In vitro rearing of Muscidifurax zaraptor (Hymenoptera : Pteromalidae) on artificial diets with and devoid of insect material

We present the first report on in vitro rearing of Muscidifurax zaraptor Ko gan and Legner, a pupal parasitoid of Musca domestica L. and other muscoid flies. We first tested seven artificial diets composed of different amounts (0, 25, and 50%) of a Mu. domestica pupal extract, 25% fresh chicken egg y olk, and 25% powdered milli solution. Then we compared one of the previousl y tested diets (25% of pupal extract) with three other diets in which eithe r the egg yolk or milk or both were removed. We tested these four diets usi ng insect material either from Mu. domestica or a nonhost insect source, wh ich was Heliothis virescens (F.). We observed no significant differences in the rates of development to adult in the diets with 50 or 25% pupaI extrac t. Almost no adults emerged from two diets without insect material, but in a third one about 8% of parasitoids completed development. Egg yolk signifi cantly improved the yield of adults, while the addition of milli was not be neficial. Using the H. virescens pupal extract similar results were observe d, indicating that insect material from a nonhost source is suitable for th e development of M. zaraptor: The emerged adults mated and parasitized hous e fly pupae, producing viable offspring. The developmental time in vitro fr om egg to adult was slightly longer than that reported in vivo. The results we observed suggest that the highest yields of parasitoid adults from diet s with insect material can be explained in terms of a better nutritional ba lance rather than advocating "host factors." (C) 2000 Academic Press.