The world is witnessing a global rise in numbers of emerging invasive alien species, but identifying which species pose a pandemic threat remains poorly understood. The disjointed international regulatory environment presents a significant challenge to biosecurity interventions at a global scale. A novel way forward is through One Biosecurity, an interdisciplinary approach to biosecurity policy and research that enhances the interconnections between human, animal, plant, and environmental health to prevent and mitigate the impacts of invasive alien species. One Biosecurity underpins three initiatives essential to deal with the pandemic risks from biological invasions: new risk assessment tools that look beyond national borders toward biosecurity risks of international concern, a stronger regulatory instrument to address biosecurity threats at a worldwide scale, and the establishment of a multilateral biosecurity convention responsible for biosecurity governance. Together, these initiatives will drive a new science and policy agenda to deliver evidence-based governance of global biosecurity.

The global response to prevent and contain the spread of the SARS-CoV-2 coronavirus undoubtedly represents the most dramatic biosecurity response ever undertaken at an international scale. This response contrasts markedly with the more muted international and national biosecurity strategies to manage emerging pests, pathogens, and weeds that negatively affect livestock, crops, or native species. This relative underappreciation of the risks arising from biological invasions doubtless reflects the fact that the global economic costs of recent emerging infectious diseases of humans have been huge: $40 billion for SARS-CoV in 2002–2003, $55 billion for H1N1/09 (swine flu) in 2009, and $53 billion for the Ebola outbreak in 2014 (Mackenzie 2020). Outside of human health, there are few individual invasive alien pest, pathogen or weed species that might account for such high economic costs. For example, the global annual cost of foot-and-mouth disease in livestock has been estimated to be of the order of $20 billion (Knight-Jones and Rushton 2013), whereas, for one of the most widespread insect pests of crops, the diamondback moth (Plutella xylostella), the annual costs are thought to be of the order of $4.6 billion (Bradshaw et al. 2016). But comparisons of individual taxa are misleading because the number of invasive alien pests, pathogens, and weeds worldwide is several orders of magnitude larger than the number of communicable diseases threatening human health (Seebens et al. 2017, Webber 2019). Therefore, although scenario modeling suggests that during the twenty-first century global pandemics could cost in excess of $60 billion per year (Gostin 2019), the annual cost attributed solely to invasive alien insects on goods and services worldwide is estimated to be more than $70 billion (Bradshaw et al. 2016).Despite their potentially greater economic costs, the more diffuse impacts of invasive alien pests, pathogens, and weeds, as well as their less discernible threat to human life, have resulted in a suboptimal approach to managing biosecurity risk at an international scale. The international regulatory environment addressing invasive alien species has long been recognized as ineffective as a result of strong sectorial silos that result in fractured and disjointed decision-making (Riley 2005, Shine 2007, De Poorter 2009, Outhwaite 2013, Liebhold et al. 2017). Unfortunately, the world is witnessing a global rise in the number of emerging alien species (those species never encountered as aliens before) and, in the absence of effective international regulations, these species pose a significant challenge to biosecurity interventions worldwide (Seebens et al. 2018). Inward-looking policies that solely address human, animal, plant, or environmental health are no longer fit for purpose because of the significant cross-sector impacts of invasive alien species (figure 1). Concepts such as One Medicine, One Health, EcoHealth, and Planetary Health have been proposed to bridge these sectorial divides, but they also suffer from several limitations (box 1). One Biosecurity is an alternative that provides an integrated perspective to address the many biosecurity risks that transcend the traditional boundaries of health, agriculture, and the environment including zoonotic parasites, vectors of pathogens, pests of agriculture or forestry, and threats to biodiversity (Hulme 2020).

Figure 1.

