“If a kudzu bug population grows large enough, it’s capable of wiping out these two crops,” Hu says. “In fact, we have photos showing as many as 50 bugs on only one long bean pod.”

Some plants have died from bug infestations. The same holds true for several other vegetable corps, such as lima beans, runner beans and string beans.

Hu has also discovered the female’s ability to store sperm during the over-wintering period — a rare trait among insects and one that provides the species with an especially valuable survival tool.

“The sperm can survive the entire winter, after which the stored sperm is released and the eggs fertilized,” she says.  “What this means is that a female kudzu bug doesn’t need the presence of males when she flies to a new location to over-winter.”

Hu has also gained new insights into how females lay their eggs, depositing them strategically in early spring before the primary hosts, kudzu and soybeans, begin budding and leafing.

She says the females often deposit egg masses on low plants close enough for fast-growing kudzu to reach. Females have also been found depositing egg masses on tall plants and trees farther away so that the hatched larvae are blown by wind into the kudzu — a highly evolved dispersal method, she says.

Hu has also determined that kudzu bugs migrate into soybeans only after the plants have reached a foot in height. 

She hopes these findings will provide homeowners and farmers alike with more effective methods to remove habitats that promote the pest’s spread.

The biggest breakthrough of all is the detection of a native parasitoid found in the guts of several kudzu bugs dissected by Hu’s graduate student researcher, Julian Golec.

The parasitoid, which Hu has determined to be a fly, ultimately could reduce the kudzu bug’s numbers substantially over the next few years and may also prove to be an effective biological method to complement future control strategies.

“The presence of this parasite in the bugs we’ve detected is unusually high,” she says. “We’ve even seen the larvae crawl out from several of the insects, pupate on the ground and emerge into flies, which, in turn, affect other bugs.”

Hu has determined the family and genus of the fly and hopes to release it within the next few weeks. Her next research priority is to determine conditions for optimizing the parasite’s numbers.

“The discovery of this parasite is especially good news, as it may provide a viable alternative to an imported wasp species, allowing nature to take the exotic kudzu bug to task,” Hu says.

To date, the pests have spread to 56 of Alabama’s 67 counties since 2009.

 

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