Kudzu bugs attack region’s soybean crop

CorrespondentJuly 28, 2013 

This summer, the Carolinas are experiencing invasion. Hordes of shiny, olive-and-brown bugs are blanketing fields, swarming up the sides of houses, sifting through cracks in corporate buildings, even seeping into computer servers.

They are kudzu bugs, an accidental invader from Asia, and they are covering the Southeast at a rate so rapid that that almost each week this year has brought news of yet a new county where they’ve been spotted.

Nightmare for farmers

What might sound like the dream insect for the South – a bug that eats kudzu – is turning into a nightmare for farmers. Since the Megacopta cribraria was first found in Georgia in 2009, it’s moved on from its namesake food to devour a major crop for regional growers: soybeans.

Dominic Reisig, N.C. State University assistant professor and extension specialist in the department of entomology, spends many of his days following North Carolina farmers around their fields, examining the damage done by the invasive bugs.

“When you go to a soybean field that has (them), it’s really quite impressive,” said Reisig. “They’re flying everywhere as you disturb them. You do 10 sweeps of your net and your net is loaded down. They’re getting into your boots and the folds of your pants.”

The beadlike bugs pierce stems, drink out juices and stunt the plant. Farmers have to spray their fields several more times with insecticides to control the bug, which adds costs – financial and ecological. “There’s insects in the soybean field and when you spray, you kill all the good guys,” Reisig said. “You get on the pesticide treadmill.”

Damage to farm crops is mounting.

“There’s a multimillion-dollar impact just in soybeans in North Carolina,” said Reisig. “In the South, millions more on top of that. This year is absolutely worse than last year and I think next year will be worse than this year.”

Battle plan in the works

Reisig is one of a number of scientists working on a kudzu bug combat plan – a plan that involves importing another insect. The Paratelenomus saccharalis, a tiny black wasp from Japan, lays its eggs in the eggs of the kudzu bug. Scientists are conducting extensive tests to be sure the wasp won’t become the next super pest, and so far the results are encouraging, Reisig said.

“This wasp, without exception, lays its eggs in kudzu bugs. We’ve done our due diligence; we’ve done our homework. ... We’re collaborating with other states on this. We’re really trying to do our best to eliminate the kudzu bug in a beneficial way for everybody.”

That “everybody” includes homeowners, as well as farmers. Kudzu bugs coat the outsides of homes, and even if they are sprayed with insecticide, there are plenty of replacements en route.

“I’ve had people complaining about kudzu bugs all through spring and summer. They seem to keep coming,” said Kathleen Kidd, biological control administrator for the N.C. Department of Agriculture and Consumer Services.

Other damage

In their natural environment, the bugs overwinter beneath tree bark, and “a big white clapboard-sided house looks like tree bark,” said Reisig. “Not only do they come in your house…they also have a noxious chemical they exude.” Squish a kudzu bug and you could get orange-stained skin, caustic blisters and a nasty smell that Kidd likened to “bad body odor.”

The bugs find their way into high-rises, sports stadiums, even the office. “We have had complaints from top-20 companies in the U.S. that are headquartered in North Carolina – complaints about kudzu bugs in their computer servers,” Reisig said.

Meanwhile, winter – at least a Southern winter – does little to discourage the insects. “Research shows they can survive down to 20 degrees or so, and maybe colder,” said Reisig. “We’re not going to kill them here in the state with cold.”

It all adds up to a kind of bug-mageddon. “Entomologists who are in their 70s who remember boll weevils in cotton say this kind of reminds them of that,” said Reisig. “It really is overwhelming the system.”

Fighting back

Researchers are continuing to search for multiple solutions. One of Reisig’s students is studying soybean varieties to see if any offer better resistance to the bugs.

Kidd, of the state agricultural department, is conducting a survey to see if any native insects might parasitize kudzu bug eggs. But most are pinning hopes on the wasp from the kudzu bugs’ native Japan. Some scientists are hoping the U.S. Department of Agriculture will approve release of the wasps as early as next year.

Assuming the wasps are set loose on the South, they still won’t wipe out kudzu bugs – or even greatly reduce their numbers – overnight. “We call it classical biological control,” said Reisig. “And the rule of thumb is it takes about 10 years before you start seeing an impact.”

The kudzu bug has a huge head start and it just reproduces very fast. Sort of like the vine for which it’s named. “The kudzu bug,” said Reisig, “is the insect equivalent of a weed.”

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