Interrelationships between human (couple with wheelchair), animal (cow), plant (wheat), and environmental (boar, tick, and thistle) health in relation to the impacts of invasive alien parasites, pathogens, insect pests, vectors, weeds, and feral vertebrates. A single example of each interaction is also provided for illustrative purposes. The figure emphasizes that a sectorial focus through the International Plant Protection Convention (plant health), the World Organisation for Animal Health (animal health), the Convention on Biological Diversity (environmental health), or the World Health Organization (human health) cannot capture the multiple direct and indirect effects of invasive alien species on human quality of life and well-being. The three links between human, animal and environmental health at the center of the figure capture the main areas encompassed by the One Health concept and highlight the much broader scope of One Biosecurity, which extends more comprehensively into plant and environmental health.

Figure 1.

Interrelationships between human (couple with wheelchair), animal (cow), plant (wheat), and environmental (boar, tick, and thistle) health in relation to the impacts of invasive alien parasites, pathogens, insect pests, vectors, weeds, and feral vertebrates. A single example of each interaction is also provided for illustrative purposes. The figure emphasizes that a sectorial focus through the International Plant Protection Convention (plant health), the World Organisation for Animal Health (animal health), the Convention on Biological Diversity (environmental health), or the World Health Organization (human health) cannot capture the multiple direct and indirect effects of invasive alien species on human quality of life and well-being. The three links between human, animal and environmental health at the center of the figure capture the main areas encompassed by the One Health concept and highlight the much broader scope of One Biosecurity, which extends more comprehensively into plant and environmental health.

Box 1. Progressing from One Health to One Biosecurity.

Emerging from the idea of One Medicine, the One Health concept was formalized in 2007 with the aim of bringing veterinary and human health closer together because the divide between veterinarians and doctors was seen as an obstacle to addressing the many new or reemerging human diseases that come from animals (Monath et al. 2010). Although several definitions of One Health exist, the One Health commission (onehealthcommission.org) defines it as “a collaborative, multisectoral, and transdisciplinary approach—working at local, regional, national, and global levels—to achieve optimal health and well-being outcomes recognizing the interconnections between people, animals, plants and their shared environment.” One Health has gained considerable momentum and in 2010, the WHO, the OIE, and the Food and Agriculture Organization of the United Nations (FAO) agreed to a mandate of sharing responsibilities and coordinating global activities to address health risks at the animal–human–ecosystems interface (Khan et al. 2018). However, despite this momentum, the incorporation of environmental perspectives in One Health remains limited. For example, a systematic review of the major discipline areas covered in publications addressing “One Health” catalogued in the Web of Science between 2007 and 2020 highlights that only 7% encompass environmental sciences (see below).

Furthermore, a detailed assessment of One Health networks across the world revealed that one third don't address environmental science at all (Khan et al. 2018). It has therefore been argued that the limited engagement with environmental science severly limits the application of One Health to address the global challenges facing human well-being (Destoumieux-Garzon et al. 2018, Essack 2018). As a result, alternative concepts such as EcoHealth and Planetary Health have emerged that have a stronger emphasis on the environment but these have served only to add confusion as to the best way to address the interface between human, animal, plant and environmental health (Lerner and Berg 2017). Although wildlife reservoirs, antimicrobial resistance and zoonoses are addressed by One Health, other key isues likely to shape how the world addresses the emergence of new threats to human and animal health are poorly covered. Despite the significant role invasive alien species play in determining human and animal health outcomes (see figure 1), less than 0.5% (12 out of 3952 publications) of the literature addressing One Health examines biological invasions. Important issues that have been given scant attention in One Health (and for that matter in EcoHealth and Planetary Health) include the role of international trade and human travel, the utility of international protocols for sanitary inspections of imports and exports, the effectiveness of biosecurity interventions at international borders as well as at the farm gate, and the functionality of risk assessment tools and forecasts to predict future threats. One Biosecurity embraces these areas much more explictly and broadens the concept of One Health to include strategies and policies for mitigating risks, provides clearer emphasis on the triggers of the global spread of disease outside of endemic areas, and more explictly integrates human, animal, plant and environmental health. After more than a decade since One Health was first conceptualised, the SARS-CoV-2 pandemic has highlighted limitation to this approach and the need to embed it within a much wider framework (de Garine-Wichatitsky et al. 2020, IPBES 2020, Ruckert et al. 2020). One Biosecuirty provides such a framework and in contrast to previous concepts, sets out a possible implementation plan.

