Among terrestrial ecosystems, forests are the most heavily impacted by invasive species. Globalization continues to accelerate new introductions, while climate-driven shifts in temperature and disturbance regimes facilitate their spread. While most management and policy efforts emphasize preventing primary introductions, secondary spread—post-border movement within a region—is a critical yet underdeveloped area in the forest pest literature. Previous work on invasion pathways has clarified mechanisms of initial arrival, but terminology and treatment of secondary spread remain inconsistent. To address this gap, I conducted a systematic synthesis of invasive forest arthropod literature by developing an LLM-assisted, schema-guided data extraction pipeline implemented via Claude API (Anthropic) to process the full text of 2,706 peer-reviewed publications. This was used to evaluate how often and how clearly secondary spread is distinguished from primary introductions, what terms are used for these processes, and which mechanisms (e.g., human-mediated movement, natural dispersal) are documented as drivers of secondary spread. The number of invasive forest arthropod publications focusing on secondary spread has increased an average of 7.5% per year from 1977 to 2025. Only 2.82% of these papers use the term “secondary spread.” The most common alternatives include “within-region spread”, “spread”, and “post-establishment spread.” I further examine how ecological factors including feeding guild, host specificity, habitat type, and land use shape the rate and spatial pattern of spread across geographic regions. These findings highlight a significant gap in research on the secondary spread of forest pests. Ultimately, this synthesis provides conceptual and terminological clarity applicable across taxa and regions, supporting the development of more effective and targeted post-border surveillance and management strategies for invasive forest pests.

Invasive alien species (IAS) are a major driver of global biodiversity loss, generating substantial ecological, economic and social impacts. Prevention and early intervention are widely recognised as being more cost‑effective than long‑term management. As a result, IAS policy frameworks increasingly rely on predictive strategies and tools to guide prioritisation. Horizon scanning has emerged as a key approach, providing structured, forward‑looking assessments of IAS that are likely to arrive in a new area in the near future, establish invasive populations and cause harm. Despite widespread uptake of the method, there has, to our knowledge, been no global synthesis of how IAS horizon scanning exercises are conducted, how methodologies are developed, and what their potential policy implications are. Here, we present a global review of over 50 IAS horizon scanning exercises undertaken up to 2026, drawing on published and grey literature. We examine how horizon scans were designed across multiple taxonomic groups, geographic scales, regions and environments, evaluate their underlying objectives, such as informing policy and biosecurity, and review their recommendations. Our review shows that the number of horizon scans has been steadily increasing in recent years. Across the horizon scanning literature, terrestrial and freshwater environments were more frequently represented than marine systems, and exercises more often covered a range of taxonomic groups (including plants and animals) rather than focusing on a single group (e.g. invertebrates) alone. Furthermore, the majority of horizon scanning exercises to date have been undertaken in Europe, predominantly at a country level, although transnational- and regional‑level exercises have also been conducted. Impacts on native biodiversity were the dominant focus, although consideration of economic and human health impacts have been increasing in recent studies. Horizon scanning outputs are most often intended to inform biosecurity planning and policy implementation, including the prioritisation of species for further risk assessment and risk management. Most exercises follow a broadly consistent workflow: compilation of large species longlists; application of exclusion criteria to focus further effort and review; structured scoring of likelihood of arrival, establishment, spread and impact; and the application of consensus‑based prioritisation through expert elicitation and moderated group discussions. However, we identified variation in how species lists are compiled/generated, how climate or habitat suitability is assessed, which risk‑scoring frameworks are applied, and whether management feasibility or socio‑economic considerations are formally incorporated. Many studies report uncertainty associated with scoring the likelihood of arrival, establishment, and impact, particularly for understudied taxonomic groups and emerging pathways. Recurring challenges include inconsistent reporting of methods and assumptions, and limited evaluation of whether identified species inform regulatory or other action. We highlight the value of horizon scans for the effective prevention of IAS and discuss how greater standardisation of reporting and systematic evaluation could strengthen the policy impact, e.g. by facilitating the transfer of outcomes between ecologically similar regions and allowing for the upscaling of local results to larger geographic scales. Similarly, as horizon scanning practice expands, this might allow the integration of big data analytics and machine learning methods to identify emerging patterns, pathways, and taxonomic or functional trends associated with invasion risk. This could facilitate more data-driven, automated and rapid screening processes, improving the scalability and consistency of assessments, and strengthening proactive decision-making.

