Thermal conditioning of fifth-instar Cydia pomonella (Lepidoptera: Tortricidae) affects HSP70 accumulation and insect mortality

Levels of HSP70 protein of fifth-instar codling moth [Cydia pomonella (L.) (Lepidoptera: Tortricidae)] are determined after conditioning at 35 C for different times and also after recovery at 22 C. Protein samples from larvae conditioned for different times are separated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis electrophoresis. Sub-lethal thermal conditioning at 35 C for 40 min, 2, 6 and 18 h induces new protein bands in the extracts from treated codling moth larvae. Immunodetection with an antibody to a heat-inducible HSP70 indicates a stronger reaction after 35 C for 2, 6 and 18 h than after 35 C for 40 min or control and, during the recovery period at 22 C, the level of heat shock protein decreases. Conditioning of fifth-instar codling moths at 35 C also induces thermotolerance in the insects and necessitates longer times at a lethal temperature to ensure mortality. Thermotolerance is correlated with the accumulation of heat inducible HSP70 protein.