UF experts: Spotted wing drosophila is pest for region's berry growers, but manageable

July 6, 2010

GAINESVILLE, Fla. — A fruit fly that has given growers in the western United States fits has made its way to the Sunshine State and may spread throughout the Southeast, University of Florida researchers say.

But while the spotted wing drosophila is likely to give Florida berry growers headaches, at least they should be of the manageable variety, said Jim Price, an associate professor of entomology with UF’s Institute of Food and Agricultural Sciences.

Price, based at IFAS’ Gulf Coast Research and Education Center in Balm, warned strawberry growers in 2009 to be on alert for the spotted wing drosophila fly, and it was found in Florida in August 2009, shortly after his forecast. It has spread to 23 South Florida counties since then, although its pace was slowed by extra-frigid temperatures this past winter, he said.

With the cold now a distant memory, the fly has made the jump from strawberry crops to blueberries in Hillsborough County, Price said.

The spotted wing drosophila is unlike many fruit flies in that it can burrow into soft-skinned fruit to lay eggs. Unlike the Mediterranean fruit fly — which recently reappeared in Florida after more than a decade — it cannot burrow into thicker-skinned fruit, such as citrus.

“So far in Florida, we have evaded commercial damage from it,” Price said. “But almost certainly now we will face a more serious challenge from it. We can’t always count on a brutal winter to knock it out, so this next season, we will have a challenge with it.”

“But there are some tools on the shelf we can use to get us through it,” he added.

Some pesticides can be effectively used to control the fly, he said.

An effective, long-term solution will likely entail having growers either remove from their fields every berry that goes bad or remove bad fruit and place it between plant beds.

Not having to remove bad berries from the fields entirely would be the easier solution, but researchers first need to know if the fly can complete its life cycle in bad fruit simply placed between beds, Price said. If that is the case, removing bad fruit completely from the field will be the only favorable option.

IFAS researchers now have established spotted wing drosophila colonies in the lab, however, and soon will be able to conduct those studies, he said.

Price said the fruit fly will almost certainly move quickly from Florida to other southeastern states. Besides blueberries and strawberries, the fly could harm other soft-skinned fruit crops such as peaches, blackberries and raspberries, Price said.

“I think this little critter is going to be able to find a home in the Southeast, beyond just peninsular Florida,” he said.