Mortality and HSP Genes Expression in the Endoparasitoid Cotesia chilonis (Hymenoptera: Braconidae) After Cold Acclimation at Different Temperatures

Cotesia chilonis (Munakata) is an endoparasitoid wasp of Chilo suppressalis Walker (Lepidoptera: Pyralidea) larvae. Little is known regarding the tolerance of C. chilonis after cold acclimation at different temperatures. In this study, we investigated mortality and the molecular basis of temperature tolerance in C. chilonis reared under normal conditions (27 degrees C) and after cold acclimation at 4 degrees C for 5 d. We evaluated the relative expression of five genes encoding heat shock proteins (HSPs) in C. chilonis by RT-qPCR after cold acclimation and exposure to temperature stress.The results demonstrated that cold acclimation could significantly enhance the survival of C. chilonis adults under high temperatures, and expression of the five C. chilonis HSP genes had distinctly different expression patterns in response to temperatures. Cchsp40 and Cchsp90 had similar expression pattern that upregulated significantly at -12 and 39 degrees C. Cchsp70 could be induced by high and low temperatures, whereas Cchsp60 and Cchsc70 showed no significant difference in expression when exposed to thermal stress. This study provides important biological information that may help extend the shelf life of C. chilonis, which is an important consideration in the use of this wasp as a biological control agent.