Heat-induced mortality and expression of heat shock proteins in Colorado potato beetles treated with imidacloprid

Temperature, which is a major abiotic factor for ectotherms, plays a vital part in physiology and biochemistry of insects. Heat shock protein is a highly conservative subset of molecular chaperones that is in charge of transport, folding, unfolding, assembly, and disassembly of multi-structured protein units and degradation of misfolded or aggregated proteins. Previous studies have also indicated that temperature stress may be more detrimental for insects treated with insecticides. In our study, thermotolerance at 43 ºC was similar for different geographical strains on Colorado potato beetle, Leptinotarsa decemlineata (Say). Imidacloprid applications reduced expression of the Hsp70 heat shock protein at both optimal and extreme temperatures. Our study indicates that exposure to the heat shock was more detrimental to the survivorship of the imidacloprid-treated larvae. Even before the heat treatment, imidacloprid already started to suppress the induction of heat shock protein.