Control measure

By Country News

Sterile Queensland fruit flies are set to be dropped from the sky above Cobram in a bid to curb the spread of the pest.

About two million sterile fruit flies per week will be released over about 16sqkm by a specialised small plane until the end of May with hopes the release of sterile flies will suppress the urban population and prevent it moving out into the surrounding horticultural areas.

Goulburn Murray Valley regional fruit fly co-ordinator Ross Abberfield said the release complemented the co-ordinated approach to the area-wide management of the pest undertaken as part of the GMV Regional Fruit Fly Project.

SIT is the rearing of male flies that are sterilised and released into the affected area.

The wild females that mate with a sterile male produce no offspring.

When released in large enough numbers, the release of sterile males can cause a population crash.

The release is part of a Hort Innovation project called SITplus, led by Macquarie University in collaboration with SARDI, Agriculture Victoria, NSW DPI, and Plant and Food Research.

The sterile flies arrived in Tatura last week, with the first release of sterile flies over Cobram scheduled for March 20, depending on weather.

The plane releasing sterile flies will make a limited number of passes over the Cobram urban area in a single flight, once a week during March through until about the end of May.

Sterile flies will be colour-coded by presence of a special dye visible under ultraviolet light, to distinguish them from wild flies in traps.

Additional traps will be installed around the drop zone to study the dispersal of the sterile flies and help scientists more accurately estimate the size of the wild fruit fly population.

This will inform future releases of sterile flies to ensure the ratio of sterile flies to wild flies is high enough to successfully compete with, and disrupt the breeding of, wild flies.

Cobram was selected as a release site due to its existing intensive trapping grid, the proximity of horticulture to the town, and support for the project from growers, Moira Shire Council, Berrigan Shire Council and the Goulburn Murray Valley Regional Fruit Fly Project.

The release of the sterile flies is part of a multi-pronged strategy that includes surveillance trapping, baiting, removal of unwanted or unmanaged host trees, and an extensive community awareness and education campaign.

Further releases will commence in Cobram next spring as wild flies become more active.