Disciplines covered in 3952 publications addressing the topic “One Health” published between 2007 and 2020 as catalogued in Web of Science.

Disciplines covered in 3952 publications addressing the topic “One Health” published between 2007 and 2020 as catalogued in Web of Science.

One Biosecurity argues for greater harmonization of approaches to biosecurity threats affecting, human, animal, plant, and environmental health. At the core of the international public health response to SARS-CoV-2 is the need to address the threat of a pandemic. However, despite many invasive alien species having become established on multiple continents to the extent of effectively becoming pandemic threats (figure 2), biosecurity interventions to prevent biological invasions rarely target the risk of global proliferation. It is time for a shift in biosecurity strategies from the current focus of protecting individual countries from invasive alien species to a future emphasis on preventing the pandemic proliferation of emerging invaders across the globe. Therefore, rather than the current paradigm of preventing entry to invasive alien species through border inspections and quarantine, a more effective approach may be to prevent the deliberate or accidental export of emerging threats with potential for pandemic invasions.

Figure 2.

Frequency of with which species listed as among 100 of the World's Worst Invasive Alien Species (www.iucngisd.org/gisd/100_worst.php) are recorded as invasive in the Invasive Species Compendium (www.cabi.org/ISC). Although only meant to be representative, the taxa included among the 100 of the World's Worst Invasive Alien Species have been widely used to examine vulnerability of biodiversity hotspots to invasion (Bellard et al. 2014), the impact of climate change on biological invasions (Bellard et al. 2013), and regional management of invasive alien species (Faulkner et al. 2020). Only 91 of the 100 species were recorded as invasive in the Invasive Species Compendium, but over two-thirds have invaded three or more continents.

Figure 2.

Frequency of with which species listed as among 100 of the World's Worst Invasive Alien Species (www.iucngisd.org/gisd/100_worst.php) are recorded as invasive in the Invasive Species Compendium (www.cabi.org/ISC). Although only meant to be representative, the taxa included among the 100 of the World's Worst Invasive Alien Species have been widely used to examine vulnerability of biodiversity hotspots to invasion (Bellard et al. 2014), the impact of climate change on biological invasions (Bellard et al. 2013), and regional management of invasive alien species (Faulkner et al. 2020). Only 91 of the 100 species were recorded as invasive in the Invasive Species Compendium, but over two-thirds have invaded three or more continents.

To address the pandemic risks posed by emerging invasive alien species requires fresh thinking to identify more targeted solutions to global biosecurity threats. Using the experiences of international public health in addressing recent infectious disease pandemics, three interrelated initiatives would appear essential to deal with the pandemic risks from biological invasions: an improved approach to risk assessment that looks beyond national borders toward global risk, a stronger regulatory instrument to address biosecurity threats at a worldwide scale, and the establishment of an overarching organization responsible for international biosecurity governance. The following sections discuss how each of these three initiatives might improve biosecurity strategies to limit the pandemic threat from emerging invasive alien species but also point out several important barriers to success that arise from incomplete scientific knowledge, limited global biosecurity capability, and ambivalent political support for multilateral agreements. Overcoming these barriers requires a clear roadmap based on a One Biosecurity approach that bridges the human, animal, plant, and environmental sectors. In the present article, a preliminary roadmap to the implementation of One Biosecurity is presented that sets out the advantages and challenges of different options in order to stimulate an informed debate concerning the quantum leap required to manage biological invasions effectively at a global scale. Building consensus among scientists, policymakers, and other stakeholders in terms of the best way forward is an essential first step on the long journey to designing and finally delivering a practical solution to the increasing risk of biosecurity threats worldwide.

Evolving risk assessments to address the pandemic threats of invasive alien species

At the core of the international response to emerging infectious diseases is the obligation for countries to determine whether an event occurring within their territory might constitute a threat to the wider international community (referred to as a Public Health Emergency of International Concern, PHEIC). To qualify as such a threat, an event must meet at least two of the following four criteria: The impact must be serious, it should be unusual or unexpected, there should be a significant risk of international spread, and it could pose a significant risk to international trade or travel restrictions (Rodier et al. 2007). These criteria appear equally relevant in determining whether an invasive alien species has a high pandemic risk potential and could be classed as a Biosecurity Risk of International Concern. This would identify any emerging invasive alien species that has the potential to spread worldwide. However, the application of these criteria to biosecurity threats posed by invasive alien pests, pathogens, and weeds faces at least four major challenges to initiating a global biosecurity response.

First, in most invasive alien species incursions (with the exception of many pathogens), the species is initially identified before any impacts are documented within the territory and these impacts may occur several years after the first arrival of the species (Jarić et al. 2019). In stark contrast, often a new or emerging infectious disease is identified by its impact on human or animal health before the etiologic agent is identified. Such delays in the diagnosis of the etiologic agent of a new disease can be as brief as a few months in the case of SARS-CoV and Legionnaires’ disease, to several years for HIV, and, in some cases, such as Brainerd diarrhea, the agent remains a mystery even after several decades of research (Honigsbaum 2019, Osterholm and Olshaker 2020). As a result, public health interventions to new infectious disease threats are mobilized in response to observed impacts rather than simply the appearance of a new agent. However, even for widely established invasive alien species there remain significant gaps in the quantitative knowledge of impacts on the environment, economy, and human health (Kumschick et al. 2015). For example, using the International Union for Conservation of Nature's Environmental Impact Classification of Alien Taxa impact framework (Blackburn et al. 2014), data on the environmental impacts of invasive alien species were deficient for 18% of plant species (Rockwell-Postel et al. 2020), 24% of gastropods (Kesner and Kumschick 2018), 61% of amphibians (Kumschick et al. 2017), and 70% of birds (Evans et al. 2016). Similarly, although considerable efforts have been made to collate information on the economic costs of biological invasions, contemporary data only encompass a fraction of all invasive alien species (Diagne et al. 2020). Therefore, it is hard to forewarn the world of an impending global threat when an invasive alien species impacts have yet to be quantified (PHEIC criterion 1).

Second, the arrival of a nonnative species known to already cause problems in other parts of the world might no longer qualify under the criterion of being unusual or unexpected (PHEIC criterion 2). Data on potential impacts of an invasive alien species are often assembled from existing literature and risk assessment tools rely heavily on evidence of invasion elsewhere (Hulme 2012). The dependence on evidence of invasive alien species impacts from other regions to signal a potential biosecurity threat of global significance may represent a situation akin to closing the stable door after the horse has bolted. The fact that a species has already caused sufficient problems in other parts of the world for its impacts to be documented would mean that the invasive alien species of interest would have already begun to spread internationally. On the other hand, any new or emerging invasive alien species threat with no record elsewhere in the world would require that the seriousness of any impacts initially be quantified through the collection of original data to confirm its threat status. This would likely lead to delays, and therefore, the subsequent information on threat status could prove less effective for early warning. This could be a significant limitation to managing future biosecurity risks given the marked rise in the number of emerging alien species (Seebens et al. 2018). Thankfully, in most cases, the global spread of invasive alien species tends to be measured in years rather than in weeks, potentially presenting a crucial window for information gathering and dissemination (figure 3). However, new risk assessment tools that are less dependent on the history of invasion elsewhere are needed.

Figure 3.

Illustration of the global patterns of pandemic spread for four invasive alien species. (a) The spread of SARS-CoV through the international movement of infected humans from China between January and April 2003 (Hempel 2018). (b) The global redistribution of the red swamp crayfish (Procambarus clarkii) as a result of escapes from aquaculture (Oficialdegui et al. 2019). (c) Worldwide dissemination of the bronze bug (Thaumastocoris peregrinus) on infested plant material to regions in which its Eucalyptus hosts have been planted commercially (Machado et al. 2020). (d) Invasion of the harlequin ladybird (Harmonia axyridis) following its global transport and deliberate releases as a biological control agent (Lombaert et al. 2010). For the sake of clarity, not all known movements of each taxon are represented on the maps. The large circle represents the approximate putative origin of the invasive alien species and the dates reflect the most likely arrival in a region.

