan, Emma Tebbs, Joshua Brian, Abraham Eustace, John Sanya, Jane Catford

Abstract: Plant invasions increasingly threaten biodiversity, ecosystem functioning and local livelihoods worldwide. Yet, formal management responses remain based on Western ecological knowledge with limited integration of traditional ecological knowledge and community perspectives. Overlooking local knowledge can limit the efficacy of “formal” management, weakening interventions by conservation organisations and government agencies. This is especially the case in complex systems where people live closely with the environment. Using a socio-ecological approach, we document traditional ecological knowledge, perceived impacts and community willingness to support invasive plant management in the Serengeti socio-ecological system. In a survey of 229 respondents from six villages adjacent to the Serengeti ecosystem in northwestern Tanzania, about 85% reported being aware of invasive plant species, with awareness shaped by respondent’s education, proximity of their residence to protected area boundaries and experience of invasive plant impacts. Over 75% of respondents demonstrated high knowledge of four target invasive plant species (Chromolaena odorata, Lantana camara, Opuntia stricta and Opuntia ficus-indica), including their spread and traditional management practices. Despite noting some benefits of invasive plants (e.g. used as fencing, boost honey production, serves as fodder), respondents viewed invasive plants as having negative impacts overall (e.g. reducing palatable pastures, lower crop yields). Reflecting these perceptions, 73% of respondents expressed strong willingness to support formal management efforts. However, translating their willingness and local knowledge into effective action requires coordinated strategies. Strengthening coordination mechanisms among protected area authorities, local institutions and adjacent communities can improve adaptive planning and support the development of effective management frameworks. Our findings emphasize the importance of integrating local knowledge systems and community perspectives into formal management of invasive species for effective management strategies.

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DOI: 10.3897/aca.9.e203558

Authors: Alberto Puente-Rolón

Abstract: The introduction of the red-tailed boa (Boa constrictor) to Puerto Rico, first recorded in the early 1990s, represents an increasing ecological threat to the island’s native fauna. This study integrates results from ongoing research addressing the ecology, reproductive biology, and morphological adaptations of this invasive species. More than 1,900 individuals were provided by the Puerto Rico Department of Natural and Environmental Resources between 2011 and 2024. Analyses revealed that the species maintains a female-biased sexual size dimorphism consistent with continental populations, although a slight tendency toward island dwarfism was detected. Dissections indicated reproductive activity throughout the year, suggesting a loss of reproductive seasonality compared to its native range. Dietary analyses identified rodents (Rattus norvegicus and Mus musculus) as the most frequent prey, along with birds and reptiles, confirming its role as a large generalist predator. Furthermore, nocturnal surveys showed no correlation between activity levels and lunar phases, implying continuous foraging behavior. Collectively, these findings demonstrate that B. constrictor is established and well adapted to multiple habitats in Puerto Rico, exhibiting active reproduction, broad dietary plasticity, and ecological traits that may significantly impact native species. The information generated provides a scientific basis for developing management and mitigation strategies aimed at reducing the ecological consequences of this invasive snake.

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DOI: 10.3897/aca.9.e203537

Authors: Sanna Kuningas, Miia Jauni, Erja Huusela, Heidi Blom

Abstract: Invasive alien fish species pose a growing threat to the biodiversity and ecological stability of freshwater ecosystems in Finland. In recent years, new occurrences of alien fish have been detected in natural waters at an accelerating pace, raising concerns about the long-term impacts on native species and aquatic habitats. Once invasive alien fish species become established in large lake systems or interconnected waterways, their eradication becomes virtually impossible due to the scale and openness of these environments. Effective removal measures are generally feasible only in small, closed water bodies, and even in such cases the operations are technically demanding and financially burdensome. Consequently, early detection, prevention, and rapid response are essential for mitigating the ecological risks associated with invasive alien fish species. Despite this urgency, current knowledge on the distribution of invasive alien fish species in Finland relies on citizen observations, which are often spatially uneven and lack systematic coverage.A European Maritime, Fisheries and Aquaculture Fund (EMFAF) funded project (VIKSU) running during 2026-2027, addresses these challenges by piloting the use of environmental DNA (eDNA) sampling in small water bodies across southern Finland. The aim is to evaluate, develop, and operationalize eDNA-based monitoring as a practical tool for mapping the distribution of invasive fish species more comprehensively and reliably than traditional observation-based methods. The project focuses specifically on two species listed as invasive alien species under the EU regulation: the pumpkinseed (Lepomis gibbosus) and Chinese sleeper (Perccottus glenii). Both species are already present in Finland and have demonstrated the capacity to establish themselves in the wild. Pumpkinseed occurs already in at least 50 locations, and Chinese sleeper have been detected in two ponds.By applying eDNA techniques, the project seeks to fill critical knowledge gaps regarding the current distribution and spread of these species in southern Finland. The updated distribution data will enable authorities to identify and prioritize high-risk sites where removal actions should be targeted most urgently, thereby reducing the likelihood of these species expanding into larger lakes and river systems where management would no longer be feasible.In addition to improving species detection, the project establishes a functional data pipeline and a collaborative operational model between the Natural Resources Institute Finland (Luke) and the Economic Development Centres and the Finnish Supervisory Agency. This cooperation framework is essential to ensure that expert-verified information on invasive species is transmitted efficiently to the authorities responsible for implementing eradication and control measures. As part of the project, the Economic Development Centres will also develop standardized guidelines for conducting removal operations. Although the model is piloted specifically for harmful invasive aquatic species, it is designed to be adaptable for managing other aquatic and terrestrial invasive species in the future.The project’s communication efforts target a broad audience ranging from the general public to policymakers. By increasing awareness of the ecological and socio-economic impacts of invasive species, the project aims to foster a more informed and proactive approach to preventing their spread. Ultimately, the project contributes to strengthening Finland’s capacity to detect, monitor, and manage harmful invasive species, thereby supporting the protection of native biodiversity and the resilience of freshwater ecosystems.

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DOI: 10.3897/aca.9.e203423

Authors: Alfredo Maccioni, Vanessa Lozano, Giovanna Spano, Giuseppe Brundu

Abstract: Diachronic vegetation analysis is based on the systematic comparison of data acquired across distinct temporal windows, enabling the quantification of landscape evolutionary dynamics. Vegetation dynamics are often intrinsically slow, and the temporal scales relevant to biodiversity management frequently span several decades. Long-term vegetation dynamics are best studied through monitoring via permanent plots. In recent years, the resurveying of historical vegetation study sites has become increasingly prevalent, as it offers a unique opportunity to estimate vegetational and environmental changes over recent decades. Within the framework of the Project LIFE+ 12/NAT/IT/000416 – Life Puffinus Tavolara — "Protection of the world's largest population of Puffinus yelkouan and control of invasive alien species", co-funded by the European Union and coordinated by the Municipality of Olbia in partnership with the “Tavolara-Punta Coda Cavallo” Marine Protected Area (Olbia, Sardinia, Italy), a key action involved the management of invasive alien species such as feral goat populations and Carpobrotus spp (hereafter IAS). This intervention became necessary to mitigate their negative impact on the local flora. Monitoring of this action was conducted through diachronic vegetation analysis using permanent fenced plots (with dedicated goat exclusion gates). The present study adopts a diachronic approach to compare data collected in 2014, 2016 with data from 2025, at the Tavolara Island, facilitated by the resurvey of permanent fenced plots. The specific objective is to understand how the vegetation has evolved over a period of nearly ten years, spanning the pre- and post-containment phases of the IAS. Furthermore, the study assesses whether significant differences exist regarding: species richness and diversity, floristic composition and plant community structure. Diachronic analysis was performed on two 10 x 10 m permanent plots. In each plot, a census of present taxa was conducted, with each taxon assigned a percentage cover value.

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DOI: 10.3897/aca.9.e203381

Authors: Aidan Clancy

Abstract: Plant invasions are burgeoning worldwide, causing severe ecological and socio-economic impacts alongside sustainable management challenges. Of the many floral invasive species, such as Himalayan balsam and giant hogweed, one species is of particular concern for the western Atlantic, that being Japanese knotweed. Japanese knotweed is a notorious floral invasive species that has spread across much of North America and Europe, with a high reliance on synthetic chemical controls. Conventional herbicides used to manage Japanese knotweed include glyphosate, imazapyr and synthetic auxins, but non-target environmental, human health, and regulatory concerns increasingly require the development of more environmentally sustainable options. This study tested whether extracts from the leaves of native stinging nettles (Urtica dioica) and invasive pontic rhododendron (Rhododendron ponticum), suspended in both water and isopropanol solvents, impacted various growth and viability metrics in non-native Japanese knotweed above- and belowground material over a 9-week controlled experimental period. We found that shooting plants were significantly impacted by treatments applied, with rhododendron extracts typically more inhibitive than nettles, and 100% concentrations stronger than 50% concentration counterparts. These treatments induced up to an 81% reduction to plant height, alongside reduced numbers of nodes, stems and leaves, as well as heightened necrosis indicating impeded viability. Rhizomes, in contrast, were generally not impacted by nettle or rhododendron treatments, but were unexpectedly completely inhibited following the application of isopropanol solvent alone, with no signs of growth and total degradation after solvent applications. These findings suggest that the use of allelochemicals and isopropyl solvents to inhibit the development of Japanese knotweed is viable and allelopathy could be a novel management tool for controlling the spread of this and other invasive plant species.

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DOI: 10.3897/aca.9.e203373

Authors: Valentina La Morgia, Daniele Paoloni, Sandro Bertolino, Adriano Martinoli, Lucas Wauters, Paola Aragno, Gaetano Aloise, Lucilla Carnevali, Piero Genovesi

Abstract: Biological invasions require rapid responses, yet bureaucratic procedures frequently delay action. Although European and Italian regulations (EU Regulation 1143/2014; Legislative Decree 230/2017) mandate rapid eradication of Invasive Alien Species (IAS), a significant implementation gap persists. In Italy, the surveillance system is fragmented, and local authorities frequently lack the specialised expertise and operational capacity for immediate intervention. To bridge this gap, we established the Alien Squirrel Emergency Team (ASET), an expert-led task force designed to convert early warnings into field responses.ASET brings together researchers from the Institute for Environmental Protection and Research and several Italian universities. It was founded within the framework of the LIFE U-SAVEREDS project (LIFE13 BIO/IT/000204) and is focused on the management of alien sciurids. The team operates through a multi-channel monitoring network, integrating data from citizen science platforms, social media, and direct reports from private citizens and local institutions. It functions as an Early Warning mechanism, coupled with expert validation of each record to ensure accurate identification of target species such as Sciurus carolinensis, Callosciurus erythraeus, C. finlaysonii, and C. prevostii.Since 2018, ASET has handled 22 reports across 9 Italian regions using a flexible approach. A key component is the rapid coordination of on-site inspections following opportunistic sightings, as demonstrated by interventions targeting isolated individuals in several localities of northern Italy. Near the Slovenian border, ASET also conducted trained local operators, fostering the transfer of technical skills to regional staff.Beyond initial surveys, the team leverages existing infrastructures, for example, by collaborating with monitoring funded by the National Recovery and Resilience Plan in National Parks and cross-taxa projects like MonitAnt (Biodiversa+) in South Tyrol. These synergies optimise field efforts and maximise detection probability and also illustrates ASET’s capacity to track IAS occurrences over time. An initial report of the American red squirrel (Tamiasciurus hudsonicus) in 2020 was systematically followed up, ensuring that subsequent suspected sightings in the area were prioritised rather than treated as isolated events. Persistent monitoring prevents the loss of critical information during administrative turnovers and supports a long-term strategic understanding of invasion dynamics.Recognising that removal actions often encounter strong public and animal rights opposition, ASET builds on experience from LIFE U-SAVEREDS and the previous LIFE EC-SQUARE project (LIFE09 NAT/IT/000095), to provide support in developing effective communication strategies. By providing expertise on the human dimension of IAS management, the team assist local authorities in anticipating and navigating social conflicts.Moreover, ASET acts as an intermediary between local administrations and international funding opportunities. A recent example is the participation in the IUCN Rapid Response Fund (RRF) call, following the detection of a new C. prevostii nucleus. ASET informed the regional agency of this opportunity and facilitated connections with partners able to manage the application process.Finally, beyond emergency response, ASET contributes to long-term strategic objectives. In some regions, dedicated field technicians operate in close coordination with local institutions and maintain regular contact with ASET members, ensuring continuity between research and management. In southern Italy, the team is investigating the genetic identity of Callosciurus populations and leading the development of new LIFE project proposals. ASET also expanded its scope to international cooperation, for instance, through exchanges with French colleagues on the management of Callosciurus.Ultimately, this case study indicates that bridging the implementation gap requires more than technical expertise; it depends on continuity of information, strategic communication, and cross-sectoral coordination. By integrating these elements, the ASET model consolidates fragmented local efforts into a coherent national approach, providing a transferable framework for IAS management across the European Union.

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DOI: 10.3897/aca.9.e203368

Authors: Rein Brys, Jelger Herder, Teun Everts

Abstract: Invasive species are a major driver of global biodiversity loss, particularly in freshwater ecosystems. The marbled crayfish (Procambarus virginalis), a parthenogenetic invader with exceptional capacity for rapid spread, poses an increasing threat to amphibian communities across Europe. Here we present the implementation of environmental DNA (eDNA)-based monitoring to assess the distribution, ecology, and ecological impacts of this species on native amphibian communities. We developed and validated species-specific digital droplet PCR (ddPCR) assays for sensitive detection and absolute quantification of marbled crayfish and several native amphibians of conservation concern. Mesocosm experiments and field validations demonstrated that ddPCR enables highly sensitive detection and reliable estimation of population size from eDNA samples. Next, we conducted a four-year monitoring program across a large number of ponds and fens in the Hatertse Vennen (the Netherlands), a nature reserve and biodiversity hotspot supporting protected species such as the great crested newt (Triturus cristatus), moor frog (Rana arvalis), and spadefoot toad (Pelobates fuscus). This study revealed that marbled crayfish is far more widespread and abundant than previously assumed, with ongoing annual expansion. Concurrent amphibian eDNA monitoring indicated strong negative effects associated with crayfish presence, including substantial population declines at invaded sites. These findings are now informing targeted management actions, including eradication efforts and the implementation of dispersal barriers designed to limit crayfish spread while maintaining amphibian connectivity. Our study highlights ddPCR-based eDNA monitoring as a powerful tool for invasive species detection, population assessment, and impact evaluation. More broadly, this approach provides a scalable framework for conserving amphibian biodiversity in vulnerable freshwater ecosystems.

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DOI: 10.3897/aca.9.e203367

Authors: Eléna Manfrini, Nicolas Sauvion, Clara Marino, Pierre-Olivier Maquart, Edouard Duquesne, Luc Legal, Olivier Blight, Christophe Hanot, Benoît Geslin, Åsa Berggren, Marion Javal, Elena Angulo, Alok Bang, David Renault, Boris Leroy, Franck Courchamp

Abstract: Insect farming is promoted as a sustainable alternative to traditional livestock, offering substantial reductions in land, water, and feed use while generating fewer greenhouse gas emissions. However, the escape or release of farmed insects into non-native environments may create significant biological invasion risks, with consequences for biodiversity, human well-being, and economies. This study provides the first systematic assessment of the ecological characteristics influencing the likelihood of edible insects becoming invasive, and identifies species not yet reported as invasive that could present risks if farmed outside their native ranges. We evaluated 1,030 species (943 native and 88 introduced) spanning six insect orders (Coleoptera, Lepidoptera, Hymenoptera, Hemiptera, Orthoptera, and Blattodea) in a multidimensional functional space. Our analyses highlight the importance of both larval and adult diet breadth, macroecological factors such as temperature and humidity, and native-range distribution size as predictors of invasion potential. Using machine learning, we identified species with high invasive risk, with Orthoptera, Lepidoptera, Hemiptera, and Hymenoptera being the groups most likely to become invasive. By combining ecological variables with predictive modeling, this work provides a framework for invasion risk assessment and delivers practical guidance to support sustainable insect farming while minimizing ecological threats.