In response to substantial losses in crop production, Florida producers have been seeking alternative species for cultivation. Pongamia (Millettia pinnata / Pongamia pinnata), a fast-growing, subtropical, leguminous tree native to southern Asia, Australia, and the western Pacific islands, has emerged as a potential substitute after a historical period as a landscape ornamental in the region. However, due to its toxicity, prolific production, and ability to disperse long distances along bodies of freshwater, pongamia is considered an environmental weed and was assessed as high invasion risk for Florida in 2016. To examine the establishment status in anticipated escaped populations in south Florida, we surveyed 15 sites with reported occurrences and found established populations at five sites. Among the established populations, we observed clear evidence of rapid spread along the St. Lucie and Cocohatchee rivers, with over 300 recorded individuals of varying sizes and ages across these two sites. These results strongly indicate that pongamia is established in southern Florida and spreading rapidly along freshwater channels. Furthermore, we suspect that poorly managed landscapes such as abandoned nurseries and private horticultural properties have facilitated the observed spread of pongamia. Therefore, we stress the importance of proper management to prevent seed escape from production areas, especially those near bodies of water. Additionally, we highlight the need for expanded surveillance and management for pongamia in Florida.

The pathways through which non-native species are introduced and spread help shape the rate and geographic patterns of biological invasions. These pathways can be classified as primary, where non-native species cross jurisdictional or biogeographic boundaries, or secondary, where species move within these boundaries after introduction. Despite fundamental economic, political, social, and ecological differences between these pathway types that affect the risk of species introductions and the prioritization of management responses, most classification schemes and regulatory frameworks do not explicitly distinguish between them. This lack of distinction is consequential: primary pathways are relatively well-defined and subject to biosecurity regulation, while secondary pathways remain poorly characterized and largely overlooked in policy and practice. Secondary pathways create multiple nodes from which non-native species spread, transporting individuals extensively and complicating containment efforts. Here we refine the distinction between primary and secondary pathways and explore their explicit separation in classification and management frameworks. We highlight how failing to recognize this distinction can limit the effectiveness of biosecurity systems, particularly by leaving secondary pathways inadequately addressed. Explicitly distinguishing these pathway types can help to improve invasive species control responses, strengthen cross-scale coordination efforts, reduce economic damage, and achieve global biodiversity goals.

1. Understanding the flowering phenology of invasive alien plants is essential for predicting their potential impacts on invaded ecosystems and developing effective management strategies. However, achieving this for globally widespread invasive species poses significant challenges. Digital data offer an efficient and scalable solution to studying the flowering phenology of plants across diverse regions and environments. 2. Here, we apply this approach to taxa in the genus Carpobrotus, one of the most problematic groups of invasive plants in coastal areas worldwide. We collected geotagged photographs from widely used online platforms (i.e. Instagram, Google Maps, and iNaturalist) at key tourist sites in six countries spanning native (South Africa) and non-native (Argentina, New Zealand, Portugal, Spain and the United States) regions. These records were analysed to document the flowering phenology of Carpobrotus plants in different regions linked to their genetic lineages (clusters), focussing on the start, end and peak flowering periods. 3. Our results show that broad floristic region and sampling locality, rather than genetic lineage, are the primary determinants of flowering phenology in the Carpobrotus taxa studied. Non-native populations often displayed extended flowering periods compared to native populations, potentially enhancing their pollen availability and seed production, contributing thus to increased propagule pressure or seed bank. Apparent differences among genetic clusters in single-model analyses were not retained once a site-level random effect was included, indicating that observed cluster contrasts reflect local environmental and sampling variation more than intrinsic genetic differences. 4. Practical implication. This study highlights the use of digital data to address critical knowledge gaps in the flowering phenology of invasive plants across native and non-native ranges. By identifying extended flowering periods and their potential contribution to increased propagule pressure through prolonged seed production and subsequent accumulation in the soil seed bank, our findings provide valuable insights for developing targeted management strategies, such as optimizing intervention timing to coincide with flowering peaks.