Figure 3.

Illustration of the global patterns of pandemic spread for four invasive alien species. (a) The spread of SARS-CoV through the international movement of infected humans from China between January and April 2003 (Hempel 2018). (b) The global redistribution of the red swamp crayfish (Procambarus clarkii) as a result of escapes from aquaculture (Oficialdegui et al. 2019). (c) Worldwide dissemination of the bronze bug (Thaumastocoris peregrinus) on infested plant material to regions in which its Eucalyptus hosts have been planted commercially (Machado et al. 2020). (d) Invasion of the harlequin ladybird (Harmonia axyridis) following its global transport and deliberate releases as a biological control agent (Lombaert et al. 2010). For the sake of clarity, not all known movements of each taxon are represented on the maps. The large circle represents the approximate putative origin of the invasive alien species and the dates reflect the most likely arrival in a region.

Third, although the majority of risk assessment approaches addressing biosecurity threats evaluate the extent to which an invasive alien species might spread within a specific target region, they do not address PHEIC criterion 3 in relation to the likelihood that a species could subsequently spread internationally (Roy et al. 2018). In international public health the distinction is made between pathogens of pandemic potential and those of only epidemic or regional potential (Osterholm and Olshaker 2020). Although the precise definition of pandemic has been subject to some controversy, a standard definition is of an epidemic occurring worldwide, or over a very wide area, crossing international boundaries and usually affecting a large number of people (de Campos 2020). Despite the considerable concern invasive alien species pose to individual nations, relatively few invasive alien species have truly worldwide distributions with most restricted to one or a few regions of the world (Dyer et al. 2016, Bertelsmeier et al. 2017, Pysek et al. 2017). Nevertheless, many invasive alien species have become sufficiently widespread across multiple continents (figure 2) that they could be viewed as pandemic—for example, Siam weed (Chromolaena odorata), European starling (Sturnus vulgaris), Argentine ant (Linepithema humile), Asian kelp (Undaria pinnatifida). There have been few attempts to discern why some invasive alien species become pandemic, but recent analyses point to an interaction between life-history traits associated with environmental adaptability and strong associations with effective introduction pathways (Dyer et al. 2016, Bertelsmeier et al. 2017). Developing new risk assessment tools that address the pandemic, as well as the national risk of an incursion by an invasive alien species, would appear an essential step to identify any future Biosecurity Risk of International Concern but would also require an overhaul of existing approaches to risk analysis and management (Leung et al. 2012).

Fourth, although international trade is a major driver of the introduction and global proliferation of invasive alien species, the feedback to improved regulations to manage these biosecurity threats is weak (Perrings et al. 2010a). Invasive alien species can often be introduced to a country through trade as a contaminant of agricultural or forestry products (e.g., diseases, parasites, pests, and weeds), alternatively they may be deliberately imported as a traded commodity (e.g., pets, ornamental plants), or are introduced as stowaways (e.g., hull-fouling organisms) on or in mail, luggage, shipping containers, aircraft, and ocean-going vessels (Hulme 2015b). The effectiveness of regulatory policies addressing the risks from contaminants, deliberate imports, and stowaways differs considerably (Hulme et al. 2008). The Agreement on Sanitary and Phytosanitary (SPS) measures of the World Trade Organization (WTO) aims to protect human, animal, and plant health by reducing the threat of introducing pests and diseases of humans, livestock, and economically important plants as contaminants of traded agricultural commodities (Zahrnt 2011). In many cases, the risks to international trade posed by these contaminants of agricultural and forestry products are often mitigated by pre-export treatment (irradiation, heat, fumigation, etc.) of commodities (Follett and Neven 2006). Nevertheless, the SPS measures have led to several high profile disputes that have impeded international trade in relation to the threat posed by animal and plant diseases, as well as invasive alien pests of crops (Li et al. 2007, Higgins and Dibden 2011, Bown and Hillman 2017). Although several countries impose blacklists to prohibit the deliberate importation of harmful invasive alien species as pets or ornamental plants, these import bans usually involve few taxa and at best have a minor impact on bilateral or regional trade (Reino et al. 2017). Although many invasive alien pests and pathogens (e.g., ants, snails, moths) are transported globally as stowaways, with the exception of species associated with wood packaging and ballast water, there are few international regulations addressing how this introduction pathways might affect global trade (Hulme et al. 2008).