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DOI: 10.3897/aca.9.e203363

Authors: Pablo Gonzalez-Moreno, Javier Galan-Diaz, Ricardo Hernandez-Lambraño, Montserrat Vilà

Abstract: The spread of certain economically important agricultural pathogens depends on complex biotic interactions with dispersal vectors and several host plant species. Therefore, evaluating the areas at risk of infection requires considering all interacting species at play. The bacterium Xylella fastidiosa (Xf) is one of the most threatening plant pathogens in the world. In the Iberian Peninsula, where it has already infested important fruit crops such as olive and almond plantations, Xf is dispersed by two polyphagous spittlebugs that can feed on 161 plant species reported to be infected by the pathogen. The aim of this study is to map high-risk areas prone to Xf infection for targeted prevention measures by considering the spatial explicit distribution of the pathogen, its vectors, susceptible crops and wild plant hosts.We used bioclimatic, soil and land cover data to model the potential distribution of Xf vectors and hosts (both crop and wild plant species) in the Iberian Peninsula and the Balearic Archipelago. Then, we integrated these results with Xf climatic suitability, the distribution of susceptible crops, transport networks and garden center data to identify areas highly vulnerable to Xf infection. We also evaluated how infection prevalence and Xf subspecies-host relationships affect the spatial variation in habitat vulnerability.Two regions of the Iberian Peninsula emerged as most vulnerable to Xf infection. On the one hand, the Balearic Archipelago and East of Spain appeared as highly vulnerable due to the high environmental suitability for Xf and its plant hosts, which are spatially intermingled with susceptible fruit crops such as almond trees. On the other hand, the SW of the Iberian Peninsula was also at high risk due to strong environmental suitability for Xf and its vectors , which indicates high potential of natural spread. Host range diversity influenced the distribution of areas of high risk of infection.Our spatial analysis delivers an integrated framework useful for spatial surveillance aimed at identifying areas at high risk of infection by plant pathogens dispersed by insects. S patially explicit risk assessments of complex pathosystems, need to address the interactions between n ative plant communities and vulnerable crops with their vectors, as well as the overlap among areas able to host multiple pathogen strains.

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DOI: 10.3897/aca.9.e203359

Authors: Ana Cristina Cardoso, Chiara Magliozzi, Emmanuelle Quillerou, Giacomo Montereale Gavazzi, Gregoire Dubois

Abstract: The Knowledge Centre for Biodiversity (KCBD) of the European Commission plays a key role in tracking progress towards the 2030 targets of the EU Biodiversity Strategy and the Kunming Montreal Global Biodiversity Framework (KM GBF). At the same time, it plays a key role in providing capacity building support to European countries in helping monitor and implement the KM GBF. The KCBD serves indeed as main entry point for support requests sent to the European Technical and Scientific Cooperation Support Centre (TSCC) of the UN Convention on Biological Diversity (CBD). The KCBD has been appointed to host and coordinate the European TSCC, in partnership with the Centre for Mediterranean Cooperation of the International Union for Conservation of Nature (IUCN Med) and the Royal Belgian Institute of Natural Sciences (RBINS). Because the TSCC is developing a network of knowledge hubs to support 45 parties (44 countries + the EU as a party) in implementing the KM GBF, this new technical and scientific cooperation mechanism of the CBD provides a unique opportunity to engage with local authorities and stakeholders through knowledge hubs that can provide technical advice, capacity building and governance support.Regarding invasive alien species (IAS), target 6 of the KM GBF calls for a 50 % reduction in the introduction of IAS and for action to limit their impacts. The EU has already incorporated this goal into Target 12 of the EU Biodiversity Strategy and into the EU IAS Regulation (Regulation 1143/2014), which obliges Member States to take action on IAS of Union concern. In this context, JRC supports the development of indicators for Target 6 and uses the European Alien Species Information Network (EASIN) - the official support system for the IAS Regulation- to provide technical and scientific resources for EU-level and global monitoring. JRC has been appointed to manage the knowledge hub focusing on Target 6 where EASIN, an online platform that collects, validates and shares first introduction dates, distribution records and pathway information for IAS of Union concern, is a key component. By analysing these data, EASIN maps trends over time and space, assesses pressure on European ecosystems and provides the evidence needed to track progress towards the EU and global biodiversity targets. Several examples across environments will be showcased during the presentation.

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DOI: 10.3897/aca.9.e203358

Authors: Chiara Magliozzi, Joaquin Vicente Baños, Ana Cristina Cardoso

Abstract: Invasive alien species (IAS) pose a considerable threat to European ecosystems, with the risk of disease spillover from IAS to native wildlife, livestock, and human populations being an increasingly significant concern. Despite heightened research efforts, the complex interactions of factors driving disease transmission from IAS remain poorly understood.A systematic review and analysis of 545 pathogen-host-environment-driver records from 85 studies on invasive alien mammals in Europe was undertaken. The results revealed that ecological and biological factors, such as host density and reservoir host abundance, predominate the dataset (51.7% of records). Additionally, human-driven environmental change (14.1% of records) and pathogen-related factors (21.5% of records) play a substantial role in disease transmission. Notably, the study highlighted considerable variation in factor profiles across different invasive alien mammal species, including the American mink, raccoon dog, and raccoon.The analysis showed that host density was the most frequently documented driver, appearing in 116 records (21.3% of the dataset), followed by reservoir host abundance (7.2%, n = 39) and presence/abundance of other invasive species (5.9%, n = 32). Urbanization and peri-urban expansion were also identified as significant drivers, particularly for species such as the raccoon, which exhibited a strong association with human-driven environmental change (27.3%, n = 30).The study further revealed that the most frequently documented pathogens were *Baylisascaris procyonis* (raccoon roundworm, n = 36 records), *Toxoplasma gondii* (n = 29), Aleutian mink disease virus (AMDV, n = 23), squirrelpox virus (SQPV, n = 20), and SARS-CoV-2 (n = 19). The pathogen assemblage included diverse taxonomic groups and transmission modes, reflecting the broad pathogen reservoir potential of invasive alien mammals in Europe.The findings underscore the necessity for targeted management strategies to mitigate host density, reservoir host abundance, and human-driven environmental change, as well as species-specific and landscape-scale approaches to disease management and control. Furthermore, the study highlights the need for continued research into the dynamics of disease transmission from IAS, including the development of quantitative models to predict the risk of disease spillover and the implementation of effective disease surveillance and monitoring systems.

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DOI: 10.3897/aca.9.e203347

Authors: Jordi López-Pujol, Beñat Orbea, Javier Martínez-Fuentes, Eduard López-Guillén, Carmen Carreño, Neus Nualart

Abstract: Biological invasions represent a growing threat to biodiversity and ecosystems worldwide. The vulnerability of mountain systems—traditionally considered more resistant—has increased due to human activity and climate change, which facilitate the spread of non-native plants to higher elevations. Therefore, understanding these invasions is essential for their prevention and control. The Pyrenees constitute a particularly relevant case, as they are characterized by an exceptional floristic richness resulting from a high diversity of climatic, topographic, geological, and ecological conditions.The Atlas of the Pyrenean Flora (https://atlasflorapyrenaea.eu/), developed within the framework of the cross-border projects FLORAPYR AVANCE and FLORAPYR 3D (funded by the INTERREG POCTEFA program), includes more than 3,600 native taxa with confirmed presence in the mountain range since 1960. In that version of the atlas, alien taxa were also considered (with 462 species), although a more exhaustive curation effort was needed. In this work, a revised, unified, comprehensive, and up-to-date list of alien flora has been compiled; it currently includes more than 700 taxa and will soon be made available to managers and researchers working in the field of biological invasions. Starting from the taxa identified as alien in the aforementioned Atlas of the Pyrenean Flora, this list has incorporated new taxa from multiple sources:recent publications on alien flora in regions encompassing the Pyrenees, such as the checklist of Catalonia published by Aymerich & Sáez in 2019, the technical list produced by Cottaz and collaborators in 2021 for Occitania, and the catalogue of invasive exotic plants compiled by Prud’homme and collaborators in 2021 for the Pyrénées and Midi-Pyrénées region;herbarium data containing material from the Pyrenees;online databases such as the Biodiversity Data Bank of Catalonia (Banc de Dades de Biodiversitat de Catalunya; http://biodiver.bio.ub.es/biocat); anddata from the citizen science platform iNaturalist.In this contribution, in addition to presenting a comprehensive list of alien plants in the Pyrenees, a series of ecological and biological aspects have been analyzed, and the main patterns of geographic and temporal distribution have been established (based on localities and recording dates). A decision tree tailored to the Pyrenean context is further applied to classify taxa according to their invasion status, distinguishing between casual, naturalized, and invasive species.The initial results, in addition to indicating that the Pyrenees can be considered a hotspot of alien flora within the context of European mountain systems, highlight the need to implement prevention, detection, and control measures to avoid the spread and introduction of alien plants across the Pyrenean territory and to reduce their potential impact on native species and ecosystems. Future work (to be completed by 2027) will focus on modelling the invasion potential of alien species under projected climate change scenarios and quantifying the impacts of the most concerning taxa on native species and ecosystems using standardized assessment frameworks (e.g., EICAT).

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DOI: 10.3897/aca.9.e203289

Authors: Soria Delva, Damiano Oldoni, Laura Abraham, Louise Hendrickx, Frédérique Steen, Mark Gillespie, Toke Thomas Høye, Katharina Dehnen-Schmutz, Helen Bayliss, Quentin Groom, Nico Noé, Lars Dalby, Kavi Mellerup, Tim Adriaens, Bram D'hondt

Abstract: Early detection of invasive alien species (IAS) is one of the major factors determining their management feasibility. As part of the EU Horizon project OneSTOP, several systems and tools for the early detection and monitoring of IAS are currently being developed and evaluated at different locations in Europe. Here, we focus on two specific systems: the CamAlien and a cross-realm European early alert system. The CamAlien is a vehicle-mounted camera that combines image capture with deep learning-based species identification to detect invasive plants along roads and waterways. It captures high-quality images at speeds of up to 130 km/h, allowing large-scale monitoring over short timeframes. We present preliminary results from CamAlien deployments in Flanders (Belgium), highlighting the system’s performance and its current limitations. The second tool builds on the LIFE RIPARIAS early alert system, expanding its geographic scope to the European level as part of a joint effort between the OneSTOP and GuardIAS EU Horizon projects. It uses occurrence data from GBIF to generate automated notifications of new IAS records within selected regions of interest, thereby supporting rapid management responses. Both the early alert system and the CamAlien are currently being tested by stakeholders in Living Labs across Europe. By combining stakeholder feedback with detection results, we identify opportunities and challenges for including these emerging detection tools into IAS monitoring and management frameworks.

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DOI: 10.3897/aca.9.e203250

Authors: Renata Gonçalves, Clarisse Vilarinho, Joana Cruz, João Monteiro, Vânia Baptista, Cátia Marques, André Cabrita, Maria Teodósio, Pedro Pousão-Ferreira

Abstract: The management of invasive decapods, such as the Atlantic blue crab (Callinectes sapidus) and the European green crab (Carcinus maenas), requires innovative strategies that align ecological removal with economic sustainability. The SoftCrab Project evaluates an "Incentivized Harvest" model based on capturing wild individuals and maintaining them in captivity until molting, testing the technical feasibility of soft-shell crab production as a control method. This case study presents experimental results on nutritional and thermal optimization, identifying the biological bottlenecks that govern this transition from an invasive threat to a commercial resource.In nutritional trials (Standard Diet, Formulated Feed, and No Feeding), C. maenas showed high vulnerability to starvation (78% mortality), a rate significantly higher than those observed in the Standard Diet (25%) and Formulated Feed (44%) groups. Conversely, C. sapidus demonstrated remarkable robustness and digestive plasticity, maintaining low mortality (5.6%) and high trypsin levels even under food deprivation - traits that likely facilitate its invasive success. Concurrently, thermal trials on C. maenas (16ºC, 20ºC, and 24ºC) challenged the hypothesis that higher temperatures accelerate production. While mortality at 16ºC was relatively low (22%), exposure to elevated temperatures (20-24ºC) increased mortality to 59% and penalized post-molt biomass increments without reducing the inter-molt period, which remained excessively long for commercial viability in the tested size classes.Proximal analysis further validated the resource's value, showing that standard culinary processing preserves nutritional integrity. Results revealed a significant contrast between localized tissue and the whole edible organism: while claw muscle provides a lean protein source (>80% DM; ~2% fat DM), the total soft tissues - simulating the edible profile of a soft-shell crab - offer a lipid-dense and calorie-rich profile (~60% protein DM; 9–14% fat DM).Our findings conclude that while C. sapidus shows superior physiological resilience for captivity, biological "resistance" to molting remains a primary barrier for both species. For market-based mitigation to succeed, management must move beyond simple husbandry toward advanced biotechnological interventions to synchronize molting cycles. This study provides a realistic roadmap for integrating IAS control into the blue economy, emphasizing the need to respect species-specific physiological thresholds.

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DOI: 10.3897/aca.9.e203223

Authors: Vera Stanković, Dragana Marisavljević, Danijela Šikuljak, Ana Anđelković

Abstract: Euphorbia davidii Subils (toothed spurge) is an annual herbaceous plant species native to North America (USA and Mexico) that has become widely introduced across the EPPO region, Australia, and Argentina. In recent years, its phytosanitary importance within the EPPO region has increased significantly, reflected in its inclusion in the A2 List of pests recommended for regulation in 2025. In Serbia, E. davidii was first recorded in northern Serbia (Vojvodina Province) in 2007, occupying approximately 3 ha of arable land. By 2013, its distribution had expanded to around 7 ha, indicating an early phase of local spread. Our aim is to provide further insight into the invasion dynamics and habitat preferences of E. davidii in Serbia. Over the period of two consecutive years (2024-2025) area where E. davidii was initially recorded were observed. For each observed population of E. davidii phytosociological relevés were collected and habitat type was determined following the EUNIS classification. Field studies have shown that by 2024 the species had successfully established in semi-natural habitats adjacent to the original record site, particularly along field margins and country roads. Our findings show that the spread of E. davidii had intensified in recent years, with new populations detected at four additional field sites in 2025. The species demonstrated further expansion into semi-natural habitats, such as acacia-dominated thickets, nearby arable crops (corn and rapeseed), as well as grassland strips. Although populations in actively managed fields may be temporarily reduced by agricultural practices (e.g., plowing), its persistence and expansion in less disturbed habitats contribute to an overall increase in invaded area, currently reaching approximately 20 ha. Phytosociological relevés revealed variable population densities (2–50 individuals per 25 m² plot), with dense stands (>80% cover) occurring in open, dry, and sun-exposed environments. These findings confirm a clear shift from cultivated fields into surrounding habitats, including forest remnants and herbaceous vegetation strips. Three main vegetation types were identified:narrow strips of acacia forests and coppices (EUNIS T1J),arable crop fields (EUNIS V11), andremnants of dry grassland vegetation on field edges (EUNIS R1).Across these habitats, E. davidii frequently co-occurred with other invasive species, particularly Sorghum halepense (L.) Pers. and Ambrosia artemisiifolia L. Overall, the results highlight the species’ ecological plasticity and its capacity to exploit both anthropogenic and semi-natural habitats, facilitating its continued spread in agricultural landscapes.

