By Dusty Sonnenberg, CCA, Ohio Field Leader
Anytime the words “invasive species” are used to describe a new pest, people take notice. That is the hope when it comes to the brown marmorated stink bug. Kelley Tilmon, Ohio State University Extension entomologist, hopes farmers will take advantage of the new Stink Bugs pocket guide and quick reference card. The new pocket guide and quick reference cards were produced with funding from the North Central Soybean Research Program and the Ohio Soybean Council and the soybean checkoff. Stink bugs are pests that may decrease soybean yields and quality significantly without proper management. “The good news it this is a manageable pest,” Tilmon said. “Most of our pyrethroid insecticides are effective against stink bugs. The use of organophosphates is not generally recommended.” Stink bugs attack soybeans by inserting their piercing and sucking mouthparts directly into the pod and developing seed. “In essence, they feed on the good stuff that the seed needs to develop,” Tilmon said. “In fields where stink bug infestations are severe, yield losses above 20 bushels per acre have been realized. There has been over a 50% loss in seed quality in those same fields.” From a quality standpoint, pods impacted will appear to be flat where the seeds were fed on. As the pod matures and dries down, those affected seeds will appear shriveled and discolored. Depending on the stage of the soybean at the time of feeding, they may even be aborted. Another concern when it comes to yield is the potential for green stem syndrome. Green stem syndrome occurs when soybean plants stay green at the time when the leaves should be maturing (turning yellow) and dropping to the ground. This results in delayed maturity. The predominant thought is that green stem syndrome is caused by disease, insect feeding (such as stink bugs), and environmental stress during the reproductive stages of the plant. “Awareness of the pest is the first step. You will not typically notice damage by simply walking the field. Scouting involves the use of a sweep net,” Tilmon said. The economic threshold is an average of four stinkbugs in 10 sweeps for commodity soybeans. That threshold drops to an average of two stinkbugs per 10 sweeps if the beans are for seed production. Tilmon recommends scouting when soybeans are at the R3 stage of development to create a baseline. Scouting should continue throughout the remainder of the growing season. There are a variety of problematic stink bugs found in Ohio. “While the brown marmorated stink bug is the invasive species, other common species include the green stink bug, redshouldered stink bug, brown stink bug, dusky stink bug, and onespotted stink bug. All these can cause damage to soybeans,” Tilmon said. Tilmon reminds growers that if a treatment is warranted for stink bugs, to keep in mind that the later we get in the season, pre-harvest intervals could come into play. “Applicators should be sure to check the product label for the respective pre-harvest interval that must be followed,” Tilmon said.
There are also beneficial stink bugs in Ohio. The two-spotted stink bug and spined shouldered bug are predatory species. These are the good bugs,” Tilmon said. Currently a good deal of stink bug and general entomology research is being conducted in Ohio and the surrounding states. The North Central Soybean Research Program is funding studies of
the various beneficial insects that exist. Parasitoid wasps attach the eggs of stink bugs and ladybugs will feed on the stink bug eggs. Entomologists are investigating the release of beneficial insects found in Asia where the brown marmorated stink bug is native. There is also research being conducted investigating potential soybean variety susceptibility and traits.