The foregoing highlights that, under the current regulatory environment, there are likely to be few consequences for international trade for most incursions of invasive alien species bar those that affect agriculture and forestry (PHEIC criterion 4). Furthermore, apart from the SPS agreement, much of the emphasis of the management of pathways focuses on reducing the risk of importing invasive alien species rather than the risk of re-exporting these species to other countries. As a result, invasive alien species posing pandemic risks such as the Asian house gecko (Hemidactylus frenatus) that continues to spread to countries across five continents as a stowaway in shipping containers and luggage (Hoskin 2011) or the Asian tunicate (Styela clava) that has been introduced to ports around the world as a biofoulant on the hulls of ocean-going vessels (Dupont et al. 2010) are ineffectively managed. If ports infested with biofouling species of pandemic potential were off limits to international shipping or countries with a high likelihood of exporting stowaway species were prevented from engaging in trade with countries at risk from such invasive alien species, the international dimension of managing biosecurity threats would change dramatically. Therefore, although there are certainly invasive alien species of pandemic potential that pose a risk across multiple continents, the absence of robust risk assessment tools to determine which species have pandemic potential and the lack of appropriate international regulations to limit the global spread of these species currently prevent the mounting of responses of a similar magnitude as a Public Health Emergency of International Concern.

Building a stronger international regulatory framework for invasive alien species

The value in declaring that an emerging invasive alien is a Biosecurity Risk of International Concern is strongly dependent on a regulatory environment that facilitates a suitable response to a pandemic risk. Once again public health initiatives may provide a useful model for such an international regulatory environment. The dramatic global response to the SARS-CoV-2 pandemic has in part reflected the effectiveness of the World Health Organization's (WHO) International Health Regulations (2005), a set of legally binding obligations, that commit the 196 contracting parties to build capacity in order to prevent, protect against, control, and provide a public health response to the international spread of disease (Jenkins 2017). In particular, the International Health Regulations codified the identification and classification of a Public Health Emergency of International Concern (Gostin et al. 2020). Similarly, legal instruments bind contracting parties of the World Organisation for Animal Health (OIE) to report exceptional epidemiological events (including zoonoses) and any emerging animal diseases (Caceres et al. 2017). Driven by an understanding of One Health and the links between livestock and human infectious diseases, these two legal instruments are increasingly becoming harmonized (de La Rocque et al. 2019).

In contrast, legal instruments addressing biological invasions by invasive alien pathogens, plants, and animals are ineffective or insufficient at both the national and international levels, which has led to breaches in authority and poor enforcement capacity (Outhwaite 2017). The Convention on Biological Diversity (CBD) obliges, rather than legally binds, its 196 contracting parties to prevent the introduction of, control, or eradicate those invasive alien species that threaten ecosystems, habitats, or species (Clout and De Poorter 2005, Shine 2007). Although it is legally binding, the International Plant Protection Convention (IPPC) has an exclusive focus on plant health, and, despite the fact that the impacts on native plants are considered, the emphasis remain largely on the phytosanitary protection of ornamental, agricultural, and forestry crops (MacLeod et al. 2010). Long-standing proposals for better integration of the IPPC and OIE under either a new or an existing binding agreement to address alien animals that are not pests of plants have had little success (Shine 2007, Ormsby and Brenton-Rule 2017). Setting standards for invasive species (other than those connected to the cause and distribution of known animal diseases and zoonoses) remains outside the OIE mandate (Kahn and Pelgrim 2010).

