By Peter de Lange -, CC0

The compounding threat of invasive alien species – Expert Reaction

Biological invasions cost the global community an estimated USD$423 billion in 2019, and those costs have quadrupled every decade since 1970.

The Assessment Report on Invasive Alien Species and their Control is a new report released by the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES), looking at one of the five most important direct drivers of biodiversity loss. The authors say ambitious progress in tackling invasive alien species is achievable, but governments and different sectors have to start collaborating more to get the job done.

The SMC asked local experts to comment on the report. We’ve organised them by the following themes:

Indigenous knowledge
Freshwater and marine
Genomic tools

Distinguished Professor Philip Hulme, Lincoln University, comments:

Note: Distinguished Professor Philip Hulme is a coordinating lead author of the IPBES Assessment.

“The Assessment Report on Invasive Alien Species and their Control approved by representatives of the 143 member States of the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) is a watershed moment in our global understanding of biosecurity and biological invasions.The overwhelming evidence of major economic, social, and environmental impacts on human,animal, plant, and ecosystem health is a wake-up call to the global community to take up a more unified approach to combatting these threats worldwide.

“Aotearoa New Zealand is no stranger to these problems with a long list of threats that have been successfully averted such as the southern saltmarsh mosquito, red imported fire ant, and Queensland fruit fly. These successes and our hardline attitude towards biological invasions have established Aotearoa New Zealand as a global leader in biosecurity, a reputation we should build upon to play a key role in the development of international capacity in this field.

“The IPBES report points to key areas where the advances made in Aotearoa New Zealand can be disseminated worldwide including biological control, aerial deployment of toxins, engagement with industry, as well as our strong biosecurity governance structures. But our world-leading successes should not lead to a complacent attitude with myrtle rust, fall army worm, and the Asian clam slipping through our border controls.

“A stronger, more capable, and more aware global community is the most effective way to protect our borders by securing cleaner trade and compliant international travel. As a nation, we have a huge role to play in the leadership of any global approach and ensure that our policy research, and educational expertise is at the forefront of future developments.

“The IPBES report should therefore be seen as a catalyst for new global approach to biosecurity, one in which Aotearoa New Zealand will play a pivotal role.”

Conflict of interest statement: Coordinating lead author of the IPBES Assessment

Professor Jacqueline Beggs, University of Auckland, comments:

“The report card for introduced alien species is alarming. It’s a grim tale of devastation, with introduced species driving 60% of species extinctions, wreaking havoc on our quality of life and exacting a massive global economic toll, estimated at a whopping US$423 billion in 2019 – and costs increasing four-fold every decade. The legacy of already established species is bad enough, but the surge in the number of alien species globally is relentless. The pace of invasion is unprecedented and escalating at an alarming rate.

“New Zealand, with its unique native plants and animals, is now a battleground against alien invaders. Recent arrivals of exotic Caulerpa seaweeds threaten to smother our marine ecosystems, while the fall armyworm can attack over 350 plant species threatening food security. Most of these unwelcome guests hitch a ride on the expansion of global trade and human travel. Therefore, the need for effective border control has never been more critical. New Zealand has one of the world’s best biosecurity systems, but its effectiveness hinges on sustained funding and capacity-building efforts.

“The COVID-19 pandemic was, in essence, a biosecurity breach that underlined the formidable challenge of managing unwanted species. One invaluable lesson from this crisis was the paramount importance of collaboration to exchange ideas, align our goals, pool our expertise, leverage technology, and share vital information. Biosecurity, as a whole, stands to gain significantly from enhanced international cooperation. Moreover, adopting cutting-edge technologies for improved detection and management of introduced species is imperative. It is time to join forces and act now.”

Conflict of interest statement: “Jacqueline is the Director of the Centre for Biodiversity and Biosecurity (UoA and Manaaki Whenua, Landcare Research) and the UoA centre on climate, biodiversity and society, Ngā Ara Whetū.”