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DOI: 10.3897/aca.9.e203031

Authors: Erika Bazzato, Arturo Cocco, Ignazio Floris, Alberto Satta, Michelina Pusceddu

Abstract: Whether climate change will facilitate or constrain invasive alien species (IAS) remains a central unresolved question in invasion science, particularly in Mediterranean biodiversity hotspots where warming and aridification may alter invasion trajectories in non-linear ways. Robust local-scale forecasts are often limited by coarse environmental data, heterogeneous sampling effort, and spatial autocorrelation, reducing their reliability for management applications.Here, we developed a high-resolution climatic suitability forecasting framework for the alien European hornet Vespa crabro in Sardinia (Italy) (Pusceddu et al. 2019; Pusceddu et al. 2022), a Mediterranean island where the species was introduced in 2010 and currently shows a limited but expanding distribution in the northern sector. We integrated 303 spatially filtered and validated citizen-science occurrences, 40-m island-specific bioclimatic predictors, kernel density-based bias surfaces for pseudo-absence selection, spatial block cross-validation, and three tuned machine-learning algorithms (Artificial Neural Network (ANN), Gradient Boosting Machine (GBM), Random Forest (RF)) replicated across pseudo-absence sets and spatial folds (150 individual models) (Phillips et al. 2009; Barbet‐Massin et al. 2012; Hijmans 2012; Roberts et al. 2017; Valavi et al. 2019). Individual models were filtered using performance thresholds (Receiver Operating Characteristics (ROC) and its Area Under the Curve (AUC), AUC ≥ 0.7; True Skill Statistic, TSS ≥ 0.4), then weighted by validation performance and averaged into an ensemble forecasting model to project current and future suitability under SSP2-4.5 and SSP5-8.5 scenarios for 2040 and 2060. The obtained ensemble model was evaluated using the above-mentioned evaluation metrics and plotting the ROC curve.The final ensemble achieved high predictive performance (ROC = 0.95 ± 0.02; TSS = 0.78 ± 0.06), with Annual Mean Temperature and Precipitation of the Driest Month accounting for 61% of model contribution. Current projections identified extensive climatically suitable habitats across northern Sardinia, most coastal areas, surrounding small islands, and several inland mountainous sectors not yet colonized. In contrast, all future scenarios predicted strong range contraction, with climatically suitable habitat declining by 91.02–98.98% depending on scenario and time horizon, primarily through loss of coastal suitability.These projections suggest that future Mediterranean warming and altered precipitation regimes may progressively exceed the favorable climatic envelope of V. crabro, likely constraining rather than promoting its long-term persistence and spread in insular Mediterranean systems (Fig. 1). More broadly, our findings challenge the widespread assumption that climate change universally enhances invasion risk and highlight the need for species-specific, fine-resolution forecasting to support adaptive surveillance, prioritization, and management of invasive species under climate change.Beyond this case study, the proposed workflow demonstrates how citizen-science data, bias-aware pseudo-absence generation, spatially explicit validation, and ensemble forecasting can be integrated into reproducible invasion-risk assessment frameworks for operational decision support.

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DOI: 10.3897/aca.9.e203218

Authors: Simon Reynaert, Niels Billiet, Pavel Pipek, Ana Novoa, Philip Hulme, Sofie Meeus, Quentin Groom

Abstract: Accelerating detection of invasive alien species (IAS) spread is becoming increasingly important to more effectively allocate the limited resources available for their management. One largely untapped secondary data source lies in the automated tracking of internet activity such as IAS search intensity or mentions across internet platforms. We evaluated the feasibility of tracking IAS spread into new EU countries by combining data from multiple internet platforms covering 88 IAS of European concern. In total, 14 platforms were screened and evaluated based on data accessibility and mined data quality. Our investigation indicates that access to minimal data required for IAS tracking (i.e., information about location, time and place) is overall quite limited and particularly difficult without incurring significant costs for many of the larger platforms (X, Google and Tiktok). From the explored species, more active and easily recognizable taxa (i.e., mammals) overall gained more online traction than more cryptic ones (i.e., plants), though online activity of the former proved a less reliable representation of real-world occurrence patterns. Additionally, while the final five selected internet platforms showed increased activity surrounding the year of invasion in many of the explored invasion scenarios (particularly Wikipedia and Facebook), we found inconsistencies between species groups and trends per platform. We conclude that online platforms show potential as a complementary data source for IAS occurrences but limited access points, variable data quality, limited data validation capacities and privacy legislation currently hinder the creation of fully automated data mining and publication pipelines.

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DOI: 10.3897/aca.9.e203210

Authors: Jesse Beyer, Johan van Valkenburg

Abstract: Highly problematic invasive alien plant species have multiple pathways for introduction into new areas, both intentionally and unintentionally. For Europe, one of the main pathways is via horticultural trade. Although escape from gardens is a well known problem of formerly horticultural plants, like Reynoutria japonica (Polygonaceae), there is also the lesser-known risk of contaminants from invasive plants in plants for planting. When looking at the Union list of invasive species (Regulation 1143/2014), it is known that multiple plant species make use of this pathway. Occasionally they are found in potted plants imported from Central America, like Parthenium hysterophorus (Asteraceae) which was intercepted in the Netherlands in a Coffea arabica from Honduras (EPPO 2016b). Most Union list species however, can be found in so called “pseudobonsai” plants imported from Asia (EPPO 2024). These pseudobonsai plants tend to stay for a longer period at the production and exporting acility in the country of origin and are most often shipped with so called growth medium. Because of these two factors, the chance is higher that an invasive plant can end up in the bonsai plant and is shipped to the country of import. Before the current study four Union list species have been found in the Netherlands as weed in pseudobonsai plants from Asia, namely Alternanthera philoxeroides (Amaranthaceae), Humulus scandens (Cannabaceae), Lygodium japonicum (Schizaeaceae) and Persicaria perfoliata (Polygonaceae). Meanwhile, in the risk assessment for Microstegium vimineum (Poaceae), this pathway was listed as very likely to occur, but until this study the species was never found in Europe (EPPO 2016a).In 2022 and 2025 there where two surveys in the Netherlands to investigate which Union list species occur as weed in plants for planting, what the origin region is and in which potted plant it grows as weed. More in general we were also interested in which other weeds grow in potted plants and if there are patterns regarding origin and host plant. When combining the two surveys a total of 1074 weeds have been sampled, raised in a greenhouse and, if possible, identified both morphological and with DNA. Over 250 different species were identified spread across 73 families, from small herbs to climbers and even what would have become a large tree. Many of these species were never found in earlier projects and will be included in an online multi-access identification key.Of the previously intercepted Union list species, Alternanthera philoxeroides, Humulus scandens and Lygodium japonicum were found. All of them with China as country of origin and mostly in pseudobonsai plants, with one exception of A. philoxeroides found as weed in Poenix palms at one company. Beside these already known Union list species, Broussonetia papyrifera (Moraceae) was also found, again with China as country of origin. Lastly, at the end of 2025 after a growth period of more than half a year a broadleaved grass came in to flower. The sample was taken from a very expensive true Pinus bonsai from Japan. To our great surprise this grass was morphologically identified as Microstegium vimineum Fig. 1, with a confirmation on DNA. This is for the first time that this plant was found in Europe. Findings like these shows that we need to keep inspecting this type of bonsai companies for invasive alien plants.

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DOI: 10.3897/aca.9.e203044

Authors: Jairo Mendoza-Roldan, Gianpaolo Montinaro, Mario Alves, Domenico Otranto

Abstract: Invasive alien snakes pose an increasing ecological and sanitary risk, being potential reservoirs and dispersers of pathogens that can affect wildlife, domestic animals, and humans. As biological invasions accelerate due to globalization and the exotic pet trade, the epidemiological role of non-native species has come under increased investigation. Recent epidemiological research of established populations—such as Burmese pythons (Python bivittatus) in the Greater Everglades ecosystem and California kingsnakes (Lampropeltis californiae) in Gran Canaria—have identified a wide and alarming diversity of microorganisms of significant zoonotic concern.Current literature extensively highlights the high prevalence of zoonotic enteric bacteria in these invasive predators. Most notably, invasive snakes frequently harbor multi-drug resistant (MDR) strains of Salmonella enterica, posing a severe public health risk via direct handling or the contamination of shared environments. Alongside Salmonella, studies have identified these reptiles as shedding sources for Campylobacter spp., Yersinia enterocolitica, Pseudomonas aeruginosa, and Escherichia coli. Furthermore, the recent detection of the emerging, multi-drug resistant fungal pathogen Candidozyma auris) in reptilian hosts raises critical alarms regarding the potential for wildlife to serve as environmental maintenance reservoirs for urgent global human health threats.Beyond bacterial and fungal agents, invasive snakes are potent dispersers of zoonotic parasites and vectors. Recent ecological health assessments underscore the introduction and rapid spillover of novel parasites, such as the respiratory pentastomid Raillietiella orientalis from Burmese pythons to native herpetofauna, carrying broader implications for zoonotic visceral pentastomiasis. The gastrointestinal tracts of these invaders also frequently shed zoonotic protozoa (including Cryptosporidium and Entamoeba species) and helminths (oxyurids, ascarids), which can contaminate local watersheds. Additionally, non-native snakes introduce and sustain exotic ectoparasites, such as non-endemic ticks, which can act as competent vectors for rickettsial and other blood-borne pathogens affecting human and veterinary health.These findings collectively emphasize the profound capacity of invasive snakes to introduce novel pathogens, amplify endemic disease cycles, or facilitate bidirectional spillover events within native ecosystems. To mitigate these multifaceted risks, a One-Health framework is essential. By integrating active wildlife health assessments, advanced genomic sequencing, environmental DNA (eDNA) monitoring, and public-health survelliance, this approach enables the early identification of emerging zoonotic threats. Ultimately, systematic and cross-disciplinary monitoring represents a critical preventive tool to safeguard global biodiversity, prevent the establishment of novel pathogens in naïve ecosystems, and formulate evidence-based mitigation strategies to reduce exposure risks for both humans and animals.

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DOI: 10.3897/aca.9.e203016

Authors: Franz Essl, Ingo Kowarik, Ana Novoa, Arnau Bosch-Guiu, Giuseppe Brundu, Paula Gervazoni, Theresa Henke, Ingolf Kühn, Uwe Starfinger, Montserrat Vilà, Petr Pyšek

Abstract: While the influential role of scientific associations in shaping research fields is well recognized, their impact within the domain of invasion science remains underexplored. This review combines qualitative narrative with quantitative metrics to trace the development of Neobiota, the first European non-profit and non-governmental scientific association dedicated to the study of biological invasions. Since its foundation in 1999, the Neobiota network has aimed to foster scientific exchange and collaboration, advance and integrate research across all dimensions of invasion science, and disseminate findings to support evidence-based policies. Evolving rapidly from a German working group into Europe’s leading network for invasion science, Neobiota has united researchers and practitioners across disciplines, taxa, and national boundaries. In contrast to many other associations, Neobiota operates with a low-threshold, non-bureaucratic governance model, promoting inclusivity and cross-border engagement. We document how its biennial conferences—hosted in twelve European countries between 2000 and 2024—have supported thematic diversity (ranging from molecular biology to socio-economy), increasing international participation (from nine to 47 countries globally), and active policy outreach. Thematically, the focus of research presented at conferences has shifted over time from ecological patterns and species inventories to environmental impacts, predictive modelling, management strategies, and socio-political dimensions of invasions. Trends in equity reveal progress towards gender parity among keynote speakers and session chairs. Neobiota has also supported the dissemination of knowledge through two publication platforms: the Neobiota series (2000–2008), and the open-access, peer-reviewed journal NeoBiota launched in 2011. This journal currently operates under an innovative editorial model with 75 subject editors and a team of five Co-Editors-in-Chief. We conclude that over the past 25 years, Neobiota has been instrumental in building a cohesive and inclusive scientific community globally, advancing and disseminating interdisciplinary research on biological invasions, and informing policy, particularly in support of legal frameworks to prevent and mitigate the negative impacts of non-native species.

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DOI: 10.3897/aca.9.e202999

Authors: Ileana Herrera, Kevin Panchana, Anahí Vargas, Isabella Dillon, Amelia Arcos-Andrade, Estefany Goncalves, José Ferrer-París, Jordi López-Pujol

Abstract: Protected areas (PAs) are central to biodiversity conservation, yet they are increasingly exposed to biological invasions. In continental Ecuador, information on non-native terrestrial spermatophytes in PAs remains scattered across biodiversity platforms, scientific and grey literature, and management documents, limiting broad-scale assessments and management planning. We compiled, validated, and integrated records of non-native terrestrial spermatophytes across 68 continental PAs of the Ecuadorian National System of Protected Areas (Sistema Nacional de Áreas Protegidas, SNAP its Spanish acronym) using GBIF, iNaturalist, peer-reviewed and grey literature, official management plans, and complementary field observations. Records were taxonomically standardized, curated, and assigned to individual PAs. To explain variation in non-native richness, we evaluated predictors grouped into four categories:PA basic attributes (e.g., extent, year of PA designation),propagule pressure and introduction pathways,anthropogenic disturbance, andabiotic environmental conditions.Total non-native taxon richness was modelled using generalized linear models (GLMs). We compiled and validated 3,480 occurrence records, including 2,117 observations from citizen science platforms, 687 herbarium specimens, 371 records from peer-reviewed articles, 123 field observations, 106 thesis records, and 76 inventory records derived from management documents. These records represented 486 non-native taxa from 86 families and 320 genera. Poaceae (55 taxa), Asteraceae (38), and Fabaceae (37) were the richest families, together accounting for approximately 27% of all non-native taxa. Across the full dataset, 204 taxa were recorded only in the wild, 188 only as cultivated, 90 in both conditions, and four remained uncertain in establishment status. Seventeen (25%) PAs had no recorded non-native taxa, whereas Pululahua Geobotanical Reserve and Cayambe-Coca National Park were the richest, with 174 and 172 taxa, respectively. Nearly half of all taxa (47.3%) were recorded in only one PA, while the most widespread taxa, Taraxacum sect. Taraxacum and Trifolium repens, occurred in 17 PAs each. Our dataset included four of the species listed among the world’s worst invasive alien species: Arundo donax, Leucaena leucocephala, Rubus ellipticus, and Spathodea campanulata. The selected GLM identified year of PA designation, extent, distance to the nearest urban area, human density, road density, median human impact, terrain ruggedness, and management type as the main predictors of non-native richness. Richness increased with time since PA designation, extent, road density, median human impact, and terrain ruggedness, while state-managed PAs showed lower expected richness. These results indicate that non-native spermatophytes richness in PA is strongly shaped by propagule pressure, human accessibility, and landscape complexity. Notably, richness increased with time since PA designation, a pattern that contrasts with expectations and may be associated with cumulative introduction history or differences in sampling effort among PAs. This study provides the first integrated national baseline of non-native terrestrial spermatophytes across continental Ecuadorian PAs. By combining heterogeneous data sources into a standardized workflow, it provides a practical foundation for surveillance, early detection, and prioritization of management in a biodiverse yet under-assessed PA network.

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DOI: 10.3897/aca.9.e202987

Authors: Arnau Bosch-Guiu, Julian W. Zeller, Pablo Gonzalez-Moreno, Paula Gervazoni, Theresa Henke, Cristina Acosta-Muñoz, Suneeta Bhatta, Lucas Borges de Lima, Ricardo Enrique Lambraño, James Hardwick, Ileana Herrera, Yves Klinger, Adrián Lázaro-Lobo, Alba-Cristina Linares, Eduard López-Guillén, Javier Martínez-Fuentes, Maria Magdalini Mertzimeki, Gaia Micco, Sara Navarro-López, Kevin Panchana, Zarah Pattison, Stephanie Payne-Smith, Petr Pyšek, Katherine Onoszko, Beñat Orbea, Wolf-Christian Saul, Ross Shackleton, Sandy-Lynn Steenhuisen, Ana Novoa

Abstract: Mountain regions worldwide harbour key and unique biodiversity, yet they are increasingly threatened by multiple human pressures projected to intensify throughout the 21st century. While invasive species are widely recognized as one of the main drivers of global biodiversity loss, until recently, their pressure in alpine and montane systems remained relatively low. But recent evidence suggests that this situation is changing. Climate warming, land-use change, pollution, and increasing rates of alien species introductions are enabling invasive plants to expand into previously less disturbed mountain habitats. Understanding the mechanisms behind this process is essential for predicting future invasions and preventing their impacts.In this study, we assess the magnitude and mechanisms of the negative environmental impacts caused by alien plant species in mountain ecosystems worldwide. Specifically, we obtained a list of 564 species recorded as naturalized across 18 mountain regions, from standardized road surveys along elevational gradients conducted by the Mountain Invasion Research Network (MIREN). We evaluated these species using the Environmental Impact Classification for Alien Taxa (EICAT), an objective and transparent method recognized by the IUCN. EICAT classifies alien species according to the severity of their impacts on native species populations and allows for the classification of the mechanisms driving these impacts. Documented impacts occurring in both mountain and non-mountain ecosystems were included in the assessment.Our preliminary results suggest that empirical evidence on the environmental impacts of most alien plant species remains limited or entirely lacking, particularly in mountain environments. For the species with available information, the most frequently reported impact mechanisms include competition with native species as well as indirect effects mediated through interactions with other organisms (such as disruption of pollinator networks) and allelopathic effects. Overall, this study provides a global overview of the potential impacts of alien plants in mountain ecosystems and establishes a robust scientific foundation for prioritization and the development of targeted management recommendations.

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DOI: 10.3897/aca.9.e202982

Authors: Jasmijn Hillaert, Heleen Van Ransbeeck, Dries Bonte, Jim Casaer, Bram D'hondt, Nicolas Pardon, Diederik Strubbe, Tim Adriaens

Abstract: The invasive yellow-legged hornet (Vespa velutina), listed as a species of Union concern under Regulation (EU) No 1143/2014, has rapidly expanded across Europe since 2004. It impacts human health, biodiversity, and agriculture. Understanding its population dynamics is essential for designing effective management strategies. In recent years, citizen science initiatives have generated large datasets that can support quantitative modelling of the population.We developed an individual-based population model for V. velutina using long-term data from the Vespa-Watch platform in Flanders (Belgium). The model was parameterized using annual counts of nests recorded since 2016. By simulating the life cycle of queens and their contribution to population growth, the model allows us to explore the effects of current management efforts on population development, as well as future population trajectories under different management scenarios across space (at level of Flanders, provinces or municipalities) and various intensities of nest removal.Our results highlight the value of citizen science data alongside the reporting of management interventions for modelling the dynamics of invasive species and for evaluating management strategies. The modelling framework provides a quantitative tool to assess the effectiveness of control measures and supports evidence-based management of V. velutina populations in Flanders and elsewhere in Europe.

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DOI: 10.3897/aca.9.e202968

Authors: Pieter Boets

Abstract: Invasive alien crayfish have become a widespread challenge in freshwater ecosystems across Europe, where their impacts extend beyond species-level effects to influence entire ecosystem functioning. While monitoring and detection remain essential components of management, increasing attention is being directed towards ecosystem-based approaches that address the underlying conditions facilitating crayfish establishment and impact.Experiences from both Belgium and the Netherlands demonstrate that long-term management success is unlikely to be achieved through direct control measures alone. Intensive trapping and other population reduction techniques can contribute to local impact mitigation but rarely result in sustained population suppression at larger spatial scales. Instead, management is increasingly shifting towards integrated strategies that combine targeted control with ecological restoration, habitat management and biological control.A key lesson learned is the importance of restoring ecosystem resilience. Improving water quality, enhancing habitat diversity, and supporting healthy aquatic food webs can strengthen the resistance of freshwater ecosystems to invasive crayfish impacts. Recent experiences in the Netherlands suggest that nature-friendly riverbanks and riparian habitat restoration may contribute to lower crayfish densities by promoting more diverse and resilient aquatic communities and improving habitat conditions for native species. Particular attention is also being given to the role of predators, including native and established fish species, which may contribute to regulating crayfish populations as part of a broader ecological balance. Although predator-based control is not a standalone solution, it illustrates how biotic interactions can be incorporated into integrated management frameworks.The comparison between Belgium and the Netherlands highlights differences in management approaches, governance structures, and implementation pathways, while also revealing common challenges. In both countries, successful management increasingly depends on collaboration between water managers, conservation agencies, researchers, and local stakeholders, as well as on aligning invasive species management with broader ecological restoration objectives.Recent experiences underline the need to move from species-focused control towards area-based and ecosystem-oriented management. By combining prevention, targeted intervention, habitat restoration, water quality improvement, and the reinforcement of natural ecological processes, management efforts can contribute not only to reducing crayfish impacts but also to enhancing the overall ecological condition of freshwater systems. These lessons provide valuable perspectives for the future development of invasive crayfish management across northwestern Europe.

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DOI: 10.3897/aca.9.e202964

Authors: Paul Brett

Abstract: Vespa velutina (Hymenoptera: Vespidae; Lepeletier, 1836) recently arrived on the island of Ireland in 2025, where three nests were identified and removed. Prioritising management is critical given its documented impacts on native Diptera, Hymenoptera, and pollinator populations across Europe. A greater understanding of current climate suitability, identification of the potential spread across the island of Ireland and priority risk sites would be beneficial to guide the future management of this species.The initial aim was to identify the regions on the island of Ireland that would be climatically suitable for this species to survive and proliferate in. This would require species distribution models to be developed using occurrence data from GBIF and other collections incorporating ERA5 climate data for the most recent climate normal (1991–2020) and subsequent years. The inclusion of more recent climate data would allow assessment of whether climatic conditions in Ireland have become more suitable in recent years.The secondary aspect to assess is the potential spread of this species via man-made infrastructure and biological means by utilizing agent-based models using previously identified criteria from other European countries. Spread was simulated from previous nest locations in three locations to assess the spread if management measures had not been undertaken. It was later assessed from other locations across the country whereby if a nest were to be found there what would be the pattern of spread over time. It is envisioned that this framework will inform management decisions relating to Vespa velutina under an adaptive response strategy under current climate and with expected repeated introductions.

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DOI: 10.3897/aca.9.e202960

Authors: Alisha Higgins, Paul Wood, Kate Mathers

Abstract: In the UK, the network of navigable canals spans over 2000 miles and provides habitat for a wide diversity of wildlife (Canal & River Trust 2026a, Canal & River Trust 2026b); Canals support a variety of physical habitats from lightly managed rural to heavily modified urban locations (Gurnell et al. 2025). However, canals are underrepresented in the UK’s freshwater ecological research particularly in relation to the macroinvertebrate diversity they support, despite being unique but widespread habitats (but see The Ponds Conservation Trust: Policy & Research 2003; Walker and Hassall 2021; Bibi et al. 2022). A potential threat to the biodiversity of macroinvertebrates within canal ecosystems are invasive non-native species (INNS) (Jackson et al. 2014). Freshwater invasive macroinvertebrates are particularly common in artificial waterbodies, and especially canal systems, and include the signal crayfish (Pacifastacus leniusculus), Asian clam (Corbicula fluminea), zebra and quagga mussel (Dreissena polymorpha; Dreissena bugensis), and demon, killer and bloody-red shrimp (Dikerogammarus haemobaphes; Dikerogammarus villosus; Hemimysis anomala), which have been introduced either intentionally or unintentionally through human activities such as fishing, aquaculture and boating (Hulme et al. 2008; Keller et al. 2011). The mechanism of successful establishment of these invertebrates will differ depending on their functional characteristics. However, the increased connectivity of waterbodies offered by canals is likely to facilitate their movement across the landscape (Wohl 2017). Despite being a potential hotspot for INNS, currently there are no studies that have specifically considered the distribution of invasive invertebrates in canals in the UK. This research gap is being directly addressed using the Grand Union Canal and adjacent rivers within Leicestershire (UK) as a case study. The composition of the macroinvertebrate communities has been characterised, alongside the presence of INNS. This research project will provide evidence of the composition of macroinvertebrate communities in canals and discuss the potential role of waterbody connectivity in facilitating the range expansion of invasive invertebrate species.

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DOI: 10.3897/aca.9.e202850

Authors: Albert Medina, Alba Sevilla-Navarro, Federica Rossetto, Belinda Gallardo

Abstract: Freshwater ecosystems are disproportionately affected by biological invasions (Gallardo et al. 2015; Moorhouse and Macdonald 2014), yet knowledge of freshwater alien species and their potential impacts remains limited (Thomsen et al. 2014) and scattered across databases, many of which only cover certain taxa or geographic regions. To address this gap, we developed FRIAS, a reproducible workflow to generate the first global dataset dedicated to freshwater alien species.We showed that freshwater ecosystems contain a disproportionately high richness of alien species relative to their global surface area. Of all 3,576 recorded species, approximately 75% were animals (47% vertebrates and 28% invertebrates), while 16% were vascular plants (Fig. 1).Vertebrates and vascular plants were predominantly introduced as commodities through intentional pathways, whereas invertebrates were mainly introduced unintentionally via ship transport. Most introduced species originated from North America and Asia, and the Americas and Western Europe represented the primary recipient regions. The countries sharing the greatest number of species were those in North America (the United States, Canada, and Mexico). The global accumulation of alien species over time followed an exponential trend, with notable increases in introduction rates occurring in the early and late 19th century, as well as in the mid-20th century. Interestingly, the annual rate of new introductions at the country level declined notably at the beginning of this century, likely due to reporting lags, and the saturation of the species pool and their potential range. Of the 458 species with documented impacts, 315 (69%) were classified as invasive based on their impact severity. Among assessed taxa, vascular plants had the strongest impacts, whereas amphibians showed the weakest.Overall, this work provides the first integrated global assessment of spatiotemporal patterns and impacts of freshwater alien species, establishing a baseline for further exploration of large-scale patterns in freshwater invasions.

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DOI: 10.3897/aca.9.e202937

Authors: Maud Segal, Teun Everts, Loïc van Doorn, Jeroen Speybroeck, Rein Brys, Tim Adriaens

Abstract: The non-native invasive African clawed frog (Xenopus laevis) poses a severe threat to native aquatic biodiversity worldwide. In Europe, its northernmost introduced population has established a stronghold along the French-Belgian border. While the earliest documented record in Belgium dates back to 2006 (though only made public in 2019), the discovery of a population in la Chapelle-d’Armentières (in northern France) in 2018 highlighted an impending transboundary threat. By 2021, the species’ presence was confirmed in both Flemish and Walloon regions of Belgium.To delineate the spatial extent of this invasion, extensive environmental DNA (eDNA) monitoring campaigns were conducted in 2020, 2022 and 2023, in the context of an early-detection-rapid response program. A novel “pooled” eDNA sampling strategy was developed, combining water from multiple sites into single filters to maximize spatial coverage while minimizing analytical costs (Everts et al., 2025). This effort revealed an interconnected transboundary population spanning an occupied area of 103 km². The eDNA results not only revealed a more widespread occurrence than previously thought, it also fundamentally shifted our understanding of their dispersal, underscoring the critical role of lotic systems as primary corridors facilitating cross-border migration. Furthermore, absolute X. laevis eDNA concentrations allowed us to differentiate between ponds with low incidental presence (18% of sampled sites) and those with high concentration indicative of active reproduction (6%). The relatively low percentage of high-concentration ponds indicate complete eradication may still be within reach.Shortly after detection, rapid eradication efforts were evaluated to eliminate key breeding ponds. Two primary methodologies were tested: quicklime (calcium oxide) application and intensive fyke trapping. Quickliming proved highly effective for rapid, whole-system population removal by temporarily elevating water pH to lethal levels. While it offers the advantage of breaking down into naturally occurring minerals, its non-selective nature makes it unsuitable for habitats supporting protected native species. Furthermore, it requires substantial logistical effort. Conversely, benthic entrapment using fyke nets effectively targets X. laevis while minimizing native by-catch. However, trapping is too inefficient and time-consuming in high density ponds. Given the scale of the invasion, a coordinated eradication project was launched in early 2026, supported by the IUCN rapid response fund. This collaboration unites stakeholders from Flanders (INBO, ANB) and Wallonia (SPW, CREL) to systematically treat colonized ponds and the river system. Management is prioritized on breeding ponds and from West to East to prevent dispersal into the adjacent pristine Yzer river basin. Utilizing a context-tailored approach, the strategy for ponds integrates pond filling, physical barrier installation, fyke netting, drainage and quickliming. Passive barriers at critical points in the stream are used to lower dispersal probability. With these collections of efforts, we hope to at least contain the invasion, and hopefully contribute to its complete removal in the long term.Everts T, van Doorn L, Adriaens T, Neyrinck S, Kerckhofs K, Speybroeck J, Brys R (2025) Mapping the northernmost transnational non-native population of Xenopus laevis using pooled eDNA sampling. In: Anastácio P, Ribeiro F, Chainho P (Eds) Invasions in Aquatic Systems. NeoBiota 102: 227-248. https://doi.org/10.3897/neobiota.102.150311

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DOI: 10.3897/aca.9.e202345

Authors: Martin Hejda, Alessandra Kortz, Petr Pyšek, Jan Čuda, Josef Brůna, Ana Novoa, Jan Pergl, Pavel Pipek, Kateřina Štajerová, Irena Axmanová, Suneeta Bhatta, Israel Borokini, Franz Essl, Ingolf Kühn, Barbara Tokarska-Guzik, Mark van Kleunen, Marten Winter

Abstract: The character of invaded habitats provides a complex information about the ecology of naturalized aliens and suggests the type of processes associated with their establishment at a landscape level. While single-habitat affiliations are typically studied, the synergistic combinations of habitats occupied by species offer more detailed and complete information about plant naturalizations. We performedcluster analysis to reveal the similarity of 14 habitat categories, based on the composition of affiliated naturalized species;tested if the globally most represented habitat combinations occur more frequently than expected by random;tested if the species affiliated in a given combination of habitats are globally more successful, compared to species affiliated in the corresponding single habitats; andtested, if the frequency of the most represented habitat combinations differs between the Old World and New World and between the Northern and Southern hemisphere.Preliminary results of the cluster analysis revealed predictable groupings of invaded habitats similar in environmental conditions, such as Open forests – Scrub, Aquatic – Wetlands, Dryland – Rocky, Agricultural – Ruderal clusters. However, we found that Human-maintained grasslands and Natural grasslands are occupied by very different suites of naturalized alien species. Globally, the combinations of human-disturbed habitats containing either Ruderal or Agricultural habitat occurred with a significantly higher frequency than expected at random and occupied more regions than those restricted to either habitat alone. This suggests that habitat generalism – specifically across anthropogenic disturbance regimes – is a key predictor of global invasion success. Biogeographic patterns in the habitat combinations frequencies differ between the Old World and New World and between the Northern and Southern hemisphere. The most overrepresented habitat combinations in the Old World and Northern hemisphere were Open forests – Ruderal habitats and Agricultural habitats – Ruderal habitats, respectively, reflecting a legacy of prolonged human settlement and intensive landscape modification in regions where modern invasions originated. In contrast, the most overrepresented combination in the New World was Human-maintained grasslands – Ruderal habitats, a pattern likely driven by the historical expansion of European-style pastoralism and livestock management. Further, the most overrepresented combination in the South was Forests - Ruderal habitats, which may be linked to human-induced disturbances of (semi-) natural vegetation.

