Harmful fruit fly found in Ashland

Will Oursler was collecting flies from the family compost pile when he scooped up a creature that researchers had been seeking for months.

The St. Mary's High School junior found an exotic pest at his home in Ashland that has plagued Oregon farmers since June, damaging cane berries, cherries, grapes and even peaches just before crops are ready to pick.

Oursler had no idea that entomologists who were researching the spread of the spotted wing Drosophila throughout the West were puzzled by its absence in Jackson County. About the same time Oursler was collecting flies in late October, the Oregon Department of Agriculture had called Rick Hilton at the Southern Oregon Research & Extension Center asking if he had heard anything.

"They told me we were the last area west of the Cascades without the spotted wing Drosophilia," Hilton said, and asked him to look around.

For his part, Hilton went out and bought some raspberries that could have been exposed to the fly. It took several days for anything out of the ordinary to emerge from the fruit he allowed to rot in a controlled area.

"I wasn't too excited about it, because there had been no positive identifications," Hilton said. "I set them aside for a couple weeks."

No sooner had the agriculture department confirmed Oursler's flies as the first spotted wing Drosophila in Jackson County than Hilton's own pests emerged.

"They just break fruit down quickly, make it unpalatable and inedible," Hilton said.

Oursler's quest began as a project for Jerry Burke's advance-placement biology class in October. He was collecting wild flies for breeding.

"My initial intent was to capture Drosophila melanogaster — the normal lab flies," Oursler said. "It took me quite a while to realize I had captured anything different."

Although his flies were bigger than the ones in the school lab, he at first discounted the idea they were anything unique.

"I figured it was because they were wild," Oursler said.

When the larvae from the four colonies he was growing at home began emerging, he had second thoughts.

"When I started breeding them, I noticed something different about them," he said. "The larvae were much larger than I expected, a lot larger."

Closer inspection revealed wing spots that none of the lab flies had. "I started searching around on the Internet and discovered the flies had been around the coast," he said.

Oursler tracked down an entomologist from the University of California, Davis, who said that he likely had Drosophila suzukii on his hands and suggested sending them to an extension agent.

"They weren't here last spring, at least as far as we know," Hilton said. "The normal fruit fly you use in the genetics lab attacks decaying or overripe fruit — the fruit you don't want any way. This fly will attack fruit right before it's ripe. People were bringing their blueberries that were looking pretty good and within a day they were a mess."

Spraying doesn't really help, he said. "You don't want to spray right before harvest."

Students and professional researchers alike will be studying the new pest's winter habits.

"I'm going to set traps out for this kind of fly and monitor how they winter and if they breed in compost," Oursler said. "They're not supposed to breed in compost. It they are, that would be unusual."

Hilton said researchers in Corvallis are developing strategies to implement before spring crops are attacked.

"They're looking at where and how well the flies winter," Hilton said. "Strawberries come early, then cherries followed by a whole string of things. How big of a problem we have remains to be seen."

Reach Mail Triibune reporter Greg Stiles at 776-4463 or business@mailtribune.com.

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