Natural enemy suppresses kudzu bug population

By Julie Jernigan, University of Georgia

A tiny wasp — known as “Paratelenomus saccharalis” — is cutting down kudzu bug populations and Georgia soybean farmers’ need to treat for the pest, according to Michael Toews, a University of Georgia entomologist based on the UGA Tifton campus.

The wasp, an egg parasitoid and natural enemy of the kudzu bug, is saving soybean farmers time and money.

“Growers used to spray multiple times during the season, and sometimes it would do nothing to suppress the kudzu bug population,” Toews said. “Now, they just let the wasps maintain the natural balance.”

During research trials, Toews and other UGA College of Agricultural and Environmental Sciences entomologists found that the insect recently appeared in commercial soybean fields.

“There’s no manipulation or manual placement,” Toews said. “The wasps naturally find any place that is infested with kudzu bugs. We found this wasp in every field that we examined in south Georgia.”

Kudzu bugs arrived in the U.S. in 2009 and quickly spread to more than 13 states across the Southeastern U.S., devastating soybean fields. The wasp was first detected in the U.S. in 2013, far from its origins in China, India and Japan.

Toews said this natural enemy became Georgia soybean farmers’ saving grace. The kudzu bug is a major pest to commercial soybeans, causing yield losses as high as 60 percent. High populations of the pest can damage soybean’s growth, seed weight and seeds per pod.

“Growers were really struggling, and yield losses were significantly cutting into profit margins,” Toews said. “There were some general natural enemies, but the wasp clearly evolved with the kudzu bug to manage this pest.”

Growers were using insecticides to control the kudzu bug, but those proved to be destructive in many ways.

“When growers spray an insecticide, the insecticide can have detrimental effects beyond the target insect population,” Toews said. “They affect the balance of a lot of other things that weren’t pests before and upset the natural balance.”

Neither the kudzu bug nor the wasp were imported to the U.S. through formal efforts by the federal government or university scientists, Toews said. Both likely arrived through international commerce, he said.

The wasp has now been reported in Georgia, Florida, South Carolina and Mississippi.

According to the UGA Center for Agribusiness and Economic Development, soybeans generated more than $112 million in farm gate value in 2016.

For more information regarding soybeans, visit www.caes.uga.edu/extension-outreach/commodities/soybeans.html.

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