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DOI: 10.3897/aca.9.e202924

Authors: Tom Hill, Paul Stebbing

Abstract: The expansion and reconfiguration of water resource infrastructure within the United Kingdom, particularly through Raw Water Transfer (RWT) has resulted in increased connectivity of previously isolated aquatic systems. While crucial to enhancing resilience in national water supply, this increased connectivity may lead to a greater risk of invasive non-native species (INNS) spread. Despite RWT being recognised by the UK’s environmental regulator and the water industry as an important invasion pathway, risk assessment and risk analysis approaches remain fragmented. There is currently a need for a consistent framework for evaluating INNS risks associated with RWT schemes, and mechanisms for determining and monitoring the scale of biosecurity mitigation needed.The Strategic Resource Option Aquatic Invasive Non-Native Species Risk Assessment Tool (SAI-RAT) provides a structured approach to assessing the risk of INNS spread, establishment, and impact associated, primarily, with RWT, but also operational assets, and large-scale water resource schemes. The tool allows the technical parameters of the RWT to be incorporated, which influence organism survival and therefore risk. The tool builds on previous industry work and was developed by APEM ltd. on behalf of the UK’s Environmental regulator.By providing a consistent assessment structure, SAI-RAT supports more coherent and defensible prioritisation of INNS risks, improves comparability between schemes and enables better integration and performance monitoring of biosecurity options within long-term water resource options. Crucially, the developed approach moves beyond, while still integrating, species‑specific impact assessments to adopt a future‑proofed, system‑ and pathway‑focused framework that bridges ecological theory and operational decision‑making.This presentation outlines the conceptual rationale, scope, and theoretical underpinnings of INNS RWT risk assessment, illustrated through SAI-RAT, highlighting risk assessment's role in advancing integrated, scalable, and proportional approaches to managing aquatic biosecurity in increasingly managed and connected water resource systems.

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DOI: 10.3897/aca.9.e202891

Authors: Eugenia Nagodă, Mihaela Urziceanu, Paulina Anastasiu

Abstract: Sicyos angulatus L. (Cucurbitaceae) is an annual herbaceous vine native to North America. The plant colonizes semi-natural habitats (banks of inland waterways and water bodies, swamps, thickets, openings in floodplain forests, moist meadows in floodplain areas) and other artificial surfaces (wastelands).Currently, this taxon is reported in 21 European countries. In Romania, Sycios angulatus has been present since 1816, cited from Transylvania, later reported from other regions of the country such as Banat, Muntenia and Dobrogea.Our studies were conducted as part of the project POIM/178/4/1/120008 “Adequate management of invasive species in Romania, in accordance with EU Regulation 1143/2014 regarding the prevention and management of the introduction and spread of invasive alien species“. Thus, the study was carried out between 2020 and 2022 in the Romanian sector of the Danube River, on the left bank, and also in the Biosphere Reserve Danube Delta. The methodology adhered to the guidelines outlined by the project. Our data collection encompassed diverse natural and anthropogenic habitats, for each route traversed within these habitat types, we completed a field sheet that included data about geographical coordinates, population size of the species, phenology, habitat type, abundance-dominance and accompanying species. Regarding population size, a five-step scale was utilized, as follows: 1 (1-10 individuals); 2 (11-50 individuals); 3 (51-100 individuals); 4 (101-500 individuals); 5 (over 500 individuals).Sicyos angulatus has been recorded frequently in the study area, especially in the meadow forests, on sandy beaches, on concrete dikes and on household garbage. In the habitats invaded by Sicyos angulatus, we found the presence of both native (Populus alba, Rorippa sylvestris, Glycyrrhiza echinata, etc.) and alien plants (Ailanthus altissima, Amorpha fruticosa, Robinia pseudoacacia, Eclipta prostrata, Xanthium italicum, etc.). The size of the population was variable, from a few individuals, to over 500 individuals/100 sqm. Propagation is predominantly by seeds, but we also suspect the presence of vegetative propagation. Our study updates the data about Sicyos angulatus and offers a valuable tool for the managers involved in control and eradication of invasive alien species present along the Danube River.

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DOI: 10.3897/aca.9.e202329

Authors: Nina Šajna, Mirjana Šipek, Luka Petković, Dubravka Dujmović Purgar, Eva Vrecl

Abstract: Urban flora is represented by plants deliberately planted and by plants established by themselves. Opportunities for spontaneous establishment are scarce, especially for trees and other woody species and particularly if their establishment should begin from seeds What is more, urban plants can be of native or alien origin and successful spontaneous alien plants can represent a potentially invasive group of plants. We investigated the spontaneous occurrence of woody plants in urban green infrastructure of parks and urban hedges. We studied 15 urban parks in 3 European cities Ljubljana, Maribor (Slovenia), and Zagreb (Croatia) to detect possible spontaneous establishment. A total of 131 woody plant species were recorded, of which 59% were native. The highest species richness was found in the largest parks, however, park size explained only 18% of the variation in richness, whereas the variety of micro-locations had greater explanatory power. Notably, 14 invasive and 17 potentially invasive species were identified.We recognized urban hedges as a potential safe site for the establishment of woody plants outside parks. Urban hedges form urban green infrastructure, which can connect urban and peri-urban areas and in some landscapes even natural areas. In 100 urban hedges in Maribor we recorded 70 woody species from 29 families, with 63% being alien and 10% locally invasive, while 95% of the recorded alien species originated from ornamental plantings. Urban hedge characteristics significantly influenced the richness and composition of spontaneous woody plants, which further changed along the urban-rural gradient. Our results confirmed that urban parks can act as major sources of potential plant invasions, while the urban hedges can act as pathways for the spread of invasive alien woody species, underscoring the need for regular monitoring and timely management interventions.

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DOI: 10.3897/aca.9.e202845

Authors: Yukti Taneja, Ylva Lekberg, Robert Meagher, Phil Hahn, Christoph Rosche, Dávid U. Nagy, S. Luke Flory

Abstract: Plant invasion success emerges from simultaneous interactions with multiple biotic partners, yet invasion ecology has largely relied on isolated, pairwise hypotheses such as Enemy Release or Enhanced Mutualism. Enemies and mutualists often co-occur and generate non-additive effects where one interaction modifies the strength or direction of another. Such interaction modifications may produce plant performance outcomes that cannot be inferred from pairwise hypotheses.Arbuscular mycorrhizal (AM) fungi and herbivores exemplify this complexity. AM fungi can enhance nutrient uptake and growth, but they may also alter plant nutrient quality, induce defensive traits, or create carbon-allocation trade-offs that influence herbivore impacts. During invasion, species experience turnover in mutualists and enemies across biogeographic ranges, potentially reshaping cost-benefit dynamics among partners. Thus, AM fungi may modify herbivory differently in native versus non-native ranges, but whether these shifts contribute to invasion success remains unresolved.We asked whether AM fungi alter effects of herbivory, if these effects differ between native and non-native populations, and what mechanisms may underlie enhanced performance in the non-native range. We predicted that AM fungi would modify plant-herbivore interactions differently in the non-native range, where populations may better balance herbivore resistance and mutualistic benefits through allocation strategies, plasticity or pre-adaptation.We tested these predictions using Erigeron canadensis, fast-growing annual herb native to North America and invading much of Eurasia. Seeds were collected from 30 populations (15 native, 15 non-native) spanning broad latitudinal and climatic gradients. In a fully factorial greenhouse experiment, we manipulated AMF inoculation (MycoBloom) and generalist herbivore soyabean looper Chrysodeixis includens. After two months of mycorrhizal establishment, plants were treated with two herbivory bouts of one-week followed by a three-week recovery period.We found that AM-associated plants from the non-native range exhibited a ~50% reduction in the odds of leaf damage (OR=0.52), with damage declining from ~14% to ~7%, and insect survival decreasing from 66% to 36%. A significant range × treatment interaction indicates AMF-mediated increases in resistance in non-native populations, whereas AM fungi did not alter resistance in native populations. Ongoing analyses of resistance traits, nutrient chemistry, and belowground allocation will clarify underlying mechanisms.Together, these results provide some of the first experimental evidence that interactions among multiple biotic partners jointly shape invasion success and highlight the limitations of relying solely on pairwise hypotheses to predict invasion outcomes. Finally, we present a framework to incorporate non-additive effects among mutualists and enemies into invasion research.

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DOI: 10.3897/aca.9.e202838

Authors: Zoé Bescond--Michel, Giovanni Vimercati, Matheo Pallo-Robles, Selene Escobar-Rámirez, Manuel Mejía-Toro, Gonzalo Rivas-Torres, Pieter van `t Hof, Sven Bacher

Abstract: The human-mediated introduction of alien species across biogeographic barriers has resulted in multiple and diverse environmental and socio-economic impacts worldwide. While these impacts are often negative, such as biodiversity loss and livelihood harm, some alien species offer benefits for native species or people. This complexity highlights the need for standardized, evidence-based bidirectional impact assessments to inform conservation management and policy.To address this, we launched a four-year project in 2025 in which we conduct global-scale impact assessments across five different groups: ants, large mammalian herbivores, rodents, Rosaceae, and Verbenaceae. To do so, we are using the IUCN Environmental Impact Classification for Alien Taxa (EICAT), IUCN (2020), its complement EICAT+, Vimercati et al. (2022), for the positive environmental impacts, as well as their equivalents for socio-economic impacts SEICAT, Bacher et al. (2017), and SEICAT+.Additionally, we record both environmental and socio-economic impacts at the local scale, within the Galápagos Islands, specifically on San Cristóbal Island. Indeed, although recognized as a World Heritage Site, the Galápagos Islands are threatened by more than 1500 introduced species that impact the unique, mostly endemic biodiversity, as well as humans activities related to it.Fieldwork is currently underway to quantify environmental impacts of the invasive plant Lantana camara (Verbenaceae) on native vegetation and arthropod communities, across two seasons: the wet season (March-June 2026) and the dry season (October-December 2026). Field-based impact data will then be compared with global assessment data, exploring whether global patterns predict local outcomes, using Lantana camara as a case study. Preliminary results obtained from the first sampling season are presented here.We are also quantifying socio-economic impacts for six specific alien species in Galápagos: common lantana (Lantana camara), blackberry (Rubus niveus), green stink bug (Nezara viridula), rats (Rattus spp.), Spanish cedar (Cedrela odorata) and, tropical fire ant (Solenopsis geminata). These species were selected because they belong to the five groups examined in the global impact assessment and were also identified as locally relevant to Galápagos stakeholders through an expert‑based workshop conducted in 2022. Impact data will be collected by surveying key stakeholders, including conservation professionals, farmers, tourists and tourist guides.By investigating how impact magnitude, direction, and frequency vary by context and across different spatial scales, our project aims to advance understanding of the dynamics of alien species’ impacts on native biodiversity and people and to support local conservation efforts.

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DOI: 10.3897/aca.9.e202704

Authors: Nicolás Amigó Jürschik, Montserrat Vilà

Abstract: Many invasive plants are larger and produce more seeds in populations from the introduced range compared to those from their native range. Invasive plants might also benefit in their introduced range from early flowering, shorter life cycles and high resource acquisition. In annual plants from Mediterranean regions, these traits might be advantageous because plant growth is limited by drought. We compared plant performance (aboveground biomass and fecundity), phenology (time to flowering and lifespan) and leaf traits (SLA and N content) in six annual non-native plants from grassland populations in California and native populations in Spain. The study species were two grasses Avena barbata and Bromus hordeaceus, two legumes Medicago polymorpha and Trifolium angustifolium, and two forbs Silene gallica and Lysimachia arvensis). According to Cal-IPC A. barbata, B. hordeaceus and M. polymorpha are pests in California because they cause ecological and economic harm. We collected seeds from introduced and native populations across different climate conditions and grew them all under common outdoor conditions.We found that in some species, plants from seeds of the introduced range were larger, more fecund, had a shorter lifespan and larger SLA than from the native range. By contrast, in some other species the reverse or non-significant differences were found between ranges for several traits. Some trait variation could be explained by climate differences amongst populations, but this was mostly within the native range, suggesting that our study taxa are not yet locally adapted to climatic conditions of their introduced range. Overall, our common garden experiment indicated that the invasion success of these six annual grasses is not clearly associated with superior performance or fast plant life-history traits.

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DOI: 10.3897/aca.9.e202652

Authors: Letícia Brito, Heliana Teixeira, Ana Lillebø

Abstract: Wetland systems are key components of many coastal zone, playing a critical role in global ecological and economic sustainability. However, biological invasions represent a pervasive pressure in these environments, with significant impacts on biodiversity and socio-economic activities. Pontederia crassipes, one of the world’s worst invasive alien plant species, was introduced to Europe in the 18th century and continues to cause substantial ecological and economic impacts. As a freshwater macrophyte with limited tolerance to low salinity occurring in coastal lagoons, this species has been associated with multiple impacts across aquatic ecotones. Assessing the environmental effects of invasive species across coastal gradients requires integrated analytical frameworks. In this study, we apply the Drivers–Pressures–State–Impact–Response (DPSIR) framework to evaluate the impact of P. crassipes along a freshwater-estuarine continuum in a protected coastal lagoon in Portugal. We integrated existing seasonal environmental datasets with data from previously conducted in-situ and ex-situ experiments to assess biomass dynamics and ecosystem processes as decomposition and mineralisation associated with this invasive macrophyte. Our results indicate a salinity-driven functional shift, with P. crassipes acting as a nutrient sink in freshwater sectors and as a nutrient source in more saline environments, due to enhanced decomposition and mineralization processes. This shift alters ecosystem functioning and contributes to spatial variability in the potential ecosystem services and disservices provided by water hyacinth along the aquatic continuum. By combining process-based observations with a DPSIR framework, this study identifies key ecological mechanisms underlying invasion dynamics across salinity gradients and highlights critical limitations of current management strategies. These findings support the development of integrated, spatially explicit management approaches aimed at understanding the balance between the potential ecosystem services/disservices with the aim to mitigating the impacts of invasive macrophytes in transitional coastal systems.

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DOI: 10.3897/aca.9.e202630

Authors: Morelia Camacho-Cervantes

Abstract: Biological invasions are a major driver of biodiversity loss, with impacts emerging from individual interactions to ecosystem-level processes. Here, we synthesise findings from multiple published experimental and field studies on freshwater fishes in Mexico to evaluate how behavioural mechanisms influence invasion dynamics and their ecological consequences. Across laboratory behavioural experiments, mesocosm studies, and field surveys involving native and invasive poeciliid and goodeid fishes, we quantified behavioural traits including heterospecific sociability and behavioural plasticity, and assessed their effects on invasion success, native species persistence, and community structure. Experimental studies showed that invasive fishes consistently altered social behaviour, habitat use, and reproductive interactions of native species, including species involved in reintroduction programmes. Field-based community and functional diversity analyses further revealed reductions in functional richness and increasing biotic homogenisation in systems exposed to multiple invasions. Moreover, global change drivers, including climate warming and chemical pollution, amplify these effects by modifying behavioural responses and interaction outcomes. Our findings highlight that incorporating behavioural mechanisms into invasion ecology frameworks is essential to predict invasion trajectories and to design effective management and mitigation strategies.

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DOI: 10.3897/aca.9.e202131

Authors: Laís Carneiro

Abstract: Quantifying the ecological impacts of biological invasions on a standardized basis is essential to fully understand how severely they impact native species and ecosystems. The InvaPact database provides the most complete and up-to-date evidence data extracted from more than 10,000 peer-reviewed studies globally. In addition, this database includes the quantitative translation of the depicted impacts of each of these studies into a unified metric presented in the same session. This provides in total over 100,000 quantified impact events, each described with 76 variables, which allows to characterize each impact type, each invasive species, each invaded ecosystem alone and associated with various drivers. This study is the first global analysis of this massive database on quantitative ecological impacts. Here, we compare the global impacts of large taxonomic groups (micro-organisms, fungi, plants, invertebrates and vertebrates), highlighting the most impactful invasive species, both in terms of highest impacts and in terms of diversity of types of impacts. We analyzed impacts at several spacial scales (countries, continents, habitats and ecosystems), and show that they are not evenly impacted and reported, especially between ecological levels. Last, we quantified which mechanisms are the most associated with high impacts, and how impact values have been evolving with time. Together, these results provide a strong knowledge basis for fundamental and applied research, management and policy. This global analysis is intended to serve as concluding presentation to the session.

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DOI: 10.3897/aca.9.e202615

Authors: Arturo Cocco, Michelina Pusceddu, Erika Bazzato, Emanuele Sanna, Andrea Lentini, Alberto Satta, Ignazio Floris

Abstract: The introduction, establishment, and spread of invasive alien species (IAS) pose a major threat to global biodiversity. Human activities, environmental and climate change, and intensification of international trade and transport networks have accelerated biological invasions, which show no signs of saturation (Seebens 2017; Seebens 2018).Sardinia is a key biodiversity hotspot in the central Mediterranean, characterized by high levels of endemism and ecological heterogeneity, which increase ecosystem vulnerability to biological invasions (Fois et al. 2020;Bazzato et al. 2021). Its strategic location and intense traffic further enhance the risk of IAS introduction and establishment. In this context, cross-border cooperation is essential for prevention, early detection, and management. Within this framework, the INTERREG Italy–France Maritime Project ALIEM Vigil - Measures for Limiting, Managing, and Monitoring the Introduction of Invasive Alien Species in Mediterranean Transport Zones promotes coordinated actions across Mediterranean transport zones.Project activities included mapping and characterization of entry points; capitalization of methodologies developed in previous ALIEM projects; expansion of surveillance and early warning systems; stakeholder training and awareness; and testing of innovative control and eradication strategies. This contribution presents the main outcomes achieved by the Sardinian research unit.Key outcomes comprise modelling the potential distribution of Vespa crabro in Sardinia under current and future climate scenarios (Bazzato et al. 2025), and the development of a global dataset of Stator limbatus occurrence records (Cocco et al. 2022), integrated with ecological and biogeographic information on host plants. Furthermore, the surveillance network enabled the prompt detection and elimination of the first Vespa velutina nest in Sardinia. No new introductions of alien xylophagous pests were detected at monitored entry points, and Cydalima perspectalis was recorded at very low population densities in the only Italian natural population of Buxus balearica, with minimal associated damage.These results are shared with project partners across the cooperation area and highlight the importance of cross-border collaboration to improve integrated approaches for IAS management, building on the legacy of previous ALIEM initiatives.

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DOI: 10.3897/aca.9.e202421

Authors: Mariana Chiuffo, Agostina Torres, Mauro Tammone, Martin Nuñez, Mariano Rodriguez-Cabal

Abstract: Climate change is reshuffling the interactions that structure communities, with major implications for biological invasions. A key consequence of such reshuffling is the alteration of biotic resistance through changes in antagonistic interactions such as post-dispersal seed predation. This process is highly context dependent and influenced by factors such as climate and microhabitat. However, how large- and local-scale factors interact to shape seed predation remains poorly understood. In this study, we conducted a seed removal experiment along a precipitation gradient in Patagonia, Argentina, to evaluate whether a large-scale factor, precipitation, interacts with a local-scale factor, microhabitat type (open or closed vegetation), to influence seed predation patterns of a non-native conifer species (Pinus ponderosa). By measuring seed predation at 960 depots across 12 precipitation levels, we found that predation varies across environmental conditions. Seed predation changed along the precipitation gradient and tended to be higher in open habitats at lower precipitation and in closed habitats at higher precipitation, indicating a shift in granivore activity, although this pattern was contingent on temporal context. These findings suggest that the interaction between climatic conditions, local habitat structure, and temporal contexts jointly determines any potential contribution of seed predation to biotic resistance.

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DOI: 10.3897/aca.9.e202609

Authors: Francesco Boscutti, Francesco Liccari, Maurizia Sigura, Giovanni Bacaro, Giacomo Trotta

Abstract: Human-induced changes have profoundly transformed terrestrial ecosystems, creating novel habitats where biological invasions reshape plant communities and contribute to biodiversity loss. While landscape structure is widely recognized as a key factor in invasion dynamics, the role of landscape connectivity remains less explored.This study synthesizes evidence from vegetation-based analyses conducted in lowland anthropogenic landscapes of Friuli Venezia Giulia (north-eastern Italy), characterized by a mosaic of urban areas, agricultural systems, and residual natural and semi-natural habitats. By integrating metrics of landscape structure and ecological connectivity, we assess how processes operating across spatial scales influence alpha- and beta-diversity patterns of native and alien vascular plants.Our results highlight a strong scale dependence in invasion dynamics. At local scales, habitat conditions (i.e., soil properties, resource availability, and disturbance regimes) act as filters shaping early invasion stages. At broader scales, landscape composition, configuration, and connectivity regulate invasion success. Urban and agricultural matrices function both as sources of alien species and as corridors facilitating their spread.Peripheral and weakly connected patches support higher native species richness and compositional uniqueness, suggesting lower susceptibility to invasion. In contrast, central and highly connected patches are more prone to alien species dominance and biotic homogenization. These patterns vary among habitats, with wooded systems showing particularly strong responses to fragmentation and connectivity.Overall, our findings emphasize the need to consider both landscape structure and connectivity to better understand and manage alien plant invasions.

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DOI: 10.3897/aca.9.e202608

Authors: Zbigniew Celka, Marcin Nobis, Artur Pliszko, Katarzyna Bzdęga, Julian Chmiel, Zygmunt Dajdok, Władysław Danielewicz, Marcin Dyderski, Czesław Hołdyński, Alina Urbisz, Blanka Wiatrowska, Adam Zając, Barbara Tokarska-Guzik

Abstract: Over the last decade, the number of alien plant species in Poland increased from 921 species (Tokarska-Guzik et al. 2012) to 975 species (Jackowiak 2023). Our current study provides a comprehensive update to the checklist of alien vascular plants in Poland, synthesising data from numerous local and regional floristic and ecological studies conducted since 2012. We present the invasion status of new or overlooked non-native vascular plant taxa in the Polish flora, based on a critical review of the literature and herbarium materials, as well as field observations and unpublished data. We identified 191 new taxa (species, subspecies, varieties and nothospecies) compared to the 2012 list. After updating the list now includes over 1000 species. One third of added taxa we classified as casual aliens (ephemerophytes) (61) and over half of the group of added species - as naturalized anthropophytes (130). Among the naturalized ones, neophytes (kenophytes) (123) predominate although about 5% (7) are archaeophytes and hybrids that are most likely archaeophytes. Moreover, we found over 300 garden escapes (ergasiophygophytes) emerging outside cultivation, which indicates a further potential upward trend. Among the naturalized aliens we classified over 100 non-invasive and a dozen as potentially or regionally invasive. Weedy beets (spontaneous hybrids among Beta vulgaris subsp. vulgaris and B. vulgaris subsp. maritima, and B. macrocarpa) are considered as regionally invasive weeds. Cotula coronopifolia, Echinochloa muricata, E. oryzoides, and Phytolacca americana are recognized as regionally invasive species that threaten natural habitats. Most of the potentially invasive species spread regionally, except for Dittrichia graveolens, which is already found in many regions of Poland. Furthermore, we have added to the list 5 invasive alien species of European Union concern, of which only Lysichiton americanus has been already recorded as established in natural habitat (Bochynek et al. 2023), whereas Myriophyllum aquaticum, Pistia stratiotes, Pontederia crassipes, and Salvinia molesta are escapees from cultivation. So far, they are not naturalized in Poland. The high number of new additions in the flora of Poland reflects, on the one hand, the advanced level of floristic surveys in many regions of the country, and on the other, demonstrates the ease with which many alien ornamental plants escape from cultivation. Among the main drivers facilitating the spread of anthropophytes, apart from climate change, the most significant in the country are development of road infrastructure (including expressways), increasing urbanization, and progressive changes in land use.

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DOI: 10.3897/aca.9.e202594

Authors: Marija Kovačević, Suzana Buzjak, Igor Boršić, Brenda J. Grewell

Abstract: The aquatic species Ludwigia peploides (Kunth) P.H. Raven (family Onagraceae) is an invasive alien species of Union concern, i.e. included on “the Union list” since 2016 (European Commission 2016), according to the European Union Regulation No. 1143/2014 (European Union 2014). It is native to Americas, Australia and east Asia, with four subspecies recognized today (POWO 2026). In Europe, the species is associated with the formation of dense stands in slow-flowing and stagnant freshwater habitats, where it can alter habitat structure, reduce native biodiversity and affect water quality (Di Lernia et al. 2025). Its invasion success is largely driven by high ecological plasticity and multiple reproductive strategies.The species was recorded in Croatia eight years ago (Buzjak and Sedlar 2018), yet its distribution and infraspecific identity remain insufficiently resolved. In 2025, several new populations were discovered that are morphologically different from the one first reported. One recently discovered population was analysed in detail and can be unambiguously assigned to Ludwigia peploides subsp. montevidensis (Spreng.) P.H.Raven (Fig. 1. This determination is based on a consistent set of morphological characters.In contrast, at the first reported Croatian locality, population was re-sampled and re-examined in the field and subsequently in the laboratory. This population shows morphology predominantly like L. peploides subsp. glabrescens (Kuntze) P.H.Raven, particularly capsule length (up to ~40 mm) and number of seeds per locule (15–17), both of which correspond to diagnostic traits in existing identification keys. However, it also exhibits a mixture of characters, including sparse indumentum on upper stem portions and occasional pubescence on fruits and tepals (Fig. 1). Herbarium specimens deposited in the herbaria ZA and ZAGR, representing previously published records identified only at species level, show similar glabrescens-like morphology.This combination of traits suggests that key diagnostic characters traditionally used to delimit subspecies within L. peploides may not be fully stable. The incongruent morphological pattern may reflect either a higher degree of infraspecific plasticity than previously recognized, or a partial overlap of diagnostic traits among subspecies.

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DOI: 10.3897/aca.9.e202597

Authors: Marc Ventura, Rocco Tiberti, Quim Pou-Rovira, Aaron Pérez-Haase, Teresa Buchaca

Abstract: In alpine biogeographic regions, aquatic and semi-aquatic habitats are important biodiversity reservoirs and habitats for species of community interest, but they are often threatened by multiple factors. The conservation state of protected habitats and species in the EU is expected to worsen as long as no actions or conservation strategies are implemented. LIFE RESQUE ALPYR aims to restore mountain aquatic habitats by improving the conservation of several target habitats/species in four Nature 2000 sites from the alpine biogeographical regions of the Pyrenees (in northeastern Iberian Peninsula) and the Alps (in northwestern Italy). The target habitats include eleven aquatic and semi-aquatic habitats, of which five are prioritary: high mountain lakes (HCIs 3110 and 3130), alpine and subalpine grasslands, heaths and meadows (HCIs 4020*, 6230*, 6410, and 6520), mires (HCIs 7110*, 7140, 7230, and 91D0*) and petrifying springs (HCI 7220*). The target species include native amphibians found either in both areas (Rana temporaria) or solely in the Pyrenees (Euproctus asper and Alytes obstetricans); the semi-aquatic mammal Galemys pyrenaicus living in Pyrenean streams and lakes; and seven insectivorous bats, including Barbastella barbastellus, Myotis myotis, and Plecotus macrobullaris, which are present in the Pyrenees and the Alps, and Rhinolophus hipposideros, Myotis blythii, Myotis bachsteinii, and Nyctalus lasiopterus from the Pyrenees. The target habitats and most of the target species have naturally fragmented distributions, occurring in small areas of the European alpine biogeographic zone, and are affected by anthropogenic pressures. The introduction of trout or minnows in most alpine lakes caused the disappearance of native amphibians and invertebrates at local and landscape scales, indirectly affecting aquatic mammals and terrestrial species, such as bats, that rely on aquatic insects for feeding. Minnows can also cause the strong eutrophication of lakes, leading to drastic habitat degradation. The affected habitats and species are HCIs 3110 and 3130, R. temporaria, E. asper, A. obstetricans, G. pyrenaicus, R. hipposideros, P. macrobullaris, B. barbastellus, M. myotis, M. blythii, M. bachsteinii, and N. lasiopterus. The proposed actions and methods with regard to fish species involve the experimental eradication of non-native fish in high mountain lakes by means of both chemical (rotenone) and mechanical methods (traps, nets, and electrofishing). The project will provide data regarding replicable and exportable conservation actions and will increase awareness of pertinent conservation issues among stakeholders and the public. In addition, the project will promote the transfer of its background data and results to conservation authorities concerned with other European high mountain areas.

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DOI: 10.3897/aca.9.e202592

Authors: Etienne Branquart, Christine Bodmer, Nicolas Brasero, Marie Chariot, François Colard, Dido Gosse, Jérémie Guyon

Abstract: Crassula helmsii, Hydrocotyle ranunculoides, Lagarosiphon major, Ludwigia grandiflora, L. peploides, Myriophyllum aquaticum and M. heterophyllum are among the invasive alien aquatic plants (IAAPs) most frequently recorded in ponds and lakes in Wallonia (southern Belgium). All are invasive alien species of Union concern under Regulation (EU) No 1143/2014. Current invasion pressure remains limited: fewer than 100 invaded sites per species have been recorded regionally, and the invaded surface area is <1,000 m² in 80% of field cases. Repeated manual removal (hand pulling) is often prioritized by field managers because it is simple to implement and generally the least disruptive option for ecosystem services (De Baene 2022). However, field trials indicate that some populations cannot be eradicated by manual removal even after several years of effort, and that effectiveness varies with species, invasion extent and site characteristics (Branquart et al. 2024).To support management decision‑making, we developed a feasibility index referring to the expected success rate of manual removal actions targeting a clearly delineated IAP population scored on a 5-point scale (= management effectiveness sensu Booy 2017). It combines IAAP identity, invaded area and the number of local constraints recorded from the field before starting to remove plants. IAAPs were classified into four categories according to their resilience to management, based on field managers’ experience and the scientific literature. Management resilience was found to be lowest for Hydrocotyle ranunculoides and highest for Crassula helmsii, for which only 10% of published studies reported successful eradication (van der Loop et al. 2018). Invaded area was assessed in summer, when the target plants reach their maximum extent. Finally, eight key constraints to manual eradication were identified through a survey of field managers (e.g. rooting depth, bank morphology, sediment thickness, intermixing with native helophytes, and co‑occurrence of Crassula helmsii).Eradication outcomes from the LIFE RIPARIAS project were positively associated with the feasibility index determined prior to management initiation. Applying the index across invaded waterbodies in Wallonia suggests that approximately 70% of sites can be managed effectively through manual removal, whereas the remaining sites (mostly invaded by Crassula helmsii and Ludwigia spp.) likely require alternative control methods (tarping, mechanical removal or biological control) or containment measures.

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DOI: 10.3897/aca.9.e202578

Authors: Jason Sckrabulis, Andrew Nisip, Henry Smith, Margaret Simon, Flávia Rogério, Claire Godineau, Philip Harmon, Maria Orive, Robert Holt, Erica Goss, Nicole Gauthier, Natalie Christian, Keith Clay, S. Luke Flory

Abstract: Pathogen spillover between host species is a major driver of pathogen emergence in humans, animals, crops, and natural ecosystems. Many human pathogens reflect spillover from wild animal hosts to humans; forest pathogens have spilled over from ornamental plants; and novel crop pathogens have emerged via spillover from wild hosts. However, the mechanisms and eco-evolutionary dynamics of spillover, especially among plant hosts, are poorly understood. Invasive species might exacerbate spillover events because they provide physical linkages across ecosystems boundaries; they disrupt natural areas, and they establish within disturbed ecosystems. We hypothesize that invasive plants, with dense populations at ecosystem boundaries, facilitate the eco-evolutionary dynamics of pathogen transmission between ecosystems. To examine this possibility, we focused on a natural-agricultural ecosystem boundary with a recent emergence of a novel fungal pathogen of industrial hemp. The fungus Bipolaris gigantea has caused widespread epidemics on the invasive grass Microstegium vimineum in eastern US forests for over 20 years. After legalization of hemp cultivation in 2014, there were massive outbreaks of the same pathogen on hemp in the same region as diseased M. vimineum. Utilizing this system, we aimed to quantify the ecological drivers of pathogen transmission between ecosystems. To identify ecological components of disease severity and transmission to hemp, we conducted: field surveys to quantify the occurrence and severity of disease on experimental sentinel hemp plants placed in transects at multiple distances from Microstegium stands, anda field experiment manipulating invasion, moisture (i.e., irrigation), nutrition (i.e., fertilizer), and endophyte inoculation. In both circumstances, we found that the severity of disease on hemp was best predicted by significant interactions between hemp biomass and Microstegium disease severity. In the field experiment, we also found that disease severity on hemp was predicted by a significant interaction between fertilizer addition and endophyte inoculation. Fertilizer increased hemp disease severity intuitively through increased hemp growth; however, endophyte inoculation reduced disease severity but only in the presence of fertilizer. This effect was not driven by interactive effects of fertilizer and endophyte inoculation on hemp size. Together, these results provide substantial support for cross-boundary transmission of a pathogen mediated by an invasive species. These data are also poised to validate future theoretical dynamical and eco-evolutionary models by our group.

