Western Australian researchers are set to trial genetically modified (GM) Mediterranean fruit fly imported from the U.K. in a bid to break the pest's breeding cycle. 

The regional Department of Agriculture and Food (DAFWA) will conduct an indoor trial of a Medfly that was produced by pioneering pest control company Oxitec and possesses a gene preventing female flies from reaching adulthood.

Horticulture Director David Windsor said the innovative technique could potentially provide industry with a new means of controlling fruit fly and reducing reliance on chemical use.

"Medfly is a serious horticultural pest in Western Australia, attacking a range of cultivated fruits and some fruiting vegetables," Windsor said.

He said recent restrictions on chemical use meant there was renewed interest in innovative solutions to combat fruit fly.

"It is important to evaluate potential new sustainable control options for growers against this pest," he said.

The flies were imported as eggs and have been reared in an approved facility at the department, with glasshouse trials set to begin next year.

"The laboratory trials will determine whether the Oxitec fruit flies can be reared successfully and cost-effectively and if the males are compatible mates with the pest females."

The new technology is similar to the widely used sterile insect technique (SIT) that uses radiation to render male flies sterile and releases the flies to disrupt the breeding cycle and suppress pest fruit fly populations.

"The Oxitec technology is based on the SIT approach which we already use in WA, but instead of using radiation to render the male flies sterile, the fly is genetically modified to include a self-limiting gene," Windsor said.

"When the male flies mate, they pass on this gene to their female offspring so they do not reach maturity or lay eggs in the fruit, dramatically reducing the next generation of Medfly.

"Because these males are not exposed to radiation, it is expected they will be more competitive and active at mating than their male SIT-counterparts."

An Oxitec researcher collects Medfly embryos

Oxitec's research lead for agricultural pest control Dr Neil Morrison said new tools needed to be evaluated that could become a helpful part of integrated pest management practices to support sustainable agriculture.

"Using radiation to sterilise the flies in conventional SIT can also weaken them meaning that larger numbers are required.

"Oxitec’s approach is more targeted using a self-limiting gene to achieve the same effect.

"We believe this approach will be much more cost efficient and we aim to make monitoring much simpler as our insects carry a colour marker which makes them easy to distinguish from the real pest."

The 'self-limiting' gene is non-toxic, so the flies can be eaten by birds or other animals with no adverse effects.

Oxitec added the same pest control method had been trialed against dengue fever-carrying mosquitoes in the Cayman Islands, Panama and Brazil, successfully reducing target insect populations by over 90%.

One of many potential tools

The research in Australia is funded by the department and Horticulture Innovation Australia Limited (Hort Innovation).

Hort Innovation CEO John Lloyd said the challenges involved in controlling Medfly were many, in light of the withdrawal of organophosphates from use in Australian orchards.

"This Oxitec technology is an example of one of many potential novel tools that need to be explored in a considered manner," Lloyd said.

"In line with Hort Innovation’s position on any novel technologies, there will be an evidence-based process employed examining the research literature, credible peer reviewed data, in order to reach a sound conclusion.

"This needs to be done within the current regulatory framework."

The flies are contained to approved laboratory and glasshouse facilities and the trial is subject to quarantine and regulation conditions required by the Australian Government and the Office of the Gene Technology Regulator.

Photo: DAFWA

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