Scientists are investigating new genetic technologies they say could help rid New Zealand of possums by 2050.
While the Otago University-led study is only exploratory, Environment Minister David Parker says using tech such as gene editing for predator control would require a "wider public conversation" - as well as specific regulatory changes that aren't being considered right now.
A team led by Otago geneticist Dr Tim Hore has been researching possum reproduction over the past three years, with a long-term goal of creating genetic control solutions.
Their project, awarded an MBIE grant in 2019, has now been boosted with a $300,000 grant from Crown-owned company Predator Free 2050 Ltd.
While some scientists and conservation advocates have said New Zealand's bold bid to be free of possums, rats and stoats by 2050 could be impossible without game-changing genetic solutions, the Government has largely held off pursuing them.
That's partly been down to the fact that such techniques haven't been fully developed yet – something Hore and his colleagues want to address.
They're exploring a new method that involves targeting and transplanting immature sex cells of possum pouch young, rather than embryonic cells, before they develop into eggs or sperm.
"We are trying to get the proof-of-process that gene editing and other forms of genetic manipulation are possible in possum," Hore explained.
"While gene editing and manipulation is routine in the early embryos of laboratory rodents such as mice, it is very difficult to alter the genetics of early possum embryos."
He said it wasn't gene modification itself that was difficult, but rather applying it to the possum that is challenging because of its unique developmental biology.
"Essentially, the early embryo is covered in a thick mucoid coat making it difficult to access their genetic material."
At first, the team proposed getting around these developmental issues in possum by applying technology routinely used to modify genes in chickens and other birds.
That involved isolating primordial germ cells - or those cells that go on to make sperm and eggs in males and females respectively - and re-injecting them back into a host.
"So far, we have been able to isolate the primordial germ cells from possum pouch young and characterise them – the next step is to transplant them into a host pouch young to see if they will graft."
By focusing on unique quirks of possum biology, the team hoped to provide the tools for developing tailored and effective strategies for possum control.
"In one scenario, such technologies could be applied to possum biocontrol to create and spread genes that reduce fitness, resulting in gradual population decline and, ultimately, local eradication."
Alternatively, he said, the gene manipulation research could lead to "massive gains" without ever requiring field release.
"We can see gene technologies accelerating control strategies in the same way it has revolutionised biomedical science - essentially by allowing us to understand what genes do."
The Government today spends more than $55m a year on possum control, on top of millions more by regional councils, while the damage inflicted by the pests cost farmers about $40m annually.
PF2050 Ltd's science director, Professor Dan Tompkins, said possums remained a serious economic and environmental threat, making their eradication a national priority.
"While the application of current tools and approaches for possum eradication will continue to improve, the scale of the Predator Free 2050 mission – national eradication – means that new solutions and approaches will also be needed."
The Government's wider strategy focuses on mobilising groups and setting up collaborations around the country; developing "new and transformational tools and techniques" to eradicate the pests; and then applying these at scale across the countryside.
It also wanted a "breakthrough science solution" capable of removing at least one small mammal predator from the mainland – and an accompanying action plan to the strategy set out seven specific goals for 2025.
But the plan didn't go as far as singling out gene editing research, which has been strictly controlled by the Hazardous Substances and New Organisms (HSNO) Act since 2003.
Hore said that, as the study didn't require field release, nor need to actually modify the genes of either the donor or the host, its first phase wouldn't require any special approvals under the act.
"However, to take it to the next stage and edit possum genes and graft those, as per the HSNO Act, we will need approval from the Environmental Protection Agency."
The EPA was aware of the research, as was the Department of Conservation.
"At the very least, this work can contribute to the 2050 vision by allowing us to understand the function of possum genes - something that has revolutionised biomedical science – and it would not ever require field release," Hore said.
"Work with GMOs under physical containment occurs throughout New Zealand in universities and research institutes with very little public reaction.
"It is unlikely there would be further reaction just because we are applying it to possums held in containment, rather than mice or sheep held in containment."
Under current laws, any research involving genetically modified animals outdoors required EPA approval to carry out the work in one of four ways.
That was development via genetic modification with the animals held in outdoor containment; "field testing" the animals, but in outdoor containment; "conditional" release of the animals outside of containment with controls; and "unconditional release" of the animals into the environment.
In the first option, if the EPA deemed there would be significant public interest, it would publicly notify the application, while the second and fourth were required to be publicly disclosed under the HSNO Act, and likely require a public hearing.
In the third instance, the animals would still be considered to be GMOs, assuming approval of the application.
"The HSNO Act does allow field trials to be carried out with genetically modified organisms, provided they meet the environmental safety standards of the HSNO Act," Parker told the Herald.
"Using technology such as gene editing for predator control would require a wider public conversation, and likely regulatory or legislative changes."
While the Government was monitoring the area, the environment minister said there were no current plans to review the regulatory settings of the act for predator control.
However, he added, the Government still supported the 2050 goal and remained open to research being conducted, provided it met environmental safety standards.
Earlier this year, University of Auckland researchers modelled whether New Zealand could be kept free of rats – and found that new tools would be needed.
Those could include genetic tools that could produce a "Trojan female" whereby all male offspring are infertile, and species-specific toxins, such as norbormide, which could be highly effective and target only rats.
But they also found public buy-in would be a critical factor.
It wasn't the first time experts have warned keeping with the status quo wasn't enough to deliver New Zealand its 2050 goal, which was set under the previous National-led government.
One 2019 scientific review also found current approaches wouldn't be enough.
While it singled out some genetic techniques, the most promising ones today might not be so a decade or two from now.
It also similarly found the ability to effectively reverse some of the new technologies could be critical to gaining public acceptance - not to mention stopping them from wiping out species in other countries where they weren't considered pests.