Climate change means alien invaders are more likely to wreak havoc on our wildlife, farms and economy. Those charged with repelling the threat say our isolation is no longer enough.
On a clear day in autumn, ecologists Alex Reid and Mark Yungnickel peered into the shallow waters of Bob’s Landing on Lake Karapiro. They were doing an assessment of the lakeshore and surrounding wetlands when they noticed, in about 10cm of water, the white underside of a dozen unusual-looking ribbed shellfish.
“It didn’t look like anything we knew,” says Reid. “Seeing them scattered over the substrate, we knew immediately we were looking at something strange.”
Grabbing some waders, they fished a couple of the molluscs out and took photos. These were sent to the University of Canterbury, then to the Australian Museum in Sydney. On returning to the site, the two men found, camouflaged in the yellow-brown gravelly sand, a scattering of shellfish, living and dead. A sample was sent to Biosecurity New Zealand, which sent it on to Te Papa, where staff identified it as the highly invasive gold clam Corbicula fluminea, also known as the Asian clam.
Should we be worried? The clams are prolific breeders, able to produce 400 juveniles a day and up to 70,000 a year. They have the potential to destroy native habitats and clog water supplies and hydro dams. In Europe and North and South America, says Yungnickel, they have resisted eradication efforts.
Surveys reveal the two- to three-year-old population of clams stretches one kilometre upstream and 45km downstream from where they were found – so far. Mercury Energy has reported about a dozen clams in one of its water-intake pipes at Karapiro Power Station – not enough to clog the intake for now. How did they get here? No one knows, as yet.
So far. As yet. For now. For an island country reliant on primary produce exports and tourism, with nearly 80% of our plants endemic, these phrases ought to send a shiver down our collective spine.
The stakes are high. For the 13th year in a row, industry leaders in the food and fibre sector have listed biosecurity as the top priority in the annual KPMG Agribusiness Agenda report.
Pests, mainly invertebrates and weeds, are estimated to cost our agricultural sector more than $4 billion a year. The impact of a foot-and-mouth outbreak has been valued at $15-22 billion. Brown marmorated stink bugs, regularly intercepted at the border, could devastate our fruit, vegetable and wine industries.
The PSA disease, which decimated North Island kiwifruit orchards between 2010 and 2013, is estimated to have cost the industry close to $900 million. The Ministry for Primary Industries (MPI) warned last year that, left unchecked, the bacterial infection Mycoplasma bovis could cost the dairy and beef industries up to $1.2 billion over the 10 years. As of early August, there were no confirmed cases but officials say it is too early to declare New Zealand M bovis free.
This year’s fourth International Congress on Biological Invasions, in Ōtautahi Christchurch, was a three-day call to arms against a dismal directory of scorch, rust, wilt, bloom and canker.
As post-Covid travel grows, our border systems are feeling the pressure. From January to March, security officers screened 1.4 million air travel passengers – up from 98,000 for the same period last year. Over 24,680 items, including a bag of live yabbies, were seized from air passengers compared with 1030 for the same period last year (the crustaceans, says an MPI spokesperson, were “humanely euthanised”).
To address queues, extra biosecurity lanes have been put in place to fast-track low-risk passengers, more risk-assessment podiums have been installed at Auckland Airport, and the first cohort of a total of 50 new frontline biosecurity officers have started border clearance roles across passenger, cargo and mail. Detector dogs put their noses to passenger bags; posters urge arrivals to help keep New Zealand free of foot-and-mouth disease.
At sea, during last summer’s cruise ship season, at least eight ships had to change their itineraries under new biofouling regulations aimed at protecting our marine environments from plants, algae and animals catching a lift on ships’ hulls.
Defending New Zealand
“Biosecurity is a public-good service, the same as police and defence,” says Desi Ramoo, director of B3 (Better Border Biosecurity), a biosecurity joint-venture linking research and science with government agencies and industry, “because that is what we are doing – we are defending the country.”
Much of this defence work is managed overseas. MPI has a standalone biosecurity intelligence unit monitoring overseas pests and diseases and collaborates in Australia with both the Department of Agriculture, Fisheries and Forestry and the University of Melbourne-based Centre of Excellence for Bios
ecurity Risk Analysis. Following the spread of the Japanese encephalitis virus in Australia in 2021-22, for example, New Zealand expanded its mosquito surveillance programme.
