Kudzu bug may be a game changer for soybean growers, but biocontrol discoveries are promising

When the kudzu bug (Megacopta cribraria) was first discovered in the southeastern U.S. in 2009, its establishment received mixed reviews. Some welcomed it with cautious optimism because of its predation of kudzu; however, homeowners who tried futilely to banish the pest from their houses and yards wanted it to make a quick exit. When soybean growers discovered that the pest was decimating their crop, the kudzu bug soon became an unwelcome guest, and scientists rushed to find economical control options. In the past two years, scientists have discovered some biological control agents for kudzu bug that may help reduce the need for pesticides to control the pest.

Kudzu bug was first discovered on homes in Georgia in 2009. Because many of the homes were situated close to kudzu patches, and scientists observed the insects moving from kudzu to the properties, the insect was named “kudzu bug.” Kudzu bug is attracted to light-colored objects, making houses and white porch posts an ideal resting place in between their feedings on kudzu. They are active fliers and can quickly enter a home through a briefly opened door or an open window, and if crushed against skin, the nymphs can leave orange stains and skin rashes.

When scientists first began studying the bug, they had doubts about the exact species name. Another member of the Megacopta genus, Megacopta punctatissima, has a similar taxonomy to M. cribraria. To date the species in the U.S. is named M. cribraria until further research proves otherwise.

Kudzu bug adults feeding on stem. Photo credit: Brad Fritz, Sandhills Research Station

Kudzu bug adults feeding on stem. Photo credit: Brad Fritz, Sandhills Research Station

According to a 2013 article in Applied Entomology and Zoology, kudzu bugs usually complete two generations during the growing season; the first generation usually completes development on kudzu or early-planted soybeans, and the adults can move to other legume plants. The second generation arrives in late summer on kudzu and other legumes. Females lay eggs on other plants besides kudzu and legumes, including lespedeza, wisteria, figs, peaches, pecans metal posts and other objects, but eggs do not develop successfully.

Nymphs and adults feed mainly on the stems (see photo), and sometimes on the leaves of kudzu and legume plants. They have also recently been observed feeding on the pods. The damage to the plant can reduce yields significantly depending on the insect population. In Alabama, kudzu bugs have been seen feeding on many plants other than kudzu or legumes when neither was available in early spring and later fall. Other host plants include ornamentals such as Queen Anne’s Lace.

Until recently, the best control method was broad-spectrum insecticides, which can also significantly reduce beneficial insects necessary to manage other insect pests. Growers attempting to control kudzu bug often see a rise in other insect pests. Organic producers have no recourse against the pest.

In addition to affecting domestic production, the kudzu bug has caused problems with exports. In February 2012, after inspections of containers revealed dead kudzu bugs in shipments of frozen chicken meat paste, Honduran officials refused to accept shipments of products from Alabama, Georgia and South Carolina until all containers were thoroughly inspected. USDA worked with Honduras to establish operating protocols for loading containers. To this day, concerns are high that kudzu bug will become established in Central America and Brazil.

Late instar kudzu bug nymphs. Photo by Brad Fritz

Late instar kudzu bug nymphs. Photo by Brad Fritz

At the time the 2013 article was written, researchers had not found a native predator for kudzu bug that reduced populations significantly, and no native egg predators had been discovered. Authors selected an egg parasitoid from Japan, Paratelenomus saccharalis, to undergo the rigorous USDA testing for release in the U.S. to control kudzu bug.

In the past few months, however, a research team led by Xing Ping Hu at Auburn University has discovered two possible predators that are local to Alabama. The first is a native parasitoid fly that attacks kudzu bug adults; the second is a wasp parasitoid that attacks eggs.

Hu’s graduate student researcher, Julian Golec, found the fly parasitoid in the guts of several kudzu bugs. The rate of parasitism was promising.

The newest find, the wasp egg parasitoid, parasitizes kudzu bug eggs at an even higher rate than the parasitoid fly (for adults). Hu’s graduate student observed wasps emerging from the kudzu bug eggs as fully mature adults, so the wasps can quickly affect other non-parasitized kudzu bug eggs and start the life cycle again. The males appear to emerge first and guard the parasitized kudzu bug eggs until the females emerge.

Kudzu bug eggs, photo by Brad Fritz

Kudzu bug eggs, photo by Brad Fritz

Hu says that the wasp is local (but not native) to Alabama, and she and Dr. Wayne Gardner at the University of Georgia and several other entomologists from USDA are still studying its origins and biology. While they are studying it, Hu says that the number of kudzu bugs in soybeans are already dropping significantly. Though growers in Alabama are promising to adjust their spray programs to work around the presence of the fly and the wasp, it is up to the soybean entomologists in the southeastern states to work together in making recommendations for kudzu bug control in soy crops based on the new discoveries of natural enemies.

Hu was awarded a $30,000 2013 IPM Enhancement Grant to educate growers about changes to current pest management practices based on research findings.

If the new predators can adjust to the conditions of other states infested by kudzu bug, the once menacing agricultural and urban pest may have met its match.

Media contact: Xing Ping Hu, Professor and Extension Specialist, Auburn University, (334) 844-6392 or huxingp@auburn.edu

Sources:

Ruberson, J.R., Takasu, K., Buntin, G.D., Eger Jr., J.E., Gardner, W.A., Greene, J.K., Jenkins, T.M., Jones, W.A., Olson, D.M., Roberts, P.M., Suiter, D.R., Toews, M.D. (2013) From Asian curiosity to eruptive American pest: Megacopta cribraria (Hemiptera: Plataspidae) and prospects for its biological control. Appl. Entomol. Zool. 48:3-13. Online at http://link.springer.com/article/10.1007%2Fs13355-012-0146-2.

Langcuster, J. Researcher at Auburn University targeting voracious kudzu bug. 24 July 2013. Online at http://wireeagle.auburn.edu/news/5379.

Langcuster, J. Discovery of a local wasp parasitizing kudzu bug eggs a game changes, says Auburn Researcher. 7 August 2013. Online at https://sites.aces.edu/group/comm/newsline/Lists/Posts/Post.aspx?ID=671

One Response

  1. Reblogged this on Entomology Today and commented:
    In the past few months, a research team led by Xing Ping Hu at Auburn University has discovered two possible predators of kudzu bugs that are local to Alabama. The first is a native parasitoid fly that attacks kudzu bug adults; the second is a wasp parasitoid that attacks eggs.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: