Thermal death kinetics of pests in tobacco leaves as influenced by heating rates and life stages

Abstract

Thermal death kinetics of insects are essential for developing effective disinfestation protocols using heating treatments. The thermal resistance of Lasioderma serricorne (F.) (Coleoptera: Anobiidae) and Ephestia elutella (Hübner) (Lepidoptera: Pyralidae) under different life stages were compared using a heating block system (HBS) and the more resistant pest and life stage were selected for further establishing the thermal death kinetic model at four temperatures under a specified heating rate. The results indicated that when the two target pests were in the same life stage, the tobacco beetle was more heat-tolerant than the tobacco moth and selected for the following thermal death kinetic studies. With the stronger heat tolerance than that of adults and eggs, the mortality rate of tobacco beetle larvae was determined as influenced by the 5 heating rates, showing that the heating rate of 5 °C/min resulted in higher mortality as compared to 0.1 or 0.5 °C/min and similar mortality to 1 and 10 °C/min, and selected for further studies to effectively simulate rapid radio frequency heating. The 0th-order kinetic response model was more suitable for describing thermal death curves of L. serricorne larvae. The minimum holding time required to kill all the test pests was 48, 28, 8, and 2 min at 51, 53, 55, and 57 °C, respectively. The activation energy required to eliminate L. serricorne was calculated to be 553.8 kJ/mol. The information gained from this study is instrumental in designing efficient heat treatment protocols for disinfesting tobacco leaves.