By SHELLY STRAUTZ-SPRINGBORN
Michigan Correspondent

EAST LANSING, Mich. — Researchers have identified a trait that provides resistance to soybean aphids. Sparta – the Soybean Aphid Shield is the new trade name for genetics developed by Dr. Dechun Wang, Michigan State University associate professor of crop and soil science.

Wang tested about 2,000 strains of soybeans against aphids to isolate four with different resistant genes. From those he developed germplasm, or seeds to breed into varieties suited to Michigan’s shorter growing season.

“The final goal,” he said, “would be to have one variety that has all those resistant genes,” maximizing protection against different biotypes of aphids and perhaps other pests such as Japanese beetle.

Soybean aphids suck plant sap and secrete sticky honeydew that promotes sooty black mold. When they sprout wings, the aphids can transmit plant viruses widely.

“In the fields, we will inoculate a plant with just two aphids, and the entire plant will be totally covered by aphids in a few weeks,” Wang said. “It takes aphids just five days to produce more babies, and aphids are born pregnant, so the regeneration cycle is incredibly fast.”

Keith Reinholt, field operations director with the Michigan soybean Promotion Committee, said soybean aphids were first identified in Michigan in 2000, with a heavy infestation in 2001. After that, he said the committee contacted researchers with the goal of identifying strategies to combat the aphids.

“The short-term solution was to find a way to manage the aphid,” Reinholt said. “We knew the long-term solution was to find a way to have resistance to the aphid.”

He said researchers approached finding the two solutions simultaneously. “We considered the damage and determined what to spray and when to spray it to control the aphids. And, we started looking at how we could find host plant resistance to the soybean aphid.”

Since 2002, the Michigan Soybean Promotion Committee has invested about $250,000 in grower revenue collected through the state’s soybean checkoff program to fund Wang’s research, earning first claim to licensing rights after MSU patented the resistance technology.

Andy Welden, who farms about 1,500 acres in Hillsdale County with his family, is pleased about the possibility of an aphid-resistant variety of soybeans.

“Soybeans are our main crop,” he said. “As a producer, we have soybean aphids most every year, but not always in a number that requires spraying. There might be some yield loss, but on the economic side of it the only method to control the aphid is with insecticides,” which he said isn’t always cost effective.

“This is another tool in the toolbox to control soybean aphids. If we don’t have to spray, I like the idea because you aren’t harming the beneficial insects. MSU educators estimate that it costs $15 an acre to make a spray application besides the time, the scouting and such.”

The germplasm already is the subject of growing interest among seed companies, which will cross it with their own varieties. The grower board will earn royalties from the sale of seed company varieties containing the trait, which Reinholt said will be reinvested in production research.

A portion of those funds will go to MSU, which will in turn distribute royalties to Wang, the College of Agriculture and Natural Resources and to the MSU Foundation.

“With one exception, all the major soybean genetics companies have licensed his germplasm because the level of resistance to soybean aphids is very high,” MSU Department of Crop and Soil Sciences Chair James Kells said. “We’re very excited about this technology, and we see great potential for commercialization and impact on soybean growers in Michigan and the U.S.”

“The real benefit to growers, in the long run, is that their technology is being used,” Reinholt added.

In addition to funding from growers, Wang’s research is supported by the Michigan Agricultural Experiment Station.