Redbanded Stink Bug Survey--April 2020
The Redbanded stink bug (RBSB) is not a new pest, but its incursion into the upper reaches of the Midsouth is a relatively new occurrence. It is touted as a more destructive stink bug pest than those of other stink bug species such as the green, southern green, and brown.
The RBSB does not go through diapause or a dormant or arrested development period. In other words, this insect maintains activity year-round and therefore must have a food source during the winter months in the Midsouth if it is not killed by cold temperatures [generally several hours at ≤23 deg. F]. Since the RBSB feeds only on legumes, this means that any legume such as clovers and vetches that often grow on roadsides and ditch banks will provide an alternate food source during the winter months when soybeans are not available.
In 2017, MSU entomologists were able to accurately predict the impending threat of RBSB to the 2017 soybean crop based on ditch bank sampling that was conducted in the spring of 2017. During those samplings, they were commonly finding fairly high numbers of RBSB in crimson clover well above Highway 82, which roughly bisects the state. They also documented reproduction of the insect as early as March 2017. They surmised that these ditch bank samples were a strong indicator of the potential threat to the state’s soybean crop that would occur from RBSB infestations, which did in fact occur. This led to an annual survey of likely overwintering habitats for this insect in order to predict what their growing season numbers might be since RBSB moves into soybean from legumes where it overwinters.
A Jan. 20, 2018 post on the MCS blog site offers perspective about how winter temperatures may affect RBSB populations that would be available to infest the following soybean crop. MSU Entomologists Drs. Catchot, Cook, and Gore used the harsh temperatures in 2017-2018 winter season as an opportunity to instrument protected hiding places that were known to be inhabited by RBSB. This allowed them to monitor ambient temperatures for extended periods to determine the length of time that temperatures in these habitats were below the 23°threshold known to kill the RBSB.
Unfortunately, the COVID-19 outbreak in late winter/early spring of 2020 has severely limited the ability of MSU entomologists to conduct extensive state-wide surveys for this insect. And since the 2019/2020 winter is considered mild by normal standards, it is surmised that the RBSB likely overwintered in significant numbers in Mississippi.
The inability to conduct an extensive state-wide survey for RBSB is discussed in an Apr. 2, 2020 post on the MCS blog site. In this post, MSU Entomologists Drs. Catchot, Cook, Crow, and Gore present the limited data from surveys they have conducted in seven Miss. Counties. But the main thrust of their post is to solicit the help of independent consultants and agricultural retailers in monitoring the current status of overwintered RBSB in the state. The authors present details about how to do this (e.g. number of sweeps and sample location), what data to collect (e.g. separate counts of adults and nymphs) so that all collected data can be synchronized, and helpful tips about when and where to sample and stage of legumes to sample.
There is one statement in the Apr. 2 blog post that is worth noting. The authors state that “Planting date will be the biggest factor in determining how many insecticide applications will be required. The earlier your crop is planted, the fewer number of sprays will likely be required.”
In summary, the mild winter of 2019/2020 likely will result in damaging infestations of RBSB in soybeans in Mississippi in 2020. Since this insect is far more damaging to soybeans than other stink bug species, data from the above solicited surveys will be invaluable for producers to use to plan for RBSB infestations that will likely occur in 2020.
Click here to access the Aug. 5, 2017 MCS blog post by MSU researchers/extension specialists that contains details about treatments that can be applied to prevent this insect pest from damaging developing soybean seed late into the season. Click here for the 2020 Mississippi Insect Control Guide for current control recommendations (p. 42) for this insect. Click here for a White Paper on this website that provides a detailed discussion about RBSB.