Country-specific import health standards are in place with our trading partners: biosecurity staff undertake overseas auditing of these partners’ compliance with biosecurity requirements and further inspections pick up threats at the border.
Pests and pathogens that do manage to hitch a lift across the border, or that drift in on wind, sea or a floating mat of plastic, trigger a swift response. The crop-damaging pea weevil, Queensland fruit fly, southern saltmarsh mosquito, painted apple moth, Asian gypsy moth and red imported fire ant are all listed as successfully eradicated after outbreaks in the past two decades.
Others are still “under response”. Parts of Aotea Great Barrier Island and Ahuahu Great Mercury Island have been closed to boaties and a rāhui put in place to avoid the spread of the exotic Caulerpa seaweed species. The invasive weed has been found off Kawau Island and Waiheke Island in the Hauraki Gulf in the past two months.
Others are here for the long haul. Myrtle rust, wilding pines, wallabies, velvetleaf, the oyster-killing parasite Bonamia ostreae and kauri dieback are all in “long-term management”, under which a number of agencies – the Department of Conservation, Land Information New Zealand, Crown research institutes, regional councils and landowners – try to contain their spread.
A warmer welcome
Increasing trade, new trade routes, warmer waters and milder winters will change the nature and number of what is coming at us. Bacterial leaf scorch (Xylella fastidiosa) affects grapes, olives and citrus fruit – already the bacterium has killed 1000-year-old olive trees in Italy and devastated vineyards in California. Although not here yet, warming temperatures could make much of the country a sitter for an incursion.
The fall armyworm, thought to have blown here from Australia, can feed on more than 350 plant species, particularly sweetcorn and maize. Warmer temperatures will encourage it to stay – and thrive. “In the really hot temperatures, it can have multiple generations in one year,” says Biosecurity New Zealand’s chief biosecurity officer, Stu Hutchings, “and that is when it becomes a really voracious eater.” Research is underway to try to predict where it might over-winter.
These are door knockers, searching for a foothold in this country. But while we train our gaze on the horizon, Philip Hulme, professor of plant biosecurity at Lincoln University, says we should also attend to the “sleepers” – those garden plants biding their time “in a state of fitful wakefulness”.
Getting things through the border is quite a strong filter, says Hulme, “but historically, we have not had that filter in the ornamental trade, so we have got 25,000-30,000 exotic plants growing in gardens across the country.” You have to ask, he adds, how many are spreading in the wild?
As temperatures change, those garden plants that normally die off over winter “could become marauding pests”, he says. He points to the pinwheel aeonium, a succulent flowering plant from the Canary Islands popular in private gardens. It is frost-sensitive, “but warming will give it the opportunity to germinate and spread more effectively. And they can grow on cliff faces, one of the few places where we still have our own endemic species, such as the critically threatened Lyttelton forget-me-not.”
Warmer temperatures, says University of Auckland ecologist Margaret Stanley, will also allow tropical and subtropical weeds to grow further south and on higher ground. Palms, for example. Popular in Auckland gardens, phoenix palms, bangalow palms and queen palms all produce fruits, which are dispersed by birds, “so they get around the landscape and end up in patches of bush and our native forests. Auckland has managed to get bangalow and phoenix palms banned, but by the time you ban one, the nurseries have switched to another.”
Parliamentary Commissioner for the Environment Simon Upton addressed this issue in his 2021 report “Space Invaders”. Biosecurity, wrote Upton, is overwhelmingly focused on border and pre-border measures – in other words, on what we don’t want crossing our border, “but when it comes to exotic species that have already made Aotearoa their home … legislation has little to say about where attention should be focused”.
While programmes such as Predator Free 2050 focus on our three most damaging predators – rats, stoats and possums – even the most triffid-like plants, such as wild ginger or climbing asparagus, “are unable to arouse a sense of outrage the way that a stoat filmed eating a kiwi chick can”, Upton wrote.
The Hazardous Substances and New Organisms Act serves as a filter for the introduction of new organisms – but only those not present in this country before 1998, when the act came into force. A National Pest Plant Accord between regional councils, the government and the garden plant industry lists species that should not be sold or propagated, but this list, says Hulme, is not a climate-sensitive analysis.
