Spotted wing drosophila (SWD) was first found in berries along the California coast in 2008. Within a year, the pest had spread from California all the way to Canada and the eastern U.S., notes Dr. Peter Shearer, strawberry entomologist with the Cal Poly Strawberry Center. Dr. Shearer is an established authority on SWD in tree fruit crops who joined the Cal Poly Strawberry Center to lead its strawberry entomology program. The Cal Poly Strawberry Center is the only organization in the U.S. solely dedicated to strawberry research and education.
Drosophila suzukii, commonly called spotted wing drosophila, is a fruit fly originally from Southeast Asia that causes significant damage to fruit crops. Unlike other common vinegar flies, spotted wing drosophila attack healthy, ripening fruit as well as damaged or rotting fruit. They can be found infesting ripening cherry, raspberry, blackberry, blueberry and strawberry fruits across the country. Economic damage estimates are staggering with some industries blaming the fly for hundreds of millions of dollars in losses.
“The spotted wing drosophila lays eggs directly in the fruit and, when the larvae hatch, the fruit collapses and decays as it is being eaten from the inside out,” explains Dr. Shearer.
SWD is less of a problem in fresh strawberries due to frequent picking, but it can become severe when growers transition from fresh to processing strawberries during the season. “The longer picking interval for processing strawberries provides drosophila ample opportunity to infect the ripening fruit,” explains Dr. Shearer.
Subhead: Management strategies
Managing SWD requires insecticide sprays, removal of overripe fruit from fields, shorter harvest intervals and cold storage of picked fruit, according to Dr. Shearer. Good sanitation is critical since infested fruit that remains in the field serves as a food source and allows eggs and larvae to fully develop, serving as a source of more flies.
“Exirel® insect control powered by Cyazypyr® active is an effective solution for managing spotted wing drosophila as well as Lepidoptera and thrips,” says Dr. Shearer. “It has a different mode of action than pyrethroids or spinosyns, providing growers another chemical class to help minimize resistance development.” Exirel insect control also has a one-day preharvest interval.
To learn more about Exirel insect control’s use on strawberries, read more here.
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