The Kunming-Montreal Global Biodiversity Framework (GBF) sets out ambitious global targets to reduce biodiversity loss by 2030 and will determine the conservation agenda for the next decade. Invasive alien species are a major driver of biodiversity loss in terrestrial and marine ecosystems; and a key focus of the GBF is therefore to reduce their introduction by 50% through pathway management as well as eradicating or controlling established alien species in priority sites (Target 6). Protected areas are among the most important priority sites for the management of biological invasions. However, delivery of Target 6 for protected areas entails coordination with other GBF targets especially in relation to rapidly evolving pathways such as increasing international and domestic tourism (Target 15), progressive encroachment of urban areas (Target 12), development of intensive agriculture/aquaculture systems in buffer zones (Target 10), species rafting on marine plastic (Target 7), and growing risk from range-shifting species under climate change (Target 8). The management of established invasive alien species requires effective spatial planning (Target 1) to prioritise the limited human and financial resources available to manage biological invasions including recognising those protected areas facing the greatest immediate and future threat, identifying the species that pose the greatest risk to threatened species (Target 4) and/or Nature’s Contributions to People (Target 11), and obtaining the necessary finance required to effectively control priority species (Target 19). The goal of expanding protected areas to cover 30% of land, water, and seas (Target 3) will need to avoid the inclusion of areas already harbouring invasive alien species. Addressing biological invasions must be an inclusive process (Target 22) undertaken over multiple years that involves the sharing of knowledge and data (Target 21). Decision-makers, protected area managers, researchers, and representative of local communities should all be involved in the regular prioritisation, implementation, and review of management activities. Consequently, the effective management of biological invasions to halt biodiversity loss by 2030 will not be realised by having an exclusive focus on achieving Target 6; it will also require that substantial progress is made with most GBF Targets. Elucidating the interconnectedness of different GBF Targets in relation to their direct or indirect role in the effective management of biological invasions reveals opportunities for a more integrated approach to biodiversity conservation. The inclusion of the multiple GBF targets in strategies to address invasive alien species is the step change needed to reduce the magnitude of this threat to biodiversity by 2030.

The United States imports thousands of live vertebrate species annually as part of legal trade. Escapes and releases from captivity are major pathways of invasion, however, the risk posed by the thousands of imported vertebrate species has not been systematically assessed. We conducted a horizon scan that used a data-driven climate match to filter a list of nearly 15,000 taxa drawn from across the globe of imported fish, amphibians, reptiles, birds, and mammals for rapid assessment by taxonomic experts. Experts evaluated 840 species and identified 32 (22 reptiles and 10 fishes) as having the highest risk for establishment, spread, and negative impacts. Of those high-risk species, the majority have the capacity to disrupt ecosystem processes via their role as top predators or the unique ecological niches that they occupy, while several of the snake species pose a threat to human health. High-risk species were often scored with high confidence while in contrast, low scores were attributed to a combination of ecological redundancy, low propagule pressure, or low climate match while low confidence arose from a lack of information in the literature (i.e., data deficiency). Our study therefore highlights legally imported species likely to cause the greatest harm with the recognition that many other species could also become invasive in the United States. The ranked list of vertebrate threats can be used to prioritize watchlists and inform the development of targeted regulations for importation can be applied to regions to provide a rapid, preliminary screening for large pools of potential invaders.

In recent decades, substantial evidence has accumulated regarding the effects of climate change on the establishment, spread, and impact of invasive species. While the importance of incorporating climate change into invasive species management and policy is increasingly recognized, practitioner experiences and perspectives are often overlooked. Consequently, invasive species research may be misaligned with the needs of managers and the threats of climate change. Here, we compare survey responses from a boundary-spanning organization, the Regional Invasive Species and Climate Change (RISCC) Management Network, to identify common priorities and challenges in managing invasive species in a changing climate in the United States. Survey respondents reported that 22% of management and research time is dedicated to emerging invasive species threats. Common barriers to climate-informed invasive species management include limited time, funding, and personnel. Understanding how climate change may impact control strategies was consistently identified as a high priority for invasive species management, followed by identifying resilient ecosystems and range-shifting taxa. These results demonstrate the critical need for stronger researcher-practitioner networks and greater investment in research and policy topics that more closely align with management needs to address the interacting stressors of invasive species and climate change.

. Public awareness is critical for societal support for conservation efforts, including management of biological invasions. However, traditional methods for assessing public awareness are limited, and its role as a key factor in alien species invasions remains largely unknown. The rise of participatory web and social media platforms, such as Twitter (rebranded as X), has provided opportunities to gain insight into societal perceptions through user-generated content. In this study, we assessed public discourse about invasive species on social media by analyzing over 500,000 tweets containing the term "invasive species" posted between 2006 and 2021. Our aim was to identify the most frequently mentioned taxa and habitats, prevailing topics, and subject matters that generated high engagement in discussions on biological invasions. We found that mammals, specifically domesticated and urban pests, were the most frequently mentioned, while aquatic habitats and those interfacing with aquatic habitats dominated the top 15 mentioned habitat types. Additionally, the use of location-based hashtags, such as the Great Lakes and Florida, suggests that people tend to be more engaged with invasive species issues in specific areas. We also observed that a relatively small subset of users contributed a disproportionately large share of retweeted content, highlighting the influence of a few key accounts. This study shows the potential of digital data for identifying prominent taxa, habitats, regions, and influential voices in invasive species discussions. Such information can help refine communication strategies, tailor policy interventions, and foster more effective public engagement in efforts to manage and mitigate the impacts of biological invasions.

