6 Nov 2014

'Trojan Females' - A Novel Idea for Pest Control

From Our Changing World, 9:06 pm on 6 November 2014

By Alison Ballance

Pest species such as rats and stoats cause large amounts of damage to native biodiversity, while insect pests such as mosquitoes are a huge health burden and also cause large amounts of crop damage every year. But researchers hope that an innovative non-lethal approach to pest management may become an important tool in the fight against pests.

The idea has been dubbed the Trojan Female Technique and involves naturally occurring mutations in maternally inherited mitochondrial DNA that produce sterile males, without affecting the female carrying them. The idea is that a female and her daughters would produce sterile males over multiple generations, leading to a steady population decline.

Geneticist Neil Gemmell from the University of Otago has a long-standing interest in mitochondrial DNA, and a few years ago recognised that some mutations reduced fertility in males - he dubbed this the Mother's Curse.

A few chance conversations seeded the idea that these mutations could be harnessed, and Neil began to talk with people such as wildlife modeller Dan Tompkins from Landcare Research. Dan has modelled different scenarios, and this work showed that introducing Trojan Females either as a single large release or a a few small repeat releases could provide effective population control in just a few generations.

The modelling showed that the technique would be most effective for species with short generation times, such as insects and rodents, although it could also be an effective way of providing long term control for species such as possums after traditional pest control methods, such as aerial 1080, have knocked populations down to low levels.

"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," siad Neil, talking to ABC earlier this year. "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."

The collaboration has just received a $1 million research grant from the New Zealand Ministry for Business Innovation and Employment to put the concept into practise in the lab, using known strains of Drosophila and lab mice that have appropriate maternally inherited DNA mutations.

The initial research has been published in the Proceedings of the Royal Society B.