Each region also has its own pest management strategy to stop the sale or propagation of unwanted plants – banana passionfruit, for example, is declared a pest in Canterbury; arum lily in Auckland. But the sheer number of what’s out there, says Stanley, compared with the amount of ratepayer money available for biosecurity can be prohibitive.
“Auckland has something like 300 weed species on its management plan, but somewhere like Northland, which has a low ratepayer base, is unable to manage a lot of the species turning up there.”
Holes in the net
A 2021 report on plant biosecurity for Manaaki Whenua Landcare Research says our biosecurity system is world class but there are gaps. Gaps in expertise – especially in plant epidemiology, pasture pathology and Māori scientists working in plant biosecurity. And gaps in data. We have only limited information on endemic fungi and micro-organisms, and our ability to predict how exotic insects and pathogens will affect our native ecosystem is “poor”. In contrast to the productive sectors, it says, “there does not appear to be funding to support tracking the emergence overseas of exotic organisms that could pose new threats to our natural estate”.
Myrtle rust, for example, was regarded as a serious threat seven years before it was detected here, but little was done to prepare for its arrival: “Industry’s relatively low interest in the pathogen may have been a contributing factor.”
Lincoln’s Philip Hulme agrees. We know what eats maize, he says, “but we don’t necessarily know what eats kawakawa overseas. There may be pest species in the Pacific that currently love to eat closely related plant species to those found in Aotearoa, and they could start feeding on these natives if they should ever come over here.”
Eyes are now on rapid ‘ōhi’a death, a fungal disease decimating Hawaii’s native ōhi’a tree, a close relation to the pōhutukawa. If able to reach a warmer New Zealand, writes Margaret Stanley, the fungal disease will make myrtle rust “look like a day at the beach”.
Risk pathways
New Zealand plants in overseas botanic gardens can act as sentinels, offering an early warning system for future high-risk plant feeders and disease. But, says Hulme, these are often quite artificial environments, so if you see something eating it there, there is no guarantee they will eat it if it comes over here.
And identifying threats to our natural estate is costly. If an incursion occurs in certain productive sectors, a cost-sharing partnership between government and industry lessens the financial load to taxpayers, but there is no stakeholder voice for the natural environment.
This year’s Budget allocated $42 million for a new plant, health and environment laboratory in Auckland. It sets out to protect our environment from suspected exotic organisms, but again, the rationale appears to be weighted towards protecting our primary industries and improving crops that may do better with the changing climate.
Biosecurity NZ’s Hutchings says that in allocating funds, “we think about all the pathways of risk that things might arrive in New Zealand and make sure we have programmes in place to try to manage them across those pathways, rather than looking at the value of this or value of that and then spending accordingly”.
Work has been done to address some of the issues raised in the Landcare report. Hutchings says the agency is collaborating with universities to ensure new training programmes are in place and working with mana whenua to identify and monitor freshwater pests.
In pulling together funding and capability from across the country and matching new science research to government policy, the B3 joint venture aims not only to deliver high-quality research and science, but also keep young scientists in this country. “We fund a wide range of biosecurity research and put millions into it, then we stumble at the last hurdle,” says Desi Ramoo. “For quite a reasonable amount of money, you could take it from lab work to proof of concept. Once there, and agencies and industry see the value, they will get behind it.”
Already, B3 has been supporting projects that identify pests in the Pacific Islands, understand the potential impact of bacterial leaf scorch on our plants, adapt new sniffer technologies to the detection of pests and develop a climate-matching app that could ascertain where future successful pest incursions could originate.
It also works to bring together the Western science system and mātauranga Māori. “Māori have been practising biosecurity for a long time,” says B3 co-director Alby Marsh, “but when it comes to the regulatory system around biosecurity, they haven’t been invited to participate.
“In a [biosecurity] response, mana whenua should always be included, as they are the voice of the whenua, the ngāhere, the oceans and rivers. For Māori, it is not about economics, it is about protecting taonga, protecting their land, the water, the environment. “We need to be building these relationships in times of peace, not in times of urgency, so you can build that understanding of what the priorities are.”