The foregoing highlights that an instrument similar to the International Health Regulations could be a potentially powerful tool for managing the pandemic nature of a Biosecurity Risk of International Concern, not only as a result of stronger legal basis but also the reporting requirements that effectively establish a global monitoring and evaluation system. Correspondingly, there have been calls that a global framework for managing the biosecurity threats from invasive alien pests, pathogens, or weeds should be closely based on the International Health Regulations addressing infectious human diseases (Perrings et al. 2010a, Perrings et al. 2010b, Keller and Perrings 2011). These authors argued that bringing the International Health Regulations and the SPS agreement into conformity with one another would provide a means to build capability in developing countries, improve standards for the reporting of incursions and strengthen biosecurity responses, although the precise mechanism for achieving this goal has not been elaborated (Perrings et al. 2010a, Perrings et al. 2010b, Keller and Perrings 2011). However, at least three factors limit to the effectiveness of the International Health Regulations in preventing and controlling the spread of human infectious diseases and they provide important lessons for the usefulness of similar regulations for dealing with more general biosecurity pandemics.

First, despite over a decade of capacity building, only one third of countries currently meet the core capacities to implement the International Health Regulations because of insufficient resources or willingness to comply (Taylor et al. 2020). The International Health Regulations obliges member states to collaborate in mobilizing financial resources to improve their core capacity, but the regulations do not include any concrete financing mechanisms. Even in countries in which public health capability is strong, the responses to SARS-CoV-2 have been seen as inadequate (Aitken et al. 2020). Countries are generally overconfident in their ability to deal with public health emergencies and this is especially true in more developed nations (Tsai and Turbat 2020). This parlous state of affairs is likely to also be true for biosecurity capability. Indeed many countries in Africa, south and central Asia, Indochina, the Balkans, and South and Central America have limited response capacities to address biological invasions (Early et al. 2016). Although there have been repeated calls to increase the global capacity to manage biological invasions (Shimura et al. 2010, Liebhold et al. 2017, Measey et al. 2019), there have been few initiatives established to achieve this goal. It is evident that even with a legally binding international instrument, achieving such a goal would require much more investment and a longer timescale than previously envisaged. An important first step would be to undertake a systematic assessment of the operational readiness of different countries to prevent, detect, and respond to new incursions of invasive alien species, as well as the extent to which funds can be easily accessed to address biosecurity threats. Only when the extent of the global capability deficit is clearly identified would it make sense to mobilize sustained multilateral and bilateral partnerships to support low-income countries make progress with their capacity to deal with global biosecurity threats.

Second, although the obligations under the International Health Regulations were intended to facilitate global cooperation, nationalistic responses have been evident in the reactions to the declaration of a Public Health Emergency of International Concern relating to SARS-CoV-2 that have seen delays in notifying outbreaks in order to prevent potential harm to trade and tourism, as well as avoid pre-emptive restrictions against the reporting country (Gostin et al. 2020). Such nationalist reactions are not unknown in the case of outbreaks of invasive alien pests or pathogens of agricultural commodities that have led to trade restrictions and international disputes (de Miranda 2012, Cardwell and Brewin 2019). Furthermore, individual companies may fraudulently claim phytosanitary compliance by falsifying documentation (Haack et al. 2014). Unless systems are in place to deal with protectionist, fraudulent, or autocratic tendencies among nations, broadening legislation to include all invasive alien pathogens, plants, and animals could increase the risk of international disputes, encourage the imposition of further nontariff trade barriers, and disincentivise the reporting of outbreaks.

Third, although individual nations have a responsibility to detect a disease outbreak that might represent a possible Public Health Emergency of International Concern, it is down to an ad hoc technical expert group to review the available scientific evidence and assess the severity of the outbreak, its potential for international spread, and the likely impact on global trade and travel. Critics have pointed out that this