Thermal Death Kinetics of Conogethes Punctiferalis (Lepidoptera: Pyralidae) as Influenced by Heating Rate and Life Stage

lixia hou...[et al.];

Thermal death kinetics of Conogethes punctiferalis (Guene�e) (Lepidoptera: Pyralidae) at different life stages, heating rate, and temperature is essential for developing postharvest treatments to control pests in chestnuts. Using a heating block system (HBS), the most heat-tolerant life stage of C. punctiferalis and the effects of heating rate (0.1, 0.5, 1, 5, and 10C/min) on insect mortality were determined. The thermal death kinetic data of fifth-instar C. punctiferalis were obtained at temperatures between 44 and 50C at a heating rate of 5C/min. The results showed that the relative heat tolerance of C. punctiferalis was found to be fifth instars>pupae> third instars> eggs. To avoid the enhanced thermal
tolerance of C. punctiferalis at low heating rates (0.1 or 0.5C/min), a high heating rate of 5C/min was selected to simulate the fast radio frequency heating in chestnuts and further determine the thermal death kinetic data. Thermal death curves of C. punctiferalis followed a 0th-order kinetic reaction model.
The minimum exposure time to achieve 100% mortality was 55, 12, 6, and 3 min at 44, 46, 48, and 50C, respectively. The activation energy for controlling C. unctiferalis was 482.15 kJ/mol with the z value of 4.09C obtained from the thermal death�time curve. The information provided by thermal death kinetics
for C. punctiferalis is useful in developing effective postharvest thermal treatment protocols for disinfesting chestnuts