Three new sterile release techniques to combat fruit fly

Three new techniques recently developed by the Department of Primary Industries (DPI) to release sterile fruit flies can significantly reduce wild Queensland fruit fly (Qfly) populations.

The sterile insect technique (SIT) is a form of biological control in which large numbers of sterile flies are released to flood the wild Qfly population, reducing the possibility of wild flies mating to produce fertile eggs.

"Historically, immature sterile flies have been released but we have recently completed a project that proves mature flies are more effective and less of them are required," said Dr Olivia Reynolds, a DPI research scientist based at the Elizabeth Macarthur Agricultural Institute (EMAI).

"In our latest project, we aimed to develop more effective sterile insect emergence and release technologies to improve the success and cost-effectiveness of SIT.

"We’ve developed guidelines for pupal (cocoon stage) release, including optimal pupal loadings and release timings that will maximise their emergence and flight activity as sterile adult Qfly.

"For adult releases, we developed a method to maximise the number of sterile male flies that emerge, their flight activity, longevity, persistence, abundance and mating competitiveness.

"Trials using chilled adult flies resulted in the development of a protocol that similarly maximises emergence, flight and longevity."

Chilling is useful because chilled flies are immobile, so space requirements (hence cost) for packaging and transport are reduced, so too are labour costs. When released, flies warm and take flight within several minutes.

"We have devised a prototype for releasing chilled adult flies from a slow moving vehicle with an automated blower – we tip chilled flies into a funnel and the blower fan pushes them out the other end into surrounding vegetation," Dr Reynolds said.

Choice of any of the three methods depends on location and available resources.

Qfly is a serious pest for a large number of horticultural industries in Australia.

Dr Reynolds says that SIT will become an increasingly valuable tool in integrated management of Qfly, especially in an era when pesticide options are diminishing.

"It is important that all affected stakeholders support further development and use of this tool."

Email: