As New York state's $20 million berry industry is entering peak season, its mortal enemy, an invasive fruit fly, is thriving. However, little has been known about how the pests survive before and after the growing season.
A Cornell University study, published in Ecological Entomology, investigates for the first time what spotted-wing drosophila adults and larvae eat, and where they lay their eggs, when these short-lived fruits are not in season.
Female spotted-wing drosophila (Drosophila suzukii Matsumura) have a special ovipositor (a tube through which a female insect deposits eggs) with a saw-like end that allows them to cut into soft fruits and insert their eggs. The larvae and adults feed on the fruits, causing billions of dollars in damage across Asia, North and South America, and Europe.
"They will lay eggs and successfully develop on less preferred resources and not the typical fruit that we think they prefer," said Greg Loeb, professor of entomology at Cornell AgriTech and a co-author of the paper. Dara Stockton, a postdoctoral associate in Loeb's lab, is the paper's first author. "The more we learn about the flies, the better we can control their populations," Stockton said.
In lab experiments, the researchers found that out of 11 alternate dietary choices that included bird manure, the spotted-wing drosophila did best on diets of mushroom and mushroom-apple mixtures.
Based on numbers of flies captured in traps, spotted-wing drosophila become detectable in May, with numbers peaking in July and August, and staying consistent into December when temperatures drop below freezing. The flies can live for a full year, with a female laying up to 400 eggs over a month in non-fruit food sources in early spring.