Kudzu bugs are non-native insects that were first detected in Georgia in 2009. Because of their behavior (they readily hitch rides in trucks and other vehicles), these unusual little brown bugs spread rapidly and made their way into Mississippi by 2012, where they quickly spread to most counties in the state. In the absence of the biological control agents that helped keep them in check in their native lands of Asia, these insects developed huge populations. Although they feed on kudzu, this is not the only legume they attack, and they can cause yield losses as high as 50% in soybeans. Kudzu bugs can also be serious household insect pests. In the fall, large numbers congregate on the sides of buildings in search of a warm place to overwinter, creating a significant nuisance for affected homeowners. Kudzu bugs have an offensive odor, and they exude a substance that can irritate the skin.
Last year, and continuing into this year, we began to notice significant declines in kudzu bug populations in areas where they had previously been abundant. States to the east began noticing this decline a year earlier. Although heavy populations continue to occur in some areas, something is attacking kudzu bugs in the Southeast and helping reduce their populations.
Actually, there are at least two different biological control agents at work. One is a tiny wasp that parasitizes the eggs. The other is a naturally-occurring fungal disease, Beauvaria bassiana, that infects many other insects. The fuzzy white growth behind the head and on the legs of the dead bug in the photo is the spores and mycelia of this fungus. Apparently, there is a strain of Beauvaria that is especially virulent to kudzu bugs. Last year, field scouts reported finding soybean fields that were “infested” with dead, white kudzu bugs, and homeowners began sending in photos of fungus killed kudzu bugs under tree bark and in other overwintering sites.
This is exactly what we hope for when a new invasive pest enters the country—that natural biological control agents show up to help control that pest. his does not mean kudzu bugs will always be kept below damaging levels. After all, most of our native insect pests have several biological control agents that attack them, but they still build to damaging levels from time to time. But at least we now have two naturally-occurring biological control agents to help control this new non-native insect pest.
Thanks to Mr. Ben Thrash, MSU entomology graduate student, for providing this picture of a Beauvaria infected kudzu bug.
Blake Layton, Extension Entomology Specialist, Mississippi State University Extension Service. The information given here is for educational purposes only. Always read and follow current label directions. Specific commercial products are mentioned as examples only and reference to specific products or trade names is made with the understanding that no discrimination is intended to other products that may also be suitable and appropriately labeled.