Franck Courchamp

Biological invasions impose substantial ecological and socio-economic burdens, yet the global economic impacts of invasive plants remain incompletely quantified. Here, we provide the first comprehensive global synthesis of reported monetary costs associated with invasive plants using the InvaCost database. After data validation and filtering for highly reliable, observed estimates, we identified a total of US$361.8 billion in documented costs between 1960 and 2022, representing a conservative baseline of invasive plant impacts at global level. Costs were unevenly distributed across taxa and regions, with a small number of species and families accounting for the vast majority of costs, and with North America accounting for 61% of reported impacts. Terrestrial environments and the agricultural sector bore the greatest economic burden. The cost of damage was over three times the amount spent on management; preventive investments were negligible. Annual costs increased markedly from the 1990s onward, exceeding US$50 billion in some years. Cumulative annual damage costs followed a sigmoidal trajectory, indicating rapid escalation over recent decades and suggesting substantial future economic pressures if historical cost-accumulation patterns continue. Socio-economic context and size of countries were key predictors of reported costs, highlighting strong reporting and capacity biases. Despite the magnitude of documented impacts, plant invasion costs remain severely underestimated due to taxonomic, geographic and sectoral data gaps. Our synthesis reveals the scale, distribution and increasing burden of invasive plant costs globally, underscoring the urgent need for improved reporting, proactive prevention and more effective management to limit future economic losses

In response to escalating environmental pressures, many sectors have turned to sustainability-focused solutions, but these can backfire when ecological complexity is overlooked. Insect farming has recently emerged as a promising alternative to mitigate environmental challenges, yet it carries the risk of facilitating biological invasions, one of the most severe threats to global biodiversity. In this piece, we apply key concepts and hypotheses from invasion biology to the context of insect farming to better understand and anticipate this risk. We also highlight the crucial importance of biosecurity and outline practical measures to minimize the likelihood of invasive events. This perspective is particularly urgent for policymakers and international organizations aiming to advance sustainable food systems while preventing further biodiversity loss.

Invasive species pose a major threat to biodiversity and ecosystem functioning. Although it is widely recognized that invasion impacts differ across habitats and taxonomic groups, a systematic evaluation of their perceived ecological importance has remained unexplored. We surveyed over 400 international experts in invasion science to systematically assess the importance of the 19 different types of ecological impacts across habitats, taxa, and levels of biological organization. We found consistent patterns in expert perceptions, where changes in assemblage structure, population size, and species loss were rated as most important, while others, like soundscape, fire regime, and microclimate, consistently received lower scores. Scores between taxa varied more than scores between habitats, while responses were more consistent among respondents with greater experience in the field. Our results highlight the impact types that would require greater management efforts (i.e., the higher scores), as well as those that could benefit from further research (i.e., the lower scores).

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.

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.

Human-mediated redistribution of organisms has reshaped global ecosystems, leading to the increasing homogenization of biotic communities. Among invasive taxa, vertebrates, including mammals, birds, reptiles, amphibians, and fishes,are recognised as among the most harmful groups due to their high establishment rates and strong top-down pressures. Despite their known consequences, a systematic global synthesis explicitly linking these impacts to specific mechanisms across all vertebrate classes has been lacking. We addressed this gap by leveraging InvaPact v1.0, a global database containing over 99,000 impact records extracted via fine-tuned large language models. Ecological impacts were quantified using an expanded Environmental Impact Classification for Alien Taxa (EICAT) framework, which assigns impact scores based on the severity and level of biological organisation affected. We analysed the spatial and temporal distribution of these impacts, compared vertebrate impacts to those of invertebrates, and assessed taxonomic representativeness. Our analysis reveals that ecological harm is concentrated within a limited subset of taxa. The most impactful species identified include wild boars ( Sus scrofa ), domestic cats ( Felis catus ), rabbits ( Oryctolagus cuniculus ), and black rats ( Rattus rattus ). Predation emerged as the dominant mechanism of impact, particularly for Mammalia and Actinopterygii, primarily driving declines in native population sizes and changes in assemblage structure. Spatially, the highest impact magnitudes were recorded in Australia and the United States, with significantly higher impacts observed in island ecosystems compared to mainland ecosystems. Furthermore, we found that vertebrates generally have a greater impact across all habitat types than invertebrates. These findings highlight that invasive vertebrate impacts are uneven across taxa and space, often driven by a few high-impact "worst" invaders. The high vulnerability of island biota to predation-mediated extinctions underscores the need for prioritised management and eradication programs in these regions. Additionally, our representativeness analysis suggests research biases toward charismatic or well-known invaders, such as mammals, which may influence global reporting patterns.