Professor Sebastian Leuzinger, School of Science, Auckland University of Technology, comments:

“The report shows alarming trends in the impact of invasive species on natural ecosystems and livelihoods. The problem is large and global, and in size matches the impacts of climate change, land use change (mainly destruction of natural habitat), pollution, and biodiversity loss, with all five intricately connected and the last one largely a consequence of the former four. The exponential trends of the number and impact of invasive species is hardly surprising in a globally highly connected world. Just a look at a visualisation of the daily shipping routes of goods globally illustrates that unintended displacements of organisms have been and will always be part of modern human civilisation. Historically speaking, a large part of human development and wealth is a direct cause of moving organisms beyond their natural boundaries.

“Tackling the problem cannot consist of blindly condemning any non-native species, instead, carefully weighing off all five mentioned environmental pressures and with a cost-benefit analysis is critical. This leads to some tricky and highly political questions in the example of Aotearoa/New Zealand: with a given amount of money, say one million $, should we attempt to remove an aggressive weed from an area, or instead plant a few hectares of pine forest (which will likely turn into native forest over time) that quickly removes carbon from the atmosphere and prevent the loss of species locally and globally through climate change mitigation?

“I think awareness in Aotearoa/New Zealand on invasive species is higher than in other places of the world, and without becoming complacent, it is fair to say that New Zealand is doing a very good job, including many decades of successful biosecurity control at our borders. The report confirms that aggressive elimination programmes are most successful on islands, and should focus on those (e.g. the pest-free islands of the Hauraki Gulf). Other attempts to combat invasives such as the Caulpera seaweed in the Hauraki Gulf are much harder and are ultimately a lost battle, so that awareness and containment of the problem might be the only solution.”

No conflict of interest.

Professor Bruce Clarkson (restoration ecologist), Environmental Research Institute, University of Waikato, comments:

“The just released IPBES report is an impressively comprehensive compilation of the research relevant to the global problem of invasive alien species. As the report notes, island nations like New Zealand remain directly in the firing line, with 20% of all impacts threatening nature and nature’s contribution to people recorded on islands.

“None of this is new to New Zealanders with numerous previous reports focusing on these issues, including the recent (2021) PCE report titled “Space invaders” on the serious and ongoing problem with weed invasion and spread.

“Professor Stoett’s optimistic concluding message that ambitious progress in tackling invasive alien species is achievable must surely be tempered by the magnitude of the resourcing lift and shift that would be needed to implement the containment and/or eradication needed to address the ever-increasing flow of ecosystem capturing alien invasives threatening New Zealand’s environment and economy.

“Two recent concerning examples of inadequate management responses in New Zealand are the national funding cutbacks for wilding pine control and the arrival of the golden clam in the Waikato River. In the first case (wilding pines), the good progress made in recent years is likely to stall and the previous investment squandered by not continuing control efforts. And in the second case, the golden clam, recognised globally as a serious infrastructure and environment threat, was overlooked for at least two years, followed by an insufficient response.

“Hopefully the IPBES report will provide further indisputable evidence that New Zealand and other countries must do better, if there is any hope of stemming the tide of alien invasive species resulting from a global transportation and economic trade model overlain by global climate change.”

Conflict of interest statement: “I am also a Waikato Regional Council Councillor but my contribution is entirely within my area of professional expertise.”

Dr Beccy Ganley, Co-Chair, Tauranga Moana Biosecurity Capital, comments:

“Tauranga Moana Biosecurity Capital (TMBC) supports global initiatives and policies that address and help to prevent the spread of invasive species within and between countries.

“Incursions of invasive and unwanted pests can affect entire communities, this includes indigenous people, the public, businesses and industries. They can have rippling environmental, economic, social and cultural impacts, which are often irreversible.

“Tauranga Moana faces numerous invasive pests that threaten our native forests, marine environments and local industries. These range from invasive weeds to devastating pathogens, such as myrtle rust, as well as unwanted organisms like the Asian paddle crabs that have invaded our environments and threaten our natural biodiversity and livelihoods.

“TMBC believes that communities, organisations and agencies both nationally and internationally need to work together and are pleased to see this report being presented to policy-makers to ensure they have the information needed to strengthen the science-policy interface for biosecurity and biodiversity.”

No conflict of interest.

