Thermal death kinetics of fifth-instar Corcyras cephalonica (Lepidoptera: Galleriidae)

The infestation of rice moth, Corcyras cephalonica (Lepidoptera: Galleriidae), causes severe losses in postharvest walnuts. Heat has been studied as a phytosanitary treatment to replace chemical fumigation for controlling this pest. Information on kinetics for thermal mortality of C. cephalonica is needed for developing effective postharvest phytosanitary thermal treatments of walnuts. Thermal death kinetics of fifth-instar C. cephalonica were investigated at temperatures between 44°C and 50°C at a heating rate of 5°C min(-1) using a heating block system. The results showed that thermal-death curves for C. cephalonica larvae followed a 0 order of kinetic reaction. The time to reach 100% mortality decreased with increasing temperature from 150 min at 44°C to 2.5 min at 50°C. The activation energy for controlling C. cephalonica was 466-592 kJ/mol, and the z value obtained from the thermal death time curve was 3.3°C. This kinetic model prediction could be useful in designing the thermal treatment protocol for controlling C. cephalonica in walnuts.