Global approach
While B3 focuses largely on border security, Lincoln’s Philip Hulme wants to see biosecurity priorities extended across countries and across areas of expertise. Last year, he co-founded the Centre for One Biosecurity Research, Analysis and Synthesis (Cobras) at Lincoln University to foster a global community of researchers – vets, plant pathologists, molecular biologists, marine biologists and freshwater ecologists – to address the threats to human, animal, plant and environmental health, all under one biosecurity umbrella.
As he writes, “The days of lone entomologists or pathologists beavering away in the lab are no longer sufficient to address the social and policy challenges of biosecurity.”
He tells the Listener: “When you see an animal health risk or plant health risk, it probably has ramifications much wider than that one sector. So you need to bring everyone around the table and think of the wider ramifications of a species coming into the country and bring our expertise there.”
The giant willow aphid, for example, is assessed as a plant health risk even though willows aren’t a major issue commercially, “but the aphid exudes a lot of honeydew so wasp numbers increase, and where we have willows is often along our riverbeds and major recreational areas in our towns and cities. So, what was seen as a risk to plant health has led to a risk to human health.” A lot of these threats are cross-sectorial “but we don’t have a cross-sectorial approach”, Hulme adds.
Cobras is also global in its approach, shifting the focus from protecting individual countries to preventing the proliferation of emerging invaders across the globe.
“If you look at the fall armyworm, we probably knew it was going to be a problem 10 years ago, yet we were quite happy to watch it moving across Africa then through the Middle East and on to India and China. It was like a car crash in slow motion. We have money for overseas aid. We should be going to those countries, training them up, so they can deal with biosecurity threats that have the potential to go global.
“Dealing with it on an island or country basis just isn’t the way to go.”
This approach also calls for a clearer understanding of how pests and pathogens arrive through more detailed tracking of containers and vessels and more forensic work on particular species.
“Mycoplasma bovis – it is a European strain,” says Hulme. “They know which farm it was first detected on, so the question is, how did it get on there? Some have suggested it entered the country in imported bull semen. Often, we vilify tourists, but a lot of risks are from industries themselves.”
A new import health standard for bovine semen and embryos was introduced in 2021.
“People say myrtle rust arrived here because of a cyclone, which is blameless, but what if it wasn’t? Many Kiwis holiday in winter on the Gold Coast, the hotspot of myrtle rust. If it was tourists, we could have educated them more or swabbed people’s clothing for fungal spores. We all have our clothing swabbed for bomb material – it would be exactly the same.”
Back at Lake Karapiro, Mercury Energy is monitoring its hydro sites and putting in place measures to prevent the spread of the gold clam into different river areas. “We share the concerns of others about this new pest species and its potential threat to the river ecosystem,” a spokesperson said.
“It’s disappointing, when there is so much work from groups across the awa to build its health, to see this new threat.”
Everyone has a role to play
Responsibility for biosecurity has to be shared, says Biosecurity NZ chief biosecurity officer Stu Hutchings.
“All New Zealanders, and visitors, have a role to play, whether it’s an importing business, making sure it’s following the rules; an online shopper checking a new parcel for unwelcome insect passengers; an iwi group running a pest-management programme; a farmer reporting unusual illness in their livestock, or a traveller returning from overseas and declaring any risky goods in their luggage.”
Developed under the Biosecurity 2025 direction statement, Ka Tātou This is Us is a biosecurity “brand” designed to beef up support for biosecurity through school and community activities, the Biosecurity Business Pledge and the Biosecurity Awards.
A draft new strategy is now calling for a collaborative approach, bringing together councils, iwi, industry, research organisations, scientists, landowners, community groups and state agencies.
Still, says Hutchings, a single biosecurity institute isn’t necessary. “What we need is that everyone understands the part they have to play.” Nothing will deliver zero biosecurity risk, he says, not without closing our border to trade and travellers. Even then: “New organisms would arrive, blown in by air or in water currents. So, you have to have surveillance and then readiness programmes and money available to deal with them if they get through.”
To help prevent such incursions at the border, says Lincoln University professor of plant biosecurity Philip Hulme, we can learn from our experience of Covid. “The amount of digital information you had to share to travel was amazing – we could do that with biosecurity.
“The arrival form – you could ask questions that are more biosecurity related; you could have an app that flashes the brown stink bug when you unpack your bags.”