Ecological and economic impacts of invasive species are now well-documented through established frameworks, and both their understanding and reporting is increasing. These tools improve classifications and assessments, data collection and interoperability, as well as communication, collaboration, and decision-making. However, despite growing evidence that environmental and human health are deeply interlinked and that biological invasions represent a growing global threat for public health, with invasive species at the core of the One Health triad, no comprehensive scheme currently exists to characterise the health impacts of invasive species and their underlying mechanisms. growing evidence that environmental and human health are deeply interlinked and that biological invasions represent a growing global threat for public health, with invasive species at the core of the One Health triad, no comprehensive scheme currently exists to characterise the health impacts of invasive species and their underlying mechanisms. This results in major gaps in knowledge, data integration and collaboration between invasion science and public health fields. We developed a comprehensive, standardised typology/conceptual framework to classify mechanisms through which invasive species negatively impact human health, as well as discussing resulting impacts. We developed a preliminary classification based on a narrative literature review and refined it using an iterative expert-review process in discussions among the author team during two dedicated workshops and a two-round Delphi survey gathering feedback from invasion science and public health experts, collecting a total of 72 responses over the two rounds. discussions among the author team during two dedicated workshops and a two-round Delphi survey gathering feedback from invasion science and public health experts, collecting a total of 72 responses over the two rounds. Invasive species can negatively affect all dimensions of human health (i.e. physical health, mental health and social health) through various, complex, direct and indirect mechanisms. We identified 10 broad mechanisms by which invasive species can negatively affect human health, covering the full diversity and complexity of health threats represented by biological invasions: disease transmission, exposure to allergens, toxins, injuries or the disruption of ecosystem services and the side-effects of control methods. We described resulting impacts on all dimensions of human health and developed an ordinal metric to scale their magnitude. This provides a more consolidated understanding of the health impacts of biological invasions and a standard tool for interdisciplinary researchers and practitioners to identify, assess and scale them. The framework also represents a basis for developing global databases including more effective risk assessments, management interventions, and decision-making.

Biological invasions negatively impact biodiversity and ecosystem functions worldwide. Understanding the spatiotemporal dynamics of these impacts is crucial for improving management actions, yet how their impacts scale through space and time remains poorly resolved. Here, we reviewed effects of invasive ants and assess how they vary across ecological and geographical context and invasion histories from 577 studies, using a global meta-analysis. We found that invasive ants caused substantial changes in native species behaviour and abundance, community structure and ecosystem functions. We detected overall greater negative effects on species at higher levels of ecological complexity, with lasting negative effects on the invaded ecosystems for more than 60 years. Invasive ants caused rapid and persistent negative effects at lower levels of ecological complexity (e.g., individual or population), while at higher levels (e.g., ecosystem) they manifested with a time lag of approximately 30 years. Finally, our results show that ~ 61% of total studies are focused only on two species, indicating a publication bias and an important knowledge gap. This meta-analysis is the first to reveal that negative impacts caused by invasive species accumulate with increasing ecological complexity, these effects persist over one century and may accumulate on higher ecological levels over time.

Biological invasions impose substantial ecological and socio-economic burdens, yet the global economic impacts of invasive plants remain incompletely quantified. Here, we provide the first comprehensive global synthesis of reported monetary costs associated with invasive plants using the InvaCost database. After data validation and filtering for highly reliable, observed estimates, we identified a total cost of US$ 361.8 billion in documented costs worldwide between 1960 and 2022, representing a conservative baseline of invasive plant impacts at global level. Costs were strongly uneven across taxa and regions, with a small number of species and families accounting for the vast majority of costs and North America dominating reported expenditures. Terrestrial environments and the agricultural sector bore the greatest economic burden, while damage costs exceeded more than three times those related to management, and preventive investments remained negligible. Annual costs increased markedly from the 1990s onward, reaching peak values exceeding US$ 50 billion in some years. Cumulative damage costs followed sigmoidal trajectories, indicating rapid escalation over recent decades and suggesting substantial long-term economic liabilities under business-as-usual conditions. Socio-economic context and country size were key predictors of reported costs, highlighting strong reporting and capacity biases. Despite the magnitude of documented impacts, plant invasion costs remain severely underestimated due to taxonomic, geographic and sectoral data gaps. Our synthesis reveals the scale, concentration and accelerating trajectory of invasive plant costs globally, underscoring the urgent need for improved reporting, proactive prevention and more effective management to limit future economic losses.