Non-target effects of three insecticides on the natural enemy community of sorghum aphid in grain sorghum

Pyrethroid-based insecticides are among the most widely used control tactics for rice stink bug in grain sorghum in the Coastal Bend of Texas. In a 2021 study, we documented pyrethroid resistance in rice stink bug, Oebalus pugnax (F.), in populations collected from the Coastal Bend using a glass vial bioassay with residues of a pyrethroid, lambda-cyhalothrin. To evaluate the efficacy of other insecticides which could serve as alternatives, we conducted field experiments in grain sorghum plots with three commercial insecticides from different classes during the summer of 2023. The insecticides we evaluated were lambda-cyhalothrin, dimethoate, and dinotefuran. Dimethoate, which was recently labeled for use on stink bugs in grain sorghum, and dinotefuran, which is not labeled for use in grain sorghum, are known to be broad-spectrum and disruptive to beneficial insects that can suppress pest populations. Currently, research is limited on the non-target effects of these insecticides on natural enemies in grain sorghum. Understanding the non-target effects of these insecticides in a grain sorghum system is essential to developing a successful integrated pest management program. To accomplish this, we collected data on the natural enemy community composition of sorghum aphid, Melanaphis sorghi (Theobald), an important pest of grain sorghum, as well as the pest itself. We conducted surveys to collect data on natural enemies and sorghum aphid populations before and after insecticide treatments. Data gathered will be used to inform management practices.