Gene technique could 'eradicate' New Zealand's pests

A new technique being developed at Otago University could deal the killer blow to New Zealand's country's pest problem.

The university is pioneering the Trojan female technique, in which females pass on genes that make male offspring infertile.

Professor Neil Gemmell says the technique has now been proven in the laboratory on fruit flies, paving the way for more ambitious applications.

"Our models suggest is that at worst you get phenomenal long term control of pest populations, and at best you possibly eradicate.

"This is the sort of tool where we're talking about, at least for rats and mice - 10 to 20 years with current technologies and the current ways we do things to get to a point where you might be looking at close to eradication of species."

Prof Gemmell says he's seen an 8 percent reduction per generation in fruit fly populations in the lab. That leads to a 90 percent reduction after 10 generations.

"We're not promising this is a silver bullet, we think it's very exciting new technology but it does need to be fine-tuned more."

The technology could be used to control, or even eradicate, pasture weevils, wasps, rats, mice, stoats and even possums.

The gene is found as an evolutionary accident in populations. Individuals with the dodgy mitochondrial DNA would be bred and then released into wild populations, meaning the technique avoids the use of genetically modified organisms (GMOs) and toxins.

Prof Gemmell says the technique could be ready to use within the next five years, depending on investment and uptake. But he believes it would work best when used in conjunction with existing practices.

"The way we think it might work is that you might use some form of traditional control in the first instance, you get a population down to a very low level, and then you don't actually have to introduce too many of these so called Trojan females into a population for them to have a really major effect on that population's ability to grow and persist over time."

Landcare Research's managing invasives portfolio leader Dr Dan Tompkins says the technique is currently being explored for application to pasture weevils.

"[They] cause millions of dollars of loss to the dairy and other livestock industries each year. This is particularly relevant at the moment, given data suggesting that the current biocontrol of these weevils could be failing.

"It could potentially also be used for controlling vertebrate pests, but that line of research is several years behind insect work and is currently unfunded in New Zealand."

Introduced pests are estimated to cost the country about $3.3 billion every year.

The Government announced in July last year that it wanted to make New Zealand predator-free by 2050, with a goal of eliminating all possums, rats and stoats.