With the recent detection of seven male oriental fruit flies, Bactrocera dorsalis, near Brentwood and Oakley in Contra Costa County, authorities are quickly working to respond to this potential invasive threat. According to the Contra Costa County Agricultural Commissioner, this infestation may have knock-on effects on over 230 different fruit, vegetable, and plant commodities, such as grapes, pome, stone fruits, citrus, dates, avocados, tomatoes, and peppers.
Discovered on August 25, 2023, as part of the department's coordinated pest prevention system, the oriental fruit fly traps have been implemented in concentric circles extending 4.5 miles from the detection sites. These survey measures alone will soon to be followed up by a quarantine that is set to be announced by the California Department of Food and Agriculture.
Invasive fruit flies and other such species typically enter California through "hitchhiking" on fruits and vegetables brought in by travelers or from package shipments. Contra Costa County Agricultural Commissioner Matt Slattengren urged the public to be cautious when traveling abroad or mailing packages. He said, "When traveling abroad or mailing packages to California, we urge the public not to bring back or ship fruits and vegetables as they are pathways for oriental fruit flies and other invasive species entering our state."
In swiftly reacting to the threat, agricultural officials are adopting the principles of Integrated Pest Management (IPM). The primary eradication strategy entails using the "male attractant" technique, which has been successful in eliminating dozens of fruit fly infestations in California. As another Contra Costa County document elaborates, trained workers apply a small patch of fruit fly attractant mixed with Spinosad, a natural pesticide. The substance, which derives from a soil bacterium and is approved for use on organic crops, attracts male fruit flies who, upon consuming it, ultimately perish.