The Kunming-Montreal Global Biodiversity Framework 2030 calls for the conservation of 30

Invasive alien plants (IAPs) are a frequent consequence of global connectivity and present significant threats to biodiversity, amplifying impacts from global climate change and habitat loss. Integrated management efforts for landscape-level plant invasions often include some combination of mechanical, cultural, chemical, and biological control. The former three have well established protocols and development pipelines for rapid responses to new invasions. Biological control of IAPs, however, is often employed only after the invaded region has reached some arbitrary but intolerable level of negative impact that triggers efforts to develop agents to provide control. Despite mounting evidence that investments in prevention and proactive approaches to IAPs are the most cost effective, most expenditures, including those for biological control development, continue to be in the post-invasion reactive phase. We build a rationale for earlier investigation and implementation of biological control for IAPs. A potential framework for this approach would pair prioritization methods (e.g., risk assessments and horizon scanning) to identify targets with extensive literature searches for known herbivores or foreign range surveys and early host range tests. In addition, resource sharing among regions and nations with similar climates and risks would alleviate the onus of investment from any one party. Finally, investments into conservation and training opportunities between nations further incentivizes maintaining natural resources for potential biological control. By developing and implementing biological control earlier in or before the invasion process, countless impacts and costs are lessened.

Risk assessment is an important tool in invasive species prevention and management, providing a structured approach to identify and evaluate the risks posed by non-native species. Despite the widespread development of risk assessment and risk analysis (collectively referred to as RA here) methods, there is a lack of information on which methods are used in practice. We conducted a global survey of RA practitioners from diverse regional, professional, and taxonomic contexts to identify the tools and databases used, the qualifications and experience of assessors, and the implementation and accessibility of RA results. 107 responses were received from practitioners focussed on all continents except Antarctica, with the most from the United States and the United Kingdom. Respondents reported using more than 46 different RA tools, with the Fish Invasiveness Screening Kit and the USDA Plant Protection and Quarantine Weed Risk Assessment the most commonly mentioned tools, based on the number of users. Plants were the most frequently assessed taxonomic group and terrestrial species, though representation from all taxonomic groups and systems exist. Respondents listed 107 generally open-access databases that they frequently use to conduct RAs, with the most commonly used sources being the CABI Invasive Species Compendium, occurrence records from the Global Biodiversity Information Facility (GBIF), and taxonomic information from the Integrated Taxonomic Information System (ITIS). Assessors typically had tertiary education, with the majority holding at least a master’s degree, though many did not believe that a post-graduate degree was necessary to be an effective assessor. After RAs were completed, assessments were predominantly reported to government agencies. Most finalized RAs included some measure of certainty and were usually publicly accessible, though few included a formal process for stakeholders to comment. Almost all respondents identified the importance of training and certification programs to standardize qualifications for assessors. Based on the views expressed in the surveys we discuss the importance of: (1) training and capacity building, (2) open access databases and FAIR (Findable, Accessible, Interoperable and Reusable) data standards, (3) incorporating stakeholders in the process, and (4) standardisation of tools; if these measures are implemented, they may enhance the consistency, transparency, and effectiveness of RAs of non-native species.

Climate change is expected to influence the frequency and severity of biological invasions in a variety of ways, including creating novel introduction pathways, decreasing the resilience of native habitats, inducing range shifts and expansions, and altering phenologies. As such, it is important to gain a better understanding of how invasive species managers incorporate climate change in their management strategies and identify the invasive species that are expected to pose the greatest threat under climate change. To address these questions, the Regional Invasive Species and Climate Change Management Network surveyed invasive species researchers and managers across four regions of the continental U.S. (the Northeast, Southeast, North Central, and Northwest) to determine the invasive species of greatest concern. This analysis will identify and compare the invasive species most frequently reported by researchers and managers for each region and describe their ecologies.

The rapid diversification of terminology associated with invasion ecology is a known barrier to effective communication and management. These challenges are magnified by the addition of terms and concepts related to climate-induced range-shifting taxa and/or changes to impacts. Further, institutional policies and terminologies for invasive species introduce new ambiguities when considering climate change. To alleviate communication and application challenges, we introduce a conceptual framework that organizes climate-related invasion terms, revealing ambiguities and gaps. Additionally, we illustrate how these ambiguities can affect management with four case studies and consider situations where resolution can improve policy and management outcomes. The framework can help users avoid inconsistent use of terminology, and prioritize when to address management and policy consequences related to associated terminological ambiguity.