Soybean pest a tough match for plant researchers

By JOHN SEEWER

Associated Press Writer

TOLEDO, Ohio (AP) -- Researchers looking for soybean plants to stand up against attacks from a pest that spreads throughout the Midwest are fighting an elusive target.

So far, they've been able to find a few soybean genes that make the plant resistant to aphids.

The problem is the insects are able to evolve quickly, giving them the ability to make the disease resistant plants obsolete after a few years. Another stumbling block is that some plants that fight off aphids in one state don't have the same effect in another.

"The little bugs certainly know how to outwit us," said Curt Hill, a plant breeder at the University of Illinois.

Soybean aphids come from eastern Asia and began showing up in the United States eight years ago. Farmers with highly infested fields must spray expensive chemicals to combat the insect, which sucks nutrients out of plants and stunts its production.

"The best we can do is manage them," Hill said. "We're never going to eliminate them."

University of Illinois researchers found the first aphid-resistant soybean gene in 2004. It came from two soybean germ plasm lines that were grown in the South but haven't been commercially available for 30 or 40 years.

It will go on the market next year and will be marketed to farmers in the upper Midwest, including Minnesota, Wisconsin, Iowa and South Dakota. "We're not sure it's going to work in Ohio and Michigan," Hill said.

Ohio State University announced last week that its researchers have found a soybean gene that appears to be resistant to aphids in Ohio.

"It turns out the soybean aphid biotype in Ohio is different than the one in Illinois," said Rouf Mian, a molecular geneticist who works with both Ohio State and the U.S. Department of Agriculture.

Researchers don't know why aphids don't like the soybean gene they found, but they do know it repels the inspects, which live off the sap inside soybean plants, sucking out the nutritious juice.

The discovery of resistant plants has the potential to save farmers thousands of dollars they spend on chemicals. It's also significant because aphids can grow the thousand in just a few weeks, he said.

"They are continuously laying eggs," Mian said. "It's like one of those Alien movies."

Aphids also can transmit viruses among soybean and vegetable plants and travel hundreds of miles.

"Aphids can hitchhike with the wind current," Mian said. "They just float on the wind."