Evaluating neonicotinoid insecticides for systemic control of brown marmorated stink bug (Halyomorpha halys) in fruiting vegetables

The invasive brown marmorated stink bug (BMSB), Halyomorpha halys, can cause significant damage to fruiting vegetables such as pepper, tomato, and eggplant in the mid-Atlantic U.S.  Effective control of this pest has been limited to multiple foliar applications using broad spectrum insecticides (typically pyrethroids), which disrupt IPM strategies and can lead to secondary pest outbreaks.  A possible alternative to foliar applications of insecticides in fruiting vegetables is soil-applied systemic insecticides, which can be chemigated through the drip irrigation line.  Using a plant uptake bioassay in the lab, we evaluated the toxicity of four neonicotinoid insecticides, imidacloprid, dinotefuran, thiamethoxam and clothianidin on BMSB.  Preliminary data revealed an LC₅₀ value of ~ 0.01 ppm for clothianidin, dinotefuran and imidacloprid, and about 0.1 ppm for thiamethoxam when these chemicals were applied systemically to bean plants.  In addition, field efficacy experiments with the aforementioned insecticides were conducted on bell peppers planted near Blacksburg, VA in 2012.  Two soil applications were made about 30 days apart (one in June, one in July).   When applied to the soil at the base of plants, all four neonicotinoids,  imidacloprid, dinotefuran, thiamethoxam and clothianidin provided residual control of BMSB for up to 14 days and significantly reduced the percentage of damaged fruit at harvest when compared to an untreated control.  Additionally, imidacloprid and dinotefuran appeared to have the highest efficacy among the neonicotinoids.  Data for all aspects of this project will continue to be collected through the 2013 season.