Faster ways to identify fruit flies

Technical Officer Michelle Flack analysing the genetic makeup of sterilised fruit flies, displayed on a computer screen.
Technical Officer Michelle Flack analysing the genetic makeup of sterilised fruit flies, displayed on a computer screen.

A team at the Elizabeth Macarthur Agricultural Institute (EMAI), Camden, is developing an automated, rapid diagnostic system to genotype fruit flies.

Breeding fruit flies in captivity at EMAI’s production facility generates a distinct genotype, distinguishable from wild males of the native Queensland fruit fly species.

The tricky bit has always been to differentiate wild male flies (the bad guys) from sterilised flies (the good guys) from EMAI, when the latter are released into production areas.

“Wild flies and released sterile flies are routinely caught in the trapping grid that is essential to Australia’s biosecurity,” said Deborah Hailstones, molecular biologist at Elizabeth Macarthur Agricultural Institute, Camden.

“The diagnostic team’s new assay enables rapid, reliable differentiation, speeding up the process of evaluating how effectively the sterile males are suppressing the wild population,” Dr Hailstones said.

In the Elizabeth Macarthur Agricultural Institute fruit fly factory, Laura Jiang checks pupae before they are sent for irradiation.
In the Elizabeth Macarthur Agricultural Institute fruit fly factory, Laura Jiang checks pupae before they are sent for irradiation.

The assay can identify a molecular “fingerprint” that, unlike the dye sometimes used to tag released flies, can’t be rubbed or washed off and cannot be transferred between flies caught in the same trap.

Colleagues at Sydney University, interested in the population genetics of a range of species, established a method to genotype flies which characterises nearly 30 “co-ordinates” on each fly to make up the fingerprint.

The EMAI team is working to streamline the process so that more than one co-ordinate can be generated in a single molecular reaction and so that data can be collected from up to six co-ordinates at once.

The use of robotic systems for the more mundane parts of the process further increases throughput and allows the operators to focus on more technically demanding tasks.

This will mean much faster identification of larger numbers of flies, and enable more immediate management decisions about whether or not greater eradication measures are necessary to manage the fruit fly population.