Dose-Mortality Relationships for Eggs and Larvae of Bactrocera tryoni (Diptera: Tephritidae) Immersed in Hot Water

Heat dose-mortality relationships at 44, 45, 46, 47, and 48°C were determined for new (5% developed) and old (80% developed) eggs and first, second, and third instars of the Queensland fruit fly, Bactrocera tryoni (Froggatt). The most tolerant stages were mature eggs at the lower temperatures, and third instars at the higher temperatures. New eggs were the least tolerant stage at all temperatures. First and second instars were intermediate in their tolerance. Determination of heat disinfestation treatment efficacy should thus be directed against third instars or mature eggs (depending on the temperature). Predicted times to achieve probit 9 quarantine security at these temperatures for all stages are presented. This information may be used to determine heat disinfestation times with hot water and vapor heat for commodities subject to infestation by this insect.