TONY EASTLEY: In Greek mythology, the Trojan Horse secretly carried inside it a fighting force which helped the Greek army. Now, scientists are working to identify "Trojan females" to help farmers in their battle against pests.
New Zealand correspondent Dominique Schwartz explains.
DOMINIQUE SCHWARTZ: Pests can chomp through crops, wipe out native flora and fauna, and sicken or kill animals and humans. The New Zealand government estimates that pests cost its primary industries $2 billion a year - that's money spent on control measures and money not earned due to lost production.
But professor Neil Gemmell from the Anatomy Department of Dunedin's Otago University believes a new approach to pest eradication may ease the pain - Trojan females.
NEIL GEMMELL: The Trojan female idea is that like the Trojan horse in the Troy War, it looks good but it contains something intrinsically bad for that population. And so our Trojan females, they look fine, they're normal, fertile females, but they produce sons who are infertile which is bad news for the population.
DOMINIQUE SCHWARTZ: Trojan females are not created through genetic modification, he says, but through a naturally occurring mutation in mitochondrial DNA.
NEIL GEMMELL: We could be looking for mutations that occur at a frequency of somewhere around one in 200, one in 300, maybe one in 1000. And if we can find them in large populations, which pest populations often are, identify those individuals, bring them into captive situations, breed the females up, then we have a tool potentially that we could use for eradication.
DOMINIQUE SCHWARTZ: Irradiated sterile male fruit flies have been used to control that pest in Australia for years. But the benefit of the Trojan female approach, according to professor Gemmell, is that it should be self-perpetuating.
NEIL GEMMELL: We are introducing females into the population who are going to persistently create males who are infertile, so them and their female descendants will continually produce males whose fertility is compromised.
Other fertility control strategies have generally released males whose fertility is compromised. When they die, further males need to be added.
DOMINIQUE SCHWARTZ: And arguably this approach is more humane than poisoning or trapping.
NEIL GEMMELL: The idea that individuals breed themselves to death is generally considered to be a relatively humane approach to population control. And, as I'd like to say, we control them with smiles on their faces.
DOMINIQUE SCHWARTZ: Professor Gemmell is the lead author of a paper by New Zealand and Australian scientists on the Trojan female technique. It was published last year in the Proceedings of the Royal Society.
The New Zealand government has put a million dollars into developing the technique, work being carried out by scientists on both sides of the Tasman.
DAN TOMPKINS: We're hoping that the technology that we develop here could be used to control pests in many other countries.
DOMINIQUE SCHWARTZ: Dr Dan Tompkins from New Zealand Crown agency Landcare Research is leading the project which he hopes will have many applications.
DAN TOMPKINS: In south-east Asia for example where rodents cause a loss of about 30 per cent of the rice crop, if we can develop a tool that can help tackle that, then we're talking about increased food security.
Other issues would be for public health, for example, so countries where mosquito-borne diseases like malaria are an issue, this would be another approach to help control those disease.
And of course rats and other vertebrates are biodiversity pests worldwide. We're hopeful that it'll be used in a lot of different places.
DOMINIQUE SCHWARTZ: He says field trials are likely to start in a few years.
For AM, this is Dominique Schwartz in Dunedin.