Filth Fly Parasitoids Reared on Artificial Diets
Filth fly parasitoids are offered commercially by numerous suppliers, with report of both successes and failures in their ability to control flies. Some problems associated with the effectiveness of parasitoid releases include the quality of released parasitoids, the high release rates necessary to achieve major fly reduction and the economic feasibility of this method. It has long been theorized that artificial diets and improved rearing techniques could improve augmentative releases by lowering the cost.
The pupal fly parasitoid Muscidifurax zaraptor was reared on seven artificial diets composed of different amounts (0, 25, and 50%) of a house fly pupal extract, 25% fresh chicken egg yolk, and 25% powdered milk solution. Then a previously tested diet (25% of pupal extract) was compared with three other diets in which either the egg yolk or milk or both were removed. These four diets were tested with either house fly extract or a nonhost insect extract (derived from Heliothis virescens pupae).
There were no significant differences in the rates of development to adult in the diets with 50 or 25% pupaI extract. Almost no adults emerged from diets without insect extracts. Egg yolk significantly improved the yield of adults, while the addition of milk was not beneficial. Similar results were obtained with the H. virescens pupal extract, indicating that insect material from a nonhost source is suitable for the development of M. zaraptor.
The emerged adults mated and parasitized house fly pupae, producing viable offspring. The developmental time from egg to adult was slightly longer on the artificial diets than reported when reared in house fly pupae. The highest yields of parasitoid adults from diets with insect material is probably because of a better nutritional balance rather than special "host factors