A couple of new potential crop pests are knocking on Tennessee doorsteps. In fact, one has already been found in eastern and middle Tennessee, and the other was likely present last year (also in parts of eastern Tennessee). The brown marmorated stink bug has already been found in several counties around the Knoxville area, and there have also been confirmed reports from middle Tennessee. The “kudzu bug”, often referred to as the globular stink bug or bean plataspid has been found in Georgia, South Carolina, North Carolina, and parts of Alabama bordering Tennessee. Both of these critters are invading gifts from Asia. Both also have the habit of overwintering in and around buildings (eves, etc.) and are a nuisance to home and business owners. We will need to watch closely to see how and how far these pests will spread across Tennessee.
Kudzu Bug (Megacopta cribraria) – Although somewhat appearing like a small stink bug, especially the fuzzy immatures, this insect belongs to the family Plataspidae. Where they occur and as the name implies, the kudzu bug can be found on kudzu and other legumes, including soybean, at alarmingly high numbers. It was first found two seasons ago in several counties in Georgia. Since that time, it has spread over much of Georgia, South Carolina and into parts of North Carolina and Alabama. It is unclear how far north it might move, but indications are that it will be able to tolerate Tennessee winters. The adults are very good fliers, and they have multiple generations per year. Thus, I won’t be surprised to see kudzu bugs spread across much of the South in just a few years.
In soybean, this pest causes no obvious, immediate visual signs of injury. It does not appear to specifically attack pods. However, my counterpart in Georgia (Dr. Phillip Roberts) indicates that they have documented yield loss up to about 20% where heavy infestations were not treated with insecticides. So, it appears that kudzu bugs pose a significant threat. They have also found that a number of insecticides provide control, but the learning curve is steep on this new pest. Thanks to Dr. Jeremy Greene for sharing these pictures of this pest!
Brown Marmorated Stink Bug, BMSB (Halyomorpha halys) – This is a true stink bug (Family Pentatomidae) that attacks the fruit of many plants including corn, soybean, fruits and vegetables. The BMSB has already proven to be a significant problem to tree fruits where it occurs. It was originally introduced into Pennsylvania in 1996. By 2010, it has spread across most of Virginia and parts of Kentucky and Tennessee. Obviously, as it is spreading from the north, it is able to tolerate Tennessee winter temperatures. For row crops, the BMSB probably poses the most serious threat to soybean. My counterpart in Virginia (Dr. Ames Herbert) reported high populations in some soybean fields, particularly around field edges. In soybean, they almost certainly feed, as do our other stink bug pests, on the pods. There will likely be 2-3 generations per year possible in Tennessee. The adults are similar to general appearance to brown stink bugs.
Links for more information about brown marmorated stink bug:
Virginia Cooperative Extension – http://pubs.ext.vt.edu/2902/2902-1100/2902-1100.html