Kinetics of Thermal Death in Eggs and First Instars of Three Species of Fruit Flies (Diptera: Tephritidae)

Abstract

Kinetics of thermal death and death rate curves for eggs and first instar Mediterranean fruit fly, Ceratitis capitata (Wiedemann); oriental fruit fly, Dacus dorsalis (Hendel); and melon fly, Dacus cucurbitae (Coquillett), were determined at temperatures between 42 and 48°C and for times of up to 50 min using a hot water-immersion technique. Both eggs and larvae of all three species showed mortality that was directly related to the severity of treatment and time of exposure. Larvae appeared more resistant to heat than eggs at a given temperature. Larval tolerance to heat was very similar for all species; Mediterranean fruit fly eggs appeared more tolerant to heat than those of either of the Dacus species. Eggs and larvae of all three species showed death rate curves characterized by a lag at lower temperatures followed by a more or less constant rate of death. At high temperatures, the curves appeared logarithmic. This information may be useful in determining suitability of heat treatments for disinfestation of commodities attacked by these insects.