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DOI: 10.3897/aca.9.e202033

Authors: Frederique Steen, Wietse Chanet, Berdien De Beer, Peter Desmet, Teun Everts, David Halfmaerten, Bieke Maex, Stien Mertens, Damiano Oldoni, Lenin Riascos, Kevin Scheers, Margot Vermeylen, Rein Brys, Tim Adriaens

Abstract: Invasive crayfish are an increasing concern in European freshwater bodies, but surveillance relies often on opportunistic records and therefore remains fragmented. In Flanders, the Craywatch citizen science project was developed to address this gap by applying a standardized trapping protocol across a broad spatial scale, hence generating a baseline for invasive crayfish occurrence. In parallel, a multiplex eDNA ddPCR approach was developed to enable sensitive simultaneous detection of multiple crayfish species from water samples. Together, these initiatives illustrate how complementary monitoring tools could be combined into a more strategic surveillance framework. Craywatch demonstrated the value of citizen science for broad spatial coverage, rapid data collection and early warning, while eDNA offers added value for detecting species at low densities. This contribution reflects on the transition from ad hoc observations to standardized surveillance, and on how broad-scale volunteer-based sampling, targeted professional follow-up and molecular detection can be aligned in function of introduction risk, invasion stage and management. Using the Flemish case as an example, we discuss how monitoring could evolve from ad hoc monitoring towards citizen science and ultimately an integrated and adaptive invasive crayfish surveillance in Flanders.

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DOI: 10.3897/aca.9.e202572

Authors: Lucinda Lintott, Hannah Tidbury, Paul Stebbing

Abstract: The introduction and spread of Non‑Native Species (NNS) are driven by human activities. In the marine environment, pathways such as recreational boating, commercial shipping, water sport and aquaculture facilitate the movement of organisms across biogeographical boundaries. Biosecurity constitutes the initial and most effective stage of NNS management, targeting human‑mediated pathways to reduce the risk of NNS introduction and spread. Recognising and addressing the human dimension of NNS introduction and spread is critical to achieving sustainable biosecurity outcomes.Effective biosecurity depends on uptake by key stakeholders, alongside the development or enhancement of appropriate regulatory, strategic, and technical frameworks. However, punitive or onerous plans, measures and policies, especially if introduced without stakeholder consultation, are likely to have limited support, hindering effective and sustainable implementation. Early and meaningful stakeholder engagement is therefore essential, and requires careful consideration of human awareness, risk perception, and behaviours that influence compliance and practice. Despite its recognised importance, approaches to stakeholder engagement within biosecurity planning are often inconsistent and poorly standardised, varying widely between sectors, locations, and projects. This lack of a structured or systematic engagement process can limit representativeness, reduce trust, and undermine the long‑term uptake and effectiveness of biosecurity measures.Through the delivery of multiple marine biosecurity plans at differing spatial scales and in varied social contexts, an approach to stakeholder engagement that supports biosecurity uptake has been developed, comprising five steps. The first step is systematic stakeholder mapping, which includes input from the entity(s) commissioning the biosecurity plan and local contacts, and takes account of the pathways present within the spatial scope of the plan. Next, keystone liaisons are identified. These are individuals or groups with wide-reaching local contacts who can facilitate communications between local groups, businesses, recreational clubs, regulators and the wider public. Contact is then made with the identified stakeholders, carefully considering the source, method, frequency, content, and aims to engage recipients while avoiding messaging fatigue. The next key step is the delivery of online and in-person workshops and events, making use of engaging presentations, demonstrations (e.g., specimens) and interactive feedback sessions. The workshops invite representatives from all sectors to participate together and learn about NNS and biosecurity (accounting for the range of pre-existing knowledge that stakeholders may have) as well as providing a platform through which their feedback and valuable local knowledge can be heard. There are multiple benefits of mixing stakeholder groups, including providing reassurances that “blame” is not being directed at them or their sector; rather, all sectors and marine users have a responsibility to undertake biosecurity. Finally, stakeholders are invited and encouraged to feedback into the developing plan to ensure that they feel the actions within it are relevant, appropriate and achievable. This is incorporated into the finalised marine biosecurity plan, which is accompanied by an implementation plan outlining a recommended approach to continuing engagement by key identified parties.In summary, targeted engagement, including mixed‑sector workshops, can foster a shared understanding of cumulative risk, reduce perceptions of blame, and reinforce that while activities differ in risk and regulatory oversight, core biosecurity principles apply across sectors. By promoting community‑based, multi‑sector collaboration, risk awareness can be enhanced, behaviour change supported, and voluntary uptake of biosecurity measures increased.

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DOI: 10.3897/aca.9.e202121

Authors: Katharina Dehnen-Schmutz, Helen Bayliss, Alex Franklin, Laura Abraham, Heidi Blom, Soria Delva, Carla Gavrilescu, Louise Hendrickx, Miia Jauni, Eva Malta-Pinto, Daniyar Memedemin, Anna Poimala, Cristina Preda, Laurentiu Rozylowicz, Cândida G. Vale, Joana Vicente

Abstract: Involving stakeholders in the management of invasive alien species has long been known to be essential for successful outcomes. This process starts with the development of tools and methods where stakeholders can play a crucial role to improve their efficacy through iterative feedback loops as well as testing their usefulness. Living labs provide the space and collaboration where this can happen by bringing together researchers, local authorities, businesses, citizens and conservation organisations involved in invasive alien species management in the Living Lab area. In the OneSTOP project a network of five Living Labs has been established across Europe (Belgium, Finland, Portugal, Romania, United Kingdom) to provide the experimental space for testing emerging technologies in real live settings. The Living Lab communities work with scientists in the project to test computer vision camera technologies for the automatic detection of invasive plants and insects and air eDNA sampler technologies. Based on their local knowledge suitable sites and species are selected in the Living Lab areas, and they can then use the equipment in hands on experiences. Living Lab communities are also involved in the project by suggesting species relevant for them to be included in surveys exploring people’s perceptions of invasive alien species and for project tasks modelling potential distributions of species of concern. Other activities include citizen science focused on gardens as early warning system for emerging invasive ornamental plants and invertebrates.All species record data collected through these activities feed into the project’s data pipelines (i.e., to GBIF) and contribute to OneSTOP’s automated alert systems that notify relevant stakeholders, such as local conservation managers, about emerging invasive species threats. In follow-on activities, Living Lab communities will also test these alert systems and develop scenarios for potential responses.

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DOI: 10.3897/aca.9.e202560

Authors: Maria Loreto Castillo, Ana Novoa, Pavel Pipek, Ivan Jarić, Alessandra Kortz, Rubén Rabaneda-Bueno, Reut Vardi, Josef Brůna, Petr Pyšek

Abstract: Human influence is a key driver of plant invasions. Yet, invasion science has largely focused on ecological factors, often overlooking the human and social dimensions that shape the invasion process. The InvaSyn project aims to address this gap by identifying plant invasion syndromes that integrate these dimensions, ultimately improving our understanding of the context-dependent nature of biological invasions.To contribute to this aim, we draw on the Protected Areas and Invasive Alien Species (PROTIAS) database, developed within the SynHab project (www.synhab.com), which compiles data on the presence of naturalised alien plant species across nearly 1,500 protected areas (PAs) in more than 50 countries, encompassing approximately 5,000 alien taxa. Using novel culturomics approaches, we aim to characterise people's interest in and awareness of non-native plant species listed in the PROTIAS database by analysing Google Health Trends and Wikipedia.For this, we searched en.wikipedia articles associated with PROTIAS-listed PAs for content related to these non-native plant species. For each species, we quantified relative search volumes on Google Health Trends and pageviews on en.wikipedia. Furthermore, in each Wikipedia PA articles we examined the frequency of mentions, the context in which species appeared (e.g. introduction, impacts, management), and the level of engagement generated (e.g. the number of visits to species links). We then used these metrics to classify non-native species into groups with similar patterns of people’s interest and awareness (e.g. high engagement but limited search volume) using multidimensional scaling (MDS). Species-level analyses were also conducted to relate these metrics to naturalisation success, defined as the number of PROTIAS-listed PAs and GloNAF (Global Naturalised Alien Flora) regions from which a species has been reported. We hypothesise that certain types of plant invasions in PAs are shaped by distinct combinations of social and ecological factors that group into identifiable clusters (e.g. a species that attracts high public attention due to its substantial impact but has limited naturalisation success). Additionally, we recorded the frequency of mentions of other major drivers of global environmental change (e.g. pollution, fire, direct exploitation of species) in the Wikipedia PA articles, to contextualise how people's interest in plant invasions compares with attention to other conservation-related threats. By integrating the PROTIAS database with culturomics, this study aims to generate insights on the perception of plant invasions in PAs that can help guide conservation efforts.

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DOI: 10.3897/aca.9.e202099

Authors: James Hardwick, Zarah Pattison, Christopher Hackney

Abstract: Global introductions of invasive non-native plant species are accelerating, particularly within riparian habitats. A sediment equilibrium exists between native riparian vegetation and riverbank stability in riparian habitats, with the forces that drive and resist riverbank sediment erosion remaining broadly balanced. The establishment and spread of invasive non-native plant species that outcompete and replace native riparian vegetation can alter the phenological and physical trait composition of riparian plant communities, disrupting this riverbank sediment erosion equilibrium. Despite growing recognition of invasive non-native plants having the potential to modify the physical structure of riparian habitats, quantifying the scale of this disruption remains understudied, with sediment yield offering a measurable proxy for river geomorphic change driven by plant invasions. Here, we aim to investigate how invasive non-native plants influence river geomorphic change at the reach scale, where a reach is defined as a discrete channel section of uniform hydrological characteristics, using Impatiens glandulifera as a case study invader. A series of modelling experiments were undertaken using a modified version of the landscape evolution model (CAESAR-Lisflood), incorporating vegetation – river feedbacks. Our results reveal a strongly non-linear sediment yield response, characterised by several critical plant cover thresholds. At low invasion levels, sediment yield remains low, indicating a lag between I. glandulifera establishment and measurable impact. However, once a critical threshold is exceeded, sediment yield and riverbank erosion increase rapidly as the stabilising influence of native vegetation declines. At high invasion levels, sediment yield approaches a new quasi-stable state reflecting near-total floodplain cover. The spatial pattern of erosion also shifts from localised hotspots to more homogenised reach wide changes with increasing I. glandulifera cover. We demonstrate that invasive plant cover has a marked effect on reach-scale geomorphic stability and identify several critical cover thresholds providing key evidence for the importance in prioritising early management interventions in invaded riparian corridors.

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DOI: 10.3897/aca.9.e201559

Authors: Tamara Kovács, Agnes Zolyomi, Katharina Dehnen-Schmutz, Helen Bayliss, Alex Franklin, Miia Jauni, Anna Poimala, Heidi Blom, Cristina Preda, Carla Gavrilescu, Laurentiu Rozylowicz, Ana Novoa, Sofie Meeus, Simon Reynaert, Laura Abraham, Quentin Groom, Tim Adriaens, Joana Vicente, Cândida G. Vale, Eva Malta-Pinto

Abstract: Public perceptions of invasive alien species are critical for the societal acceptance of management measures. However, there is limited comparative cross-country evidence regarding the combined influence of awareness, values, emotions, and communication framings on these perceptions.This study, conducted within the EU Horizon Europe project OneSTOP, presents findings from representative surveys of the general public (aged 18+) in Belgium, Finland, Portugal, Romania, and the United Kingdom (~500 respondents per country). Each country survey follows a shared structure but features two locally relevant invasive alien species—one plant and one animal—selected based on EU Union list status, public visibility, perceived charisma, and management controversy. To examine the influence of communication on attitudes, the survey included an embedded framing experiment: respondents were randomly assigned to one of three information treatments—a control providing general invasive alien species information, and two treatments presenting the same species framed through different justifications for management, such as biodiversity impact, environmental or cultural loss, economic cost, human health risks and social norm.Based on approximately 2,500 responses, we expect to provide insights into how awareness and knowledge influence public perceptions of invasive alien species across the five countries, and how these perceptions are further shaped by emotional responses associated with species charisma, perceived ecological and economic impacts, cultural significance, personal experience, and proximity. The findings are anticipated to show how these factors, together with socio-economic characteristics, influence public attitudes toward different management options, including support for eradication, control, or tolerance. The analysis aims to offer evidence on whether and how different framings shift attitudes toward management options, and which types of arguments most effectively increase support for action across countries and socio-demographic groups. The results will inform the development of targeted communication and citizen engagement strategies within and beyond the OneSTOP project.

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DOI: 10.3897/aca.9.e202561

Authors: Riccardo Scalera, Angeliki Martinou, Quentin Groom, Jodey Peyton, Louise Hendrickx, Helen Roy

Abstract: The emergence of infectious diseases (EIDs) represents one of the most significant yet under-researched threats to global biodiversity and environmental security. While international assessments recognize invasive alien species (IAS) as primary drivers of ecosystem change, the specific role of "alien pathogens"—those introduced to new ranges or spread by invasive vectors—remains a critical blind spot in both science and policy. Current regulatory frameworks effectively address pathogens with direct economic impacts on livestock or agriculture, yet those affecting wildlife and native ecosystems frequently fall between the cracks of fragmented institutional mandates. To address this systemic gap, we propose the establishment of the WildHealth network, an innovative transdisciplinary framework designed to embed biological invasions robustly within the One Health approach.The core innovation of this proposal lies in the creation of a unified, multi-sectoral platform that does not currently exist. By bridging the divide between invasion biology and disease ecology, the WildHealth network aims to foster a community of expertise encompassing invasion biologists, plant pathologists, and ecologists alongside veterinarians, epidemiologists, and public health professionals. Critically, the network intends to integrate mathematical modellers, social scientists, and humanities experts to address the socioeconomic drivers of disease spread and improve the science-policy interface. This collaborative structure is designed to unite researchers with governmental agencies, NGOs, and stakeholders from the agriculture, forestry, and fisheries sectors.To ensure scientific depth and provide actionable outcomes, the proposed network focuses on Forest and Island Ecosystems as primary case studies. Forests serve as "sentinels" for terrestrial health, where alien pathogens threaten carbon sequestration, timber resources, and complex biodiversity networks. Conversely, islands act as living laboratories; their high endemism and geographic isolation make them disproportionately vulnerable to EIDs, offering a controlled context to map host-pathogen dynamics and test the efficacy of novel biosecurity protocols. By grounding the network’s efforts in these specific environments, the framework moves beyond theoretical goals to develop tangible management tools, such as early-detection toolkits for foresters and specialized biosecurity measures for island conservationists.A primary function of the WildHealth network will be the mobilization and harmonization of baseline information. Currently, data on alien pathogens is scattered across disparate repositories and lacks standardized terminology. The network seeks to lead the transition toward FAIR (Findable, Accessible, Interoperable, and Reusable) data standards, creating a foundation for predictive models that assess host specificity and ecosystem susceptibility. By identifying specific introduction pathways and fostering a geographically balanced exchange of knowledge, this network provides the coordination necessary to safeguard global biodiversity and enhance the resilience of our most vulnerable natural heritage.The complexity of pathogen invasions requires a response that no single discipline or nation can provide in isolation. As we move toward formalizing this initiative, there is a clear opportunity for the diverse expertise present at this conference to help shape the network's trajectory. We welcome a dialogue with researchers, policy-makers, and practitioners interested in contributing to this transdisciplinary vision. By aligning our collective efforts, we can ensure that the WildHealth network achieves the critical mass necessary to transform wildlife health surveillance and build a more resilient, integrated future for global environmental health.

