Modeling Host Attacks and Progeny Production ofSpalangia gemina, Spalangia cameroni,andMuscidifurax raptor(Hymenoptera: Pteromalidae) at Constant and Variable Temperatures

In assays at constant temperatures,Spalangia geminaBoucek,Spalangia cameroniPerkins, andMuscidifurax raptorGirault and Sanders females killed more house fly (Musca domesticaL.) pupae at 30°C than at 15, 20, 25, or 35°C, with attack rates for the three species of 11.2, 12.6, and 21.1 pupae killed per parasitoid per day, respectively. Progeny production followed a similar pattern, with maximum rates of 6.8, 7.5, and 9.2 progeny per day at 30°C forS. gemina, S. cameroni,andM. raptor,respectively. BothSpalangiaspecies produced proportionally fewer males at higher temperatures than at lower temperatures; sex allocation byM. raptorwas relatively unaffected by temperature except for a trend to produce fewer females at 15°C (29.6% females) than at higher temperatures (43–47%). The four-parameter thermodynamic model of Sharpe and DeMichele with high temperature inhibition fit the attack rate and progeny production rate data well. These models were very effective at predicting host attacks and parasitism at high, variable temperatures typical of outdoor mid summer conditions in many regions, provided that 1-h time steps were used in rate summation algorithms. Assays for long-term net rates of fly destruction revealed thatS. geminaandS. cameroniwould be most effective for fly control at 25°C and substantially less effective at either low (15°C) or high (35°C) temperatures.M. raptorwas equally effective at killing house fly pupae over the 15–30°C range, but was significantly less effective at 35°C.