Professor Amanda Black, Director Bioprotection Aotearoa, comments:

“The IPBES Assessment Report on Invasive Alien Species and their Control represents the most comprehensive assessment of the global scale of biosecurity threats. Its clear acknowledgement of the impacts of biological invasions on Indigenous Communities worldwide and the key role these marginalised groups play in implementing solutions to this problem is a marked departure from other assessments of invasive alien species. Indigenous Peoples and local communities are disproportionally disadvantaged and at greater risk due to the dependence on ecological integrity and cultural identity.

“This statement strongly resonates in Aotearoa New Zealand, where pest mammals such as deer, goats are stripping the understory of our forests and leading to massive soil erosion as observed with the recent devasting events in Tairawhiti-Gisborne following Cyclone Gabrielle, and invasive insects like wasps that cause severe economic and environmental damage, with costs to manage exceeding $150 million per year and growing, and those are only two examples of the many plaguing Aotearoa New Zealand communities.

“The key global consensus message of giving Indigenous people a stronger voice in biosecurity decision-making and the need to build capacity among local communities to address these threats resonates strongly with our mahi in Bioprotection Aotearoa. Governments worldwide have agreed as part of the Kunming-Montreal Global Biodiversity Framework to reduce the introduction and establishment of priority invasive species by 50% by 2030. While Aotearoa New Zealand is an acknowledged global leader in border biosecurity, there remains much scope to address the inequities in our biosecurity system that disadvantage our communities. This needs to happens well before 2030 if we are to have a resilient nation where future generations can thrive.”

No conflict of interest.

Dr Axel Heiser, Chief Scientist, AgResearch, comments:

“The IPBES report is an important piece of leadership in the global discussion on invasive species. It highlights the critical importance of giving this issue the attention and resource needed to address it.

“It is also highly relevant to Aotearoa-New Zealand, where so much of our economy is exposed to significant damage or catastrophe from incursions by invasive pathogens, pests and weeds.

“Most New Zealanders will be only too aware of the impact of cattle disease Mycoplasma bovis in recent years for our economy and our communities. While excellent progress has been made in the eradication effort, the effects continue to be felt by farmers and those affected communities today and industries have to remain on guard. Likewise, the arrival of the Fall armyworm pest last year is posing a significant threat to our growers and is requiring a major response effort.

“Because of these very real events, awareness of the risk of invasive alien species has been raised in New Zealand; but the report underscores the need to act in a globally unified and coordinated way.

“Our country’s agricultural sector is intricately tied to our unique ecosystems and biodiversity. As global temperatures rise due to climate change, the potential for new invasive species to establish themselves or further spread in New Zealand, increases. Certain mosquito, mite and tick species could become more prevalent and increase the risk of diseases in livestock, such as Bluetongue Virus, anaplasmosis, or theileriosis. Kudzu and other invasive weeds species could thrive in areas where they are now limited; and so could plant pests, like Brown Marmorated Stink Bug.

“New Zealand already has stringent border biosecurity measures in place to protect against invasive species. Nevertheless, as the report emphasises, there is still a substantial need for research to fill knowledge gaps and develop effective management strategies.

“We are fortunate to have strong existing collaborations such as Better Border Biosecurity (B3), which brings together the research expertise on plant pests and diseases across science providers such as AgResearch.”

No conflict of interest.

Dr Lloyd Stringer, Science group leader ecological pest management, Plant & Food Research, comments:

“Horticultural industries in New Zealand have the enviable position of achieving access for our premium temperate fruit into countries that have some of the world’s most stringent phytosanitary requirements. This is enabled by the continuous development of low input, low residue pest and pathogen management tools resulting in clean, healthy fruit with ultra-low to nil residues of non-persistent soft chemistries. Invasive species can disrupt these finely tuned production systems, and for some species like fruit flies, their presence in New Zealand can cause the immediate shut-down of access of our fruit into those valuable overseas markets.

“The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services on Invasive Alien Species and their Control highlights the challenges we face. The report emphasises the ongoing risk of invasion by invasive species as a consequence of global trade. Also of concern are those benign alien species already here that could become invasive down the track, a.k.a. ‘sleeper pests,’ if for example the environment changes, say from increased warmer winter temperatures or novel biotic interactions, that could allow them to flourish in unpredictable ways. The report shows that costs from invasive alien species are increasing by 400% every decade. For a country that is a large producer of primary products, this provides a significant challenge to production. In addition, at a societal level the costs are attributed disproportionately, with those industries involving people who are closer to the natural world most affected.

