16 Jun 2017

'Trojan Female Technique' could sterilise pest populations

5:04 pm on 16 June 2017

A new technique that could be used to eradicate pests like mice and wasps has just been proven in the laboratory on fruit flies.

The "Trojan Female Technique" is where females pass on genes that make male offspring infertile.

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The "Trojan Female Technique" could be used on other pests such as mice and wasps. Photo: 123rf

The head of the University of Otago's Department of Anatomy, Neil Gemmell, said it was not a new idea to release sterile males, but creating and releasing females that produce sterile offspring was a first for pest control.

"This is a world-first proof-of-concept and we need to test the general applicability of this approach more widely."

In a recent paper published by eLife, Professor Gemmell and co-authors reported their success in making their theory about Trojan female fruit flies a reality in the lab.

The approach doesn't require genetic modification, instead it uses naturally occurring mutations in mitochondrial DNA that affect male, but not female, fertility and fitness.

Professor Gemmell said this could be a good way to get rid of pests.

"What we've done is shown, at least in fruit flies, that if you introduce these females and produce males with compromised fertility then you can get quite significant levels of population reduction over about 10 generations of introduction."

It's a simple idea where you take the Trojan females, breed them up in captivity, and then release them into the wild, Professor Gemmell said.

"You're actually adding more pests initially but those females produce, on an ongoing basis, infertile males and as a consequence you get long-term population reduction and potentially eradication."

Not just fruit flies

Research is also being done on other pests.

"We're looking at pasture weevils as a potential target for the Trojan female approach - we have a grant from MBIE and that's led by AgResearch.

"We're also working on wasps - a major problem particularly in the biodiversity area."

Professor Gemmell said Trojan females could be a big move for pest control.

"While there are many tools to control pest populations, we think this might be an important part of a growing arsenal.

"Certainly around New Zealand there is a great deal of interest in this approach as a way to control rats, possums and stoats as part of the Predator Free 2050 goal."

The research is being funded by the Biological Heritage National Science Challenge and the Ministry of Business, Innovation and Employment.

If it works in New Zealand then there could be an opportunity to take it overseas, Professor Gemmell said.

"Maybe there is a business opportunity... how we would control the IP around it is actually extraordinarily challenging."

From the lab and into the paddock

Professor Gemmell said there were several advantages to the Trojan female approach.

"It does not require elaborate, and probably uncontrollable, delivery systems, such as parasitic vectors and intermediate hosts."

Getting it into agriculture, for example to control weevils or wasps, would not be too hard, he said.

"It's not trivial to scale this up. We're probably looking at a couple of different steps... the first is that you have to show in a laboratory or a controlled situation that the introduction of these females actually leads to reduction in population size.

"Then if it does you could potentially do experiments in controlled enclosures, and then up in increasing scales."

Professor Gemmell said to get the Trojan females onto farms, scientists would need facilites to initially breed large numbers of these species.

But he said once the species were introduced into the wild they could then be used for the next batch.

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