DEVELOPMENT MODELS FOR THE FILTH FLY PARASITOIDS SPALANGIA-GEMINA, SPALANGIA-CAMERONI, AND MUSCIDIFURAX-RAPTOR (HYMENOPTERA, PTEROMALIDAE) UNDER CONSTANT AND VARIABLE TEMPERATURES

Development rates were determined for three pteromalid parasitoids of houseflies under constant and varying temperatures from 15 to 35 degre es C. Muscidifurax raptor Girault and Sanders was the fastest developi ng species, with females completing development in 13.8 days at 32.5 d egrees C and 66.5 days at 1.5 degrees C. Spalangia gemina Boucek femal es completed development in 20.8 days at 30.0 degrees C and 161 days a t 15.0 degrees C, whereas S. cameroni Perkins females completed develo pment in 20.6 days at 30.0 degrees C and 155.5 days at 15.0 degrees C. Male development times were 90.3% of those for female S. gemina and 9 2.7 and 88.6% of those for female S. cameroni and M. raptor, respectiv ely. Parasitoid survival was very low at 35 degrees C for all species and no Spalangia survived constant exposure to 15.0 degrees C. Exposur e to these lethal temperatures for shorter periods indicated that the parasitoids can tolerate them well under conditions more typical of th e held. Development rates were modeled using biophysical and degree-da y models and the models were tested for their ability to predict devel opment under fluctuating conditions (24-36 degrees C). Neither model w as superior for all three species because of interspecific differences in the parasitoids' responses to high temperatures. Agreement between predicted and observed development times for all three species was ac hieved by small empirical adjustments of a key parameter in the biophy sical model. (C) 1997 Academic Press.