Australian scientists may have found the key to controlling fruit flies without pesticides

Bad news for female fruit flies - scientists have identified the moment the insects determine their sex, which is an important step towards creating sterile, all-male populations.

Each year the Queensland fruit fly costs fruit and vegetable producers millions of dollars in damage, but Australian scientists may now have found the key to controlling them without dangerous chemicals.

Researchers at the Hawkesbury Institute for the Environment at the University of Western Sydney and the University of New South Wales have identified the exact time when a fruit fly becomes either male or female.

Using this knowledge, the scientists are now working on mass producing generations of sterile male fruit flies, which can be released into the wild to help naturally suppress the population.

"Understanding the mechanisms and timing of how insects become either male or female is critical for the development of new bacterial or genetic approaches to pest control," lead author of the study, Dr Jennifer Morrow from the Hawkesbury Institute for the Environment, said in a press release.

The main chemical currently used to control populations is fenthion, which is about to be phased out due to concerns over health risks to humans.

The research, published in Insect Molecular Biology, looked into when genes that trigger sex determining proteins were switched on in fruit fly embryos. Using this information, the scientists found that a fruit fly’s gender is decided shortly after eggs are laid into fruit, in the early hours of embryonic development.

The challenge is now how to mass produce male-only lines.

"Our research significantly adds to understanding the key process of sex determination in this destructive crop pest. This knowledge could enable the industry to develop fruit fly lines that can be used to produce male-only broods in huge quantities. They may be intrinsically sterile or may be sterilised before release, for example by gamma irradiation," Morrow explained.

By combining these male-only lines with the use of damaging bacteria that’s passed down through fruit fly generations, such as Wolbachia, the researchers believe they’ll be able to find new, environmentally friendly ways to control the population.