Bugs a boon ... sort of
Lee Shearer @LeeShearer
A kudzu-loving bug first spotted in Georgia two years ago now has spread to three other states and shows no signs of slowing down, say University of Georgia researchers.
Properly called the bean plataspid, the tiny bugs have expanded their territory from Clarke, Oglethorpe and seven other nearby Georgia counties to an area hundreds of times larger — almost all of Georgia, all of South Carolina, a big chunk of North Carolina and four Alabama counties.
"That's a lot," said Wayne Gardner, an entomologist with UGA's College of Agricultural and Environmental Sciences. He was not talking about the territory so much as how fast the little bug is occupying new areas.
The tiny bug is well-adapted to spreading out. It flies high; Gardner last year got a call from an Atlantan who found masses of them on her 31st-story rooftop garden. They also like white cars, and Gardner suspects some may have hitchhiked on or in white cars. Recent tornados and violent thunderstorms probably have helped sweep the bugs northward also, and Hurricane Irene could push them into still more territories, he said.
Entomologists have high hopes for the little flying bug, which came from somewhere in Asia. Its primary diet seems to be kudzu, which now covers an estimated 7 million acres in the Southeast and grows as far north as Long Island.
"It grows up over the top and shades the edge trees, so they die. It kind of keeps eating away at the edge of the forest," said Jim Hanula, an entomologist with the U.S. Forest Service.
On test plots around Athens, the little plataspid reduced kudzu growth by a third, compared to plots with no bugs, he said.
Kudzu bugs also will suck nutrients from wisteria, another Asian invasive plant, Gardner said. Like kudzu, wisteria is a legume, a kind of plant that forms a partnership with a bacteria to fix nitrogen.
But the bug has a downside, too.
Bean plataspids eat other legumes besides kudzu, including soybeans. U.S. growers planted nearly 80 million acres in soybeans last year, some of it in Georgia, but mainly in the Midwest, Gardner said.
Bean plataspids could also become a threat to one of Georgia's biggest crops, peanuts, Gardner said. So far, kudzu bugs don't seem to like to eat peanut foliage. But a small genetic change might change their dietary habits, Gardner said.
When the weather turns cool in the fall, kudzu bugs also start looking for a place to overwinter, invading houses by the thousands.
Their smell is unpleasant, but otherwise they're not harmful, say the researchers.
Since homeowners began bringing kudzu bugs for identification to UGA Cooperative Extension agents in 2009, dozens of scientists at UGA and other colleges have mounted an intensive research effort, trying to answer questions such as where exactly the bug came from (probably not China, but maybe Japan), how extensively it might spread, what threat it might be to the multibillion-dollar U.S. soybean crop, and exactly what even tinier bugs live inside it — the bacteria in the kudzu bug's gut.
"We don't have the answers, but we're developing answers," Gardner said.