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News : Entomology professor reveals so-called gnats to be migrating soybean aphids

Entomology professor reveals so-called gnats to be migrating soybean aphids
by Ty Jepson Purdue Exponent
Migrating soybean aphids on Steve Yaninek

The latest buzz around campus has nothing to do with gossip, but instead with winged pests migrating through the area.

According to Steve Yaninek, head of the department of entomology, the gnats that have been swarming around campus the last few days are soybean aphids migrating from soybeans to another plant where they prepare for winter. He said the aphids are normally found on soybeans in the summertime, but in the fall they migrate to buckthorn plants to lay their eggs, which last the winter and hatch during the next warm season.

According to Yaninek, this is a cyclical process that has been fairly common in recent years.

“Widespread fall migration of soybean aphids of this magnitude has been occurring on a regular two-year cycle in odd years since the aphids were first found in Indiana in 2000,” he said.

The reason for the spikes in population, according to Yaninek, has to do with predators more than anything else.

“We believe the aphid populations build up in density in odd years because there are few ladybug predators to hold the populations in check,” he said. “This allows more fall migrants to over-winter and get a jump-start in the next season. More aphids attract more predators, which reduce the population of fall migrants in even years. I don’t expect we’ll see as many aphids next year, but we should see a burst in aphid numbers again in 2011.”

According to Yaninek, the two primary host plants, the ladybug predators and the soybean aphids themselves are all introduced species and not native to the area.

“The department of entomology has faculty and staff working with colleagues across the Midwest to control this introduced pest using a variety of methods including chemical control, host plant resistance, habitat management and biological control, (which is) good insects that eat bad insects,” he said.

Yaninek said the aphids die once they lay their eggs and should be gone in a couple of weeks.

Craig Hasbargen, a junior in the College of Technology, said he doesn’t see bugs like this in his hometown.

“They’re pretty annoying,” he said. “They get in your hair and all over your clothes.”

He said the aphids were a hassle for him in the last few days.

“I was going to the job fair the other day and they got all over my white shirt,” he said.