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Fruit Flies Infesting Crops

A pesky foreign fruit fly has been wreaking havoc for local berry and cherry farmers in the past few years. And this year may be worse than last, which was the worst on record, according to the Oregon State University Extension Service.

Known as the spotted wing drosophila, or Drosophila suzukii, the fruit fly attacks ripening fruit by laying eggs under the fruit’s surface. Within days, the fruit’s structure collapses, becoming a haven for maggots.

The insect is native to Southeast Asia and first appeared in California in 2008. It made its way to Oregon in 2009 and has since spread all over the state, including the southern Willamette Valley.

With help from a $5.8 million research grant from the U.S. Department of Agriculture in 2010 and funding from the state Department of Agriculture, OSU researchers have been trying to find a solution to an infestation that could cause millions of dollars in damage to Oregon crops.

But it’s not easy.

“We’re not going to get rid of them,” said Ross Penhallegon of Lane County’s OSU Extension. The California Department of Food and Agriculture has already deemed it impossible to get rid of the pest.

“So, holy moley, how do we control it?” Penhallegon said. Scientists so far know little about the insect’s biology, or effective ways to kill it, he said.

The pest could cause $31.4 million total losses for Oregon blueberry, strawberry, blackberry, raspberry and cherry farmers who experience a 20 percent damage rate, according to 2009 numbers from the National Agricultural Statistics Service. Losses for the entire West Coast — which produces all of the nation’s commercial raspberry and blackberry production — could total $511.3 million.

Penhallegon estimated that the insect has caused about a 5 percent damage rate in Lane County crops, and said he expects a “huge plight of these critters” this year because of the mild winter and warm spring. With the county’s 10,000 acres of blackberries threatened, farmers need to do something, Penhallegon said.

“People in Lane County typically don’t like the word ‘pesticide,’ ” he said, “but they also don’t like bugs in their fruits.”

Linda Brewer, OSU’s spotted wing drosophila project manager, said researchers from OSU, Washington State University, the University of California, Davis, and the University of California, Berkeley, have teamed to develop ways to help farmers kill the bugs before they kill the crops.

Brewer said they’ve used insecticides and built traps using plastic cups with apple cider vinegar in the bottom with a yellow, sticky trap inside that catches the insect.

“We were in crisis management,” Brewer said of the infestation’s first waves in 2009 and 2010. “No one knew anything about the spotted wing drosophila. We’re starting to get a grip on what are the management strategies that allow our fruit production industry to remain economically viable. We’re getting people to shift their thinking.”

Norma Grier, manager at Royal Blueberries, a family-owned organic farm on the outskirts of Eugene, said she first spotted punctures in the blueberries and noticed that the fruit was softer than usual.

“We started finding berries that were infested with maggots,” she said. “The infestation becomes unmanageable and just really bad. Even overnight, the (insects) can take your berry from a nice firm berry into one crawling with maggots.”

Grier said it’s especially difficult for her farm, which is organic, because she doesn’t like to use insecticides of any kind.

Workers this year started picking blueberries earlier than usual and stored them in the freezer to prevent larva from growing inside, she said. So far, it seems to be helping.

Although the pests pose a problem for farmers, Penhallegon said consumers are going to have to deal with the use of insecticide or face the possibility of bugs lurking inside locally grown fruit.

“I tell people that they’re getting 1 percent more protein,” he said of bugs inside the fruit. “Then they go, ‘Eew! Eew!’ In reality, though, the bugs aren’t going to hurt you. It’s all psychological. You’ll never taste it.”

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