A decade-long Kiwi research effort has turned out an ultra-targeted toxin that can eliminate rat populations while leaving other species unharmed.
A decade-long Kiwi research effort has turned out an ultra-targeted toxin that can eliminate rat populations while leaving other species unharmed.
A decade-long Kiwi research effort has turned out a targeted toxin that can eliminate rat populations while leaving other species unharmed
Regulators are now assessing the world-first rat control tool, which could prove a major boost for New Zealand’s war on bird-killing pests
Despite its potential, scientists say it shouldn’t be seen as a silver bullet, nor a replacement for contentious 1080 poison
A ground-breaking new toxin that can wipe out rats without harming other species could prove one of the biggest wins in decades for New Zealand’s war on pests.
Such is the buzz surrounding a world-first, rat-specific formulation of the toxicant norbormide, now sitting with environmental regulatorsafter a years-long research programme.
While it could offer a powerful addition to our pest-busting toolkit, scientists stress it shouldn’t be viewed as a potential replacement for effective-but-contentious 1080 poison.
Norway and ship rats are among the key pests targeted for elimination under New Zealand’s ambitious Predator Free 2050 mission – and for good reason.
Widespread in our lowland podocarp forests, they lay waste to our native birds - one estimate puts the toll at nearly 50,000 each day - and a host of other vulnerable species.
They’re also notoriously hard to trap and their populations quickly bounce back after 1080 drops.
Globally, their impacts stretch from impacts on wildlife, to damage to crops and infrastructure, to human disease: all of which has made the quest for better best control a vital one.
Over the past few years, a team of Kiwi scientists have been investigating a potent rodenticide that’s been around since the 1960s, when it was accidentally discovered in a US anti-arthritis drug discovery programme.
Norbormide was marketed as a species-selective rodenticide in the 1960s and 70s. Photo / eBay
Despite being able to kill rats inside an hour, norbormide eventually faded into obscurity as its wily target species showed they could adapt their feeding strategies to avoid it.
More recently, however, scientists have found they can trick rats into eating the toxin with “pre-baiting”, in which the rodents are enticed with a non-toxic version and then fed the lethal form.
Now, the effort - led by Kiwi company Invasive Pest Control, and involving researchers from Boffa Miskell and Auckland and Lincoln universities - is focused on how to make the product even more palatable, and efficient to manufacture.
Results of the programme, supported with funding from Crown-owned Predator Free 2050 Ltd, have been highly promising.
The team has shown they can lure rats with paste baits containing tiny amounts of norbormide, while field trials in poultry farms and native forest areas have achieved complete wipe-outs.
While the ultimate goal was a safe and ultra-targeted toxin, it wasn’t viewed as a panacea to the rat scourge.
“Norbormide is another tool in the toolbox, not a silver bullet, as it will only target rats and no other pest species,” said Dr Lee Shapiro, one of the scientists leading the work.
Dr Lee Shapiro. Photo / Boffa Miskell
Traps and other toxins would still play key roles, Sharpiro said, while norbormide might be worked into strategies to help address concerns around residue or side effects for untargeted species.
His collaborator, Professor Charlie Eason of the University of Auckland, said work was underway to meet Environmental Protection Authority (EPA) requirements for risk assessment.
“A number of these have been completed in 2024 and further studies will be completed in 2025 to enable product registration.”
An EPA spokesperson noted the toxin was a new active ingredient in New Zealand, and didn’t have contemporary approval elsewhere in the world.
“We’ve met with the applicant and their scientists on multiple occasions to discuss the information needed to ensure the health of people and the environment are protected.”
If cleared, Predator Free 2050 Limited’s Dr Dan Tompkins expected it’d be a major leap for conservation.
“Getting a norbormide bait for both ship and Norway rats over the line is the biggest advance for invasive mammal control on the New Zealand mainland, and possibly even globally, in decades.”
Predator Free 2050 science director Dr Dan Tompkins. Photo / Predator Free 2050
Protecting our under-pressure biodiversity meant eliminating rat populations or knocking them back to low numbers, which wasn’t possible with trapping alone, he said.
“So, having a rat toxin that’s harmless to other species means that we have a powerful new tool for their management in those areas where we have large concerns about non-target impacts.”
The Department of Conservation’s landscape threats science manager, Clayson Howell, agreed the toxin could be an “additional tool” for rat control.
But when it came to jointly targeting rats, possums and stoats in our rugged, inaccessible and biodiversity-rich native forests, 1080 remained the best in the bag.
“It is also biodegradable and doesn’t leave residues in the environment, making it suitable for aerial application.”
Jamie Morton is a specialist in science and environmental reporting. He joined the Herald in 2011 and writes about everything from conservation and climate change to natural hazards and new technology.
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