In A Bug-eat-bug World, Researchers Use Unique Chinese Wasp To Battle Soybean Aphids

The days of soybean aphids feasting on soybean fields may be numbered, thanks to a unique import from China.

University of Minnesota scientists are field testing a beneficial insect, a stingless wasp from China also known as Binodoxys communis, that kills soybean aphids. A successful field test would be a major breakthrough in controlling a damaging crop pest. The U of M received permission from the federal government to conduct this test and is the leading institution in the testing.

Researchers look for mummies, the darker brown objects on the soybean leaf shown above,
to gauge the effectiveness of the beneficial insect in controlling soybean aphids.
The light green spots on the soybean leaf are soybean aphids.
(Credit: David Hansen, Minnesota Agricultural Experiment Station)

The soybean aphid first appeared in Minnesota fields in 2000 and today costs soybean growers an estimated $200 million annually in lost crop yields and spraying costs in Minnesota alone. The national cost is much higher.

"The soybean aphid was imported without any of its natural enemies, the organisms that keeps aphids in check in China," said Dave Ragsdale, U of M entomologist. "Our researchers and Extension experts are working to provide that check and balance system."

Multiple stages of evaluation and testing have been completed at the Insect Quarantine Facility, a joint effort between the Minnesota Department of Agriculture and the Minnesota Agricultural Experiment Station on the U of M's St. Paul Campus. Special security and air filtration systems ensure the insects being evaluated don't venture out on their own. Field testing will take place in a limited number of grower fields and at Research and Outreach Centers.

Binodoxys communis was approved for release based upon four years of laboratory safety testing. It is an especially promising species for control of soybean aphid, because it comes from a region in China that is a good climate match to Minnesota. The stingless wasp specializes in soybean aphid and has been observed apparently controlling it in China.

A cooperative effort between the U of M, the state and soybean growers, like New Richland farmer Larry Muff, have made this experiment possible.

"The soybean check off is committed to supporting research that will mitigate this devastating pest," said Muff, co-chair of the Minnesota Soybean Research and Tech Transfer Committee. "Organic growers will also benefit from this biological control of aphids."

University researchers and Minnesota Department of Agriculture scientists will monitor the ability of Binodoxys communis to kill soybean aphids this summer and continue the attack this fall when soybean aphids move to buckthorn plants and survive the winter to battle soybean aphids in 2008.

The researchers also have a backup plan. Eleven other species and strains of stingless wasps are under evaluation and some of these that have shown promise from both a safety and efficacy standpoint may be field tested in 2008.

SOURCE : University of Minnesota