For more than a decade, Oregon State University scientists researched a fruit fly issue costing growers millions. In 2009, a berry grower in the Willamette Valley sent Oregon State University entomologists a sample of berries that were being attacked by what appeared to be common fruit or vinegar flies.
But unlike a typical fruit fly interested in soft, rotting produce, something was getting into even hard and partially ripened berries, ruining them for harvest. It was the Spotted wing drosophila, a fruit fly originating in Southeast Asia. It arrived in California in 2008 and shortly after moved up the West Coast of the U.S. and into Canada. Within three years, it had spread to every state in the country.
Walton said at first, growers used more pesticides to combat the flies, but insects eventually become resilient. Eventually one parasitoid was found that would only attack the spotted wing drosophila: a tiny wasp called ganaspis brasiliensis.
More than a decade after their research began, the scientists got approval from the U.S. Department of Agriculture late last year to raise and release the wasps in Oregon.