Determining the impact of sub-lethal environmental conditions in combination with different insecticides against bed bugs, Cimex lectularius

Different insecticides, such as pyrethroids, neonicotinoids, and pyrroles are used for bed bug management. Insecticides may be applied before or after a heat treatment to ensure that bed bugs finding refuge from elevated temperatures are also eliminated. However, insecticide efficacy can vary at elevated-temperature conditions. Therefore, the overall project goal of this study is to determine how insecticide toxicity is influenced at varied lethal environmental conditions against Harlan bed bug strain. LD₂₅ of three insecticides: bifenthrin, clothianidin, and chlorfenapyr, was applied to bed bugs and they were subsequently exposed for 48hours (bifenthrin and clothianidin) and 144 hours (chlorfenapyr) to elevated temperatures (38°C) at low (10% RH) and high (90% RH) humidity for 48 hours (bifenthrin and clothianidin) and 144 hours (chlorfenapyr). Results indicated a potentiative effect between lethal environmental conditions and the toxicity of clothianidin, whereas bifenthrin and chlorfenapyr showed antagonistic interactions with temperature and tested relative humidities. The results demonstrate that with environmental conditions can have negative or positive effect regarding the efficacy of insecticides against bed bugs. Therefore, choosing an appropriate insecticide to use in combination with heat treatments is an important factor when using both treatment types to eliminate bed bugs