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DOI: 10.3897/aca.9.e202110

Authors: Riccardo Scalera, Miguel Angel Carretero, Chloe Adamopoulou, Tim Adriaens, Per-Arne Ahlen, Emanuele Berrilli, Fabrizio Calò, Teresa Catelani, Francesco Ficetola, Sam Fisher, Jim Foster, Benedetta Gambioli, Mirko Guasconi, Hubert Laufer, Marta López-Darias, Krzysztof Kolenda, Jairo Mendoza-Roldan, Elba Montes, Gianpaolo Montinaro, Priscilla Nesi, Domenico Otranto, Claudio Pardo, Cecilia Roscetti, Daniele Salvi, Giulia Simbula, Katerina Sioumpoura, Wojciech Solarz, Mitsuhiko Toda, Matthijs P. van den Burg, Leonardo Vignoli

Abstract: Invasive alien lizards are among the most frequently introduced reptiles worldwide, yet their management remains fragmented, underreported, and comparatively overlooked in invasion science. Here, we present the first global, practitioner-informed synthesis focused specifically on the management of invasive lizards, integrating evidence from the scientific literature with the outcomes of an international workshop held in 2025 that brought together 42 experts from 10 countries involved in detection, control, health surveillance, policy, and biosecurity.Our review shows that introductions are driven primarily by the pet trade and unintentional transport pathways, while impacts extend far beyond simple establishment success. Invasive lizards can disrupt native communities through predation, competition, behavioural interference, hybridisation, and pathogen transmission, with consequences for biodiversity, ecosystem functioning, public health, agriculture, and infrastructure. Management responses are highly context-dependent, but a consistent pattern emerges globally: prevention and early detection and rapid response (EDRR) are far more effective than reactive intervention once populations are established.A key original contribution of this synthesis is the identification of recurrent barriers that cut across taxa and regions. These include low detectability, high reproductive potential, taxonomic and biogeographic uncertainty, limited availability of species-specific control tools, chronic underfunding, inconsistent reporting of management outcomes, and major socio-political constraints such as public resistance, stakeholder conflict, and legislative misalignment. The review also highlights a substantial implementation gap between scientific knowledge and management practice, with many projects remaining undocumented or poorly evaluated.By combining global case studies with on-the-ground management experience, this review provides a rare “from practice to synthesis” perspective. We argue that effective invasive lizard management requires a shift towards proactive prevention, stronger governance and pathway regulation, improved knowledge circulation, and closer integration of ecological, health, and socio-economic dimensions within adaptive management frameworks.

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DOI: 10.3897/aca.9.e202559

Authors: Berit Michler, Frank-Uwe Michler

Abstract: The North American raccoon (Procyon lotor) has become one of the most widespread non-native carnivores in Europe, with Germany representing the core of its European range. Its ecological flexibility, omnivorous diet, and pronounced adaptability to human-modified landscapes have enabled raccoons to colonize a wide range of habitats, including forests, agricultural landscapes, and increasingly urban environments (Fischer et al. 2024). This expansion has triggered ongoing debates about appropriate management strategies, particularly regarding the effectiveness and objectives of hunting as the primary control measure.In Germany, raccoon management is largely based on sustained hunting pressure. Annual harvest numbers have increased continuously over recent decades and now reach several hundred thousand individuals per year. Despite these high hunting bags, raccoon populations continue to expand in both distribution and local density (Fischer et al. 2015). This apparent discrepancy raises important questions about the effectiveness of hunting as a population control tool for a highly adaptable and reproductive species. Ecological characteristics such as flexible habitat use, high reproductive potential and compensatory population responses can limit the long-term effectiveness of hunting-based control efforts (Beltrán-Beck et al. 2011). Consequently, increasing hunting intensity alone may not necessarily lead to population reductions at larger spatial scales.At the same time, raccoons are frequently perceived as a major threat to native biodiversity, particularly through potential predation on birds, amphibians and other small vertebrates. However, empirical evidence for substantial population-level impacts remains limited (Michler et al. 2023). Although documented risks to human health in Europe remain comparatively low, concerns about zoonotic disease transmission have received considerable attention, too (Stope 2023).These uncertainties complicate the formulation of clear management objectives. While hunting is widely promoted as the central management instrument, its practical outcomes often remain poorly evaluated. Moreover, raccoon populations have become increasingly established in urban and suburban environments, where hunting is often restricted or impractical, further limiting the effectiveness of this approach as a stand-alone management strategy. Given these limitations, raccoon management in Germany may benefit from a more differentiated and evidence-based approach. Instead of focusing exclusively on broad population reduction through hunting, management efforts could place greater emphasis on targeted conservation measures for particularly vulnerable species and habitats.The case of the raccoon illustrates the broader challenges associated with managing established non-native wildlife species. Effective management will likely require adaptive strategies that combine scientific evidence, targeted conservation measures and realistic expectations regarding the achievable outcomes of hunting-based population control.

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DOI: 10.3897/aca.9.e202558

Authors: Franck Courchamp, Corey Bradshaw, Daniel Pincheira-Donoso, Gabriel Henrique de Oliveira Caetano, Ross Cuthbert, Sonia Tieo, Shengyu Wang, Chunlong Liu, Ugo Arbieu, Arman Pili, Andrea Desiderato, Steven Cooke, Jonathan Tonkin, Josie South, Josh Firth, Tad Dallas, Laís Carneiro

Abstract: Despite ongoing efforts to categorize the diverse ecological impacts of biological invasions, ecology lacks a standardized metric to translate these heterogeneous and context-dependent observations into a shared quantitative scale. Here, we introduce InvaPact, a metric that rigorously integrates the normative importance of impact types with their empirical severity into a unified numerical currency, bounded between 0 and 100. InvaPact enables robust comparisons across diverse taxonomic, geographic, and ecological contexts, by bridging structured qualitative classifications and rigorous quantitative synthesis. This unifying tool has the potential to catalyze macroecological syntheses. It allows researchers to aggregate isolated datasets, test foundational ecological hypotheses, and forecast temporal impact trajectories. In doing so, InvaPact provides the standardized translation of the scientific evidence base required to prioritize global conservation interventions, assess ecosystem damage, and help to guide international biosecurity policies under global change. This presentation will serve as an introduction of the session, that will contain several presentations of analyses of impacts of invasions at the macro-ecological scale.

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DOI: 10.3897/aca.9.e202547

Authors: Michaela Medzihorská, Jaroslav Cepl

Abstract: Biological invasions are a major component of global change and can substantially affect native biodiversity, community composition, and ecosystem functioning. Yet invasion success often appears inconsistent with expectations from population genetics. Introduced populations are commonly founded by relatively few individuals and are therefore expected to experience bottlenecks, reduced genetic diversity, inbreeding, and lower adaptive potential. Nevertheless, many invasive populations establish, expand, and adapt rapidly in novel environments, a contradiction known as the genetic paradox of invasions.Hybridization may help resolve this paradox by increasing genetic variation, reducing inbreeding depression, and generating novel trait combinations. However, it may also impose costs by disrupting coadapted gene complexes, generating Dobzhansky–Muller incompatibilities, or reducing local adaptation. Whether hybridization promotes or constrains invasion success is therefore likely to depend on ecological conditions and the genetic architecture of fitness-related traits, including dominance and epistasis.To investigate these processes, we developed a spatially explicit, individual-based simulation model of contact between a local and a non-native population. Implemented in R using AlphaSimR, the model simulated dispersal, mating, reproduction, and selection across a 20 × 20 landscape. It incorporated additive effects, dominance, and additive-by-additive epistasis, allowing both genetic incompatibilities and advantageous hybrid combinations to emerge.We evaluated 144 scenarios varying in epistatic effects, assortative mating, parental divergence after burn-in selection, and environmental structure. Scenarios were simulated under homogeneous conditions and across a spatial environmental gradient. For each scenario, we quantified invasion spread, hybridization, fitness, genetic and genic variance, and FST.Across scenarios, assortative mating strongly influenced invasion and hybridization outcomes. When assortative mating was absent, extensive hybridization occurred, and invasive genotypes were often lost, whereas the local population persisted most frequently under mixed mating conditions with both assortative and random mating. Population outcomes also depended on epistatic architecture. Scenarios based on Bateson–Dobzhansky–Muller incompatibilities generally favored the persistence of local and invasive populations over hybrids, while hybrids were most successful when novel advantageous epistatic interactions emerged in hybrid genotypes. Burn-in duration further shaped outcomes: local populations persisted mainly after short burn-in phases, when parental divergence was low, whereas invasive and hybrid populations were more successful after longer burn-in phases.Overall, our results show that hybridization can either facilitate or constrain invasion success depending on mating structure, parental divergence, environmental heterogeneity, and the genetic architecture of fitness. By linking dispersal, mating system, local adaptation, and multilocus genetic mechanisms, our modeling framework provides a mechanistic basis for understanding when hybridization promotes demographic or genetic rescue and when it instead limits invasion through incompatibilities, mating barriers, or reduced hybrid fitness. More broadly, this approach highlights the value of integrating explicit population-genetic mechanisms into invasion research and helps predict the evolutionary consequences of contact between local and non-native populations.

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DOI: 10.3897/aca.9.e202541

Authors: Akanksha Ingale, Aino Kalske, Timo Vuorisalo, Satu Ramula

Abstract: Invasive alien species (IAS) are one of the major drivers of global biodiversity loss. When introduced into new environments, these species often outcompete native organisms, disrupt ecosystem functioning, and cause significant ecological and economic damage. IAS are associated with an estimated global annual cost of 423 billion USD, including both their impacts and management efforts.Stakeholder perceptions of IAS management are influenced by a range of underlying socio-economic factors. Identifying which of these factors have been examined is important for the development of more effective management strategies. Differences in values and perceptions among stakeholder groups can result in varying expectations and responses to IAS management; however, the socio-economic drivers of these differences have been studied inconsistently. In this study, the aim is to identify and map the socio-economic factors that have been investigated in relation to stakeholder perceptions of IAS.We conducted a literature review of peer-reviewed articles indexed in Scopus, focusing on socio-economic variables commonly examined in IAS perception studies worldwide. Our findings indicate that relatively few studies on public perceptions of IAS were published prior to 2010, and a clear geographical bias exists, with the majority of research (58%) conducted in Europe and North America. The literature also showed a greater focus on plants than on animals. The most frequently examined socio-economic variables were age, gender, and education, which often also explained perceptions of IAS, whereas factors such as ethnicity and household size were less commonly considered. The number of socio-economic variables examined per study decreased over time, but there was no relationship between publication year and the type of analysis used, with about 57% of the studies relying on quantitative rather than descriptive analysis.

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DOI: 10.3897/aca.9.e202537

Authors: Mariëlle van Riel, Muriel Thirion

Abstract: Invasive alien species (IAS) pose an increasing threat to biodiversity and ecosystem functionality, demanding a shift toward integrated management across different phases of the invasion curve. Traditional management approaches focus on eradication or continuous population control, which are often costly and unsustainable once an invader becomes widespread. To overcome these challenges, the LIFE RESILIAS project introduces an ecosystem-oriented approach that prioritizes strengthening ecosystem resilience over symptom management. By restoring abiotic and biotic conditions and actively introducing native competitors, the Ecosystem Resilience Approach (ERA) aims to lower the carrying capacity of an ecosystem for invaders to facilitate establishing self-regulating processes. However, managing biological invasions efficiently requires addressing multiple stages of the invasion continuum. While LIFE RESILIAS focuses on systems where species have already established and degraded natural buffering capacities, LIFE RIPARIAS optimizes the initial phases of the curve through Early Detection and Rapid Response and highly coordinated cross-border stakeholder engagement. At a joint workshop conducted during the InterLIFE Benelux 2025 meeting, the two projects explored how these frameworks can mutually reinforce one another to create a more comprehensive IAS management strategy. Integrating RIPARIAS’s rapid detection workflows can safeguard resilient ecosystems from new introductions. Conversely, applying RESILIAS's resilience-building techniques in these peripheral areas reduces empty ecological niches, decreasing the overall likelihood of recolonization and development of invaders. By bridging early-stage eradication protocols with long-term ecosystem restoration, the combined insights from RIPARIAS and RESILIAS offer a replicable, dual-layered workflow. This joint perspective demonstrates that effective invasive species management is not merely about suppressing individual target species, but about fundamentally working on early detection, rapid action, and facilitating the ecosystem’s self-regulating processes to decrease its vulnerability to invasions.

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DOI: 10.3897/aca.9.e202536

Authors: Naiara Suárez-Rodríguez, Borja Maestresalas, Marta López-Darias

Abstract: Invasive species represent one of the most critical threats to island biodiversity due to their predatory and competitive pressure, with particularly severe impacts on endemic species. In Gran Canaria (Canary Islands, Spain), the California kingsnake (Lampropeltis californiae), a colubrid species native to the USA and Mexico, has been established as an invasive species since the early 2000s, leading to documented declines of up to 90% in endemic reptile populations, affecting endemic reptiles’ physical conditions and generating trophic cascades. In its native range, this species feeds primarily on mammals and other snakes, and secondarily on lizards and birds. Although predation on passerines has been confirmed through stomach content analyses in the invaded range in Gran Canaria, its community-level impacts remain poorly understood. In this context, this study aims to quantify the predation impact and pressure exerted by L. californiae on passerine birds. A comparative field survey was conducted during the breeding season 2026 in 40 invaded and 40 non-invaded sites across three areas of the island (northwest, northeast and east). Sampling sites, defined as "invaded" and "non-invaded" based on cumulative snake capture data from 2009 to 2025, consisted in 50-m radius semicircular point-counts in which a 10-min census was performed each month between April-July. We hypothesize that invaded areas will show a significant decrease in richness and abundance of ground-nesting and shrub-dwelling species. Preliminary field observations indicated negative relationships between snake presence and passerine abundance and richness, highlighting the impact this invasion is having on the island ecosystems. This research provides essential understanding of the impacts of invasive species, thereby informing management on priorities to mitigate their impacts and preventing irreversible biodiversity loss.

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DOI: 10.3897/aca.9.e202530

Authors: Kateřina Štajerová, Lukáš Sekerka, Petr Šmilauer, Dana Blumenthal, Ragan Callaway, Peter Kotanen, Urs Schaffner, Petr Pyšek

Abstract: The remarkable success of many invasive non-native species is thought to be due in part to “enemy release”, the hypothesis that introduced species escape their natural enemies, and thus increase in abundance and impact. Evidence for enemy release is mixed, perhaps in part because most non-native vs. native comparisons do not clearly account for plant phylogeny, density, the nativity, different plant organs and life stages or diet preference of herbivores. Here, we tested enemy release with a community approach, in which herbivory was compared between confamilial or congeneric invasive non-native and native species that were all highly abundant, or dominant, in North American grasslands. We found that invasive dominant plants were attacked much less frequently by herbivores than co-occurring native dominants, and this difference was more pronounced for leaves than flowers. Flowering and non-flowering native plants suffered more damage than invasive plants in either stage. Non-native specialist herbivores (many of them introduced as biocontrol agents) and generalist herbivores of unknown origin were more common on invasive species, and in contrast, native specialists preferentially attacked native plant species. Our results support the enemy release hypothesis, but the magnitude of herbivore damage is highly context-dependent and related to feeding guild and origin of both herbivores and plant species.

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