PHYSIOLOGICAL ECOLOGY Development of Spalangia cameroni and Muscidifurax raptor (Hymenoptera: Pteromalidae) on Live House Fly (Diptera: Muscidae) Pupae and Pupae Killed by Heat Shock, Irradiation, and Cold

The objective of this study was to evaluate the suitability of killed house ßy (Musca domestica L) pupae for production of two economically important pupal parasitoids. Two-day-old ßy pupae were subjected to heat shock treatments of varying temperatures and durations in an oven at 70%RH; exposure to temperatures of 55 Cor higher for 15min or longer resulted in 100%mortality. Exposure to 50 C resulted in 40 and 91% mortality at 15 and 60 min, respectively. All (100%) pupae placed in a 80 C freezer were killed after 10-min exposure; exposure times of 5 min resulted in 21% mortality. Progeny production of Spalangia cameroni Perkins and Muscidifurax raptor Girault andSanders (Hymeoptera:Pteromalidae) frompupaekilledbyheat shockor50kRofgammaradiation was not signiÞcantly different from production on live hosts on the day when pupae were killed. Freeze-killed pupae produced 16% fewer S. cameroni than live pupae and an equivalent amount ofM. raptor progeny on the day when pupae were killed. When killed pupae were stored in freezer bags at 4 C for 4 mo, heat-killed, irradiated, and freeze-killed pupae remained as effective for production of M. raptor as live pupae. Production of S. cameroni on heat-killed and irradiated pupae was equal toparasitoidproductionon livepupae forup to 2moof storage, afterwhichproductiononkilledpupae declined to 63% of that observed with live pupae. Production of S. cameroni on freeze-killed pupae was 73Ð78% of production using live pupae during weeks 2Ð8 of storage and declined to 41 and 28% after 3 and 4 mo, respectively. Killing pupae by heat shock provides a simple and low-cost method for stockpiling high-quality hosts for mass-rearing both of these Þlth ßy biological control agents.