“Fortunately, New Zealand has one of the best biosecurity systems in the world. Initiatives like MPI’s Emerging Risks System provide excellent horizon scanning for future issues. Strategic partnerships such as the Government Industry Agreement for biosecurity readiness and response activities enable an increase in the co-ordination across the biosecurity continuum. Biosecurity must remain a priority area for the country and globally. This can only be achieved through robust international collaboration.”

Conflict of interest statement: “Technical Lead for the Brown Marmorated Stick Bug Council, works in biosecurity research with PFR SSIF funds via B3 (Better Border Biosecurity).”

Nicholas Ling, Associate Professor in Ecology and Biodiversity, University of Waikato, comments:

“The release of the IPBES 10 report on ‘Invasive Alien Species and their Control’ is a wake up call to governments to do more to control the spread and impacts of alien species, especially as global climate change extends the habitable zones of many exotic species and restricts the natural ranges of indigenous plants and animals.

“While the devastating impacts of terrestrial exotic species on New Zealand’s biodiversity and pastoral economy, and the ongoing costs of control programmes, are well known, less well recognised is the cost of alien species on freshwater and marine ecosystems. The recent discovery of well established populations of Asian golden clam in the Waikato River and caulerpa seaweed in Northland serve as a timely reminder that despite some of the most stringent biosecurity controls of any country, New Zealand is not immune to the introduction of new and potentially harmful alien species.

“New Zealand is considered a global hotspot for alien freshwater invasive species, with 30% of all our freshwater fish being exotic species and around the same proportion of wetland and aquatic plants. While some introduced fish like trout and salmon undoubtedly have important economic and recreational benefits, they also significantly contribute to the decline in native freshwater fish. Around 70% of endemic species are now considered threatened. Other exotic species like koi carp and bullhead catfish have little to no benefit and cause significant harm to biodiversity and water quality. Koi carp now comprise greater than 50% of all fish biomass in the lower Waikato River, and their dominance of waterways contributes significantly to poor water quality and the likelihood of toxic algal blooms. The recent introduction of bullhead catfish to Lakes Rotoiti and Rotorua is implicated in a greater than 90% decline in native kōura (crayfish).

“Globally, costs associated with exotic species now exceed NZD$700 billion annually, with costs in New Zealand estimated at greater than $1.4 billion. Predator Free 2050 is a highly ambitious and aspirational programme to rid New Zealand of pests and save our indigenous biodiversity but will struggle to succeed with the currently available tools even for the most common terrestrial pests. New Zealand is facing additional significant and escalating costs to deal with aquatic invasive species.”

No conflict of interest.

Dr. Ang McGaughran, Senior Lecturer and Principal Investigator of the Invasomics Lab, University of Waikato, comments:

“The world is under escalating threat from invasive alien species and we need to collectively up our biosecurity game. The report released by IPBES on ‘Invasive Alien Species and Their Control’ notes that invasive alien species reached a global cost of more than 423 billion in 2019. Yet, only 8% of those costs came from management (the remaining 92% relate to negative impacts like disease transmission and food supply losses).

“Although we have many of the tools required to prevent or minimise biological invasion, current measures are generally insufficient and the report outlines 40 areas where additional research is needed. Key among these current gaps are a lack of understanding of the drivers that facilitate biological invasion, and a lack of tools and frameworks for predicting invasions. Filling these gaps will lead to better preparedness and prevention, and I see genomic tools as a particularly important emerging technology for biosecurity that will help us to better predict, prioritise, detect, and manage biological invasions.

“The report also recognises that preventing and controlling invasive alien species can have positive spillover into biodiversity benefits. Indeed, biosecurity and biodiversity are two parts of the same problem. Thus, a strong theme in the report is integration, collaboration, and cross-disciplinary thinking.

“Overall, the report provides a comprehensive examination of invasive alien species – including a confronting assessment of current global trends in invasive species threats, while also providing concrete recommendations that signal hope for achievable progress against these threats moving forward.”

No conflict of interest.