Thermal Death Kinetics of Egg and Third Instar Mediterranean Fruit Fly (Diptera: Tephritidae)

Abstract

Two developmental stages of Ceratitis capitata (Wiedemann), 24-h-old eggs and third instars, 8 d after oviposition, were subjected to thermal exposures in a heating block system, at various temperatures of 46, 48, 50, and 52 degrees C to determine the thermal death kinetics of the insects. At these temperatures, 100% mortality was achieved by exposure of 300 C. capitata larvae for 60, 15, 4, and 1 min, respectively. The 0.5 order kinetic model had the best fit to the survival ratio for all the treatment temperatures, hence it was used for the prediction of the lethal times. The thermal death time (TDT) curves showed that the third instars were more heat-resistant than eggs, especially at the two low temperatures (46 and 48 degrees C). Under temperature-time combinations that did not result in complete kill, the thermal mortality for eggs was also significantly higher than that for third instars. The activation energy values calculated from the TDT curves were 490.6 and 551.9 kJ/mol, respectively, for thermal death of eggs and third instars.