Thermal death kinetics and heating rate effects for fifth-instar Cydia pomonella (L.) (Lepidoptera: Tortricidae)

Thermal death kinetic parameters of fifth-instar codling moths (Cydia pomonella (L.)) and the effect of three heating rates (1degreesC min(-1), 10degreesC min(-1), and 18degreesC min(-1)) on larval mortality were determined by a heating block system. The insects were heated to four temperatures (46degreesC, 48degreesC, 50degreesC, and 52degreesC) held for predetermined periods followed by 24 h storage at 4degreesC before mortality evaluation. Thermal death kinetics for fifth-instar codling moths followed a 0.5th order of kinetic reaction. Minimum time required to achieve 100% mortality of a given population decreased with temperature in a semi-logarithmic manner. No larval survival was observed in samples of 600 insects after exposure to 46degreesC, 48degreesC, 50degreesC, and 52degreesC for 50, 15, 5, and 2 min, respectively. Activation energy for thermal kill of fifth-instar codling moths at the heating rate of 18degreesC min(-1) was estimated to be about 472 kJ mol(-1). The lethal time accumulated during the ramp period was about 1.8, 0.2, and 0.1 min for the heating rates of 1degreesC min(-1), 10degreesC min(-1), and 18degreesC min(-1), respectively. (C) 2002 Elsevier Science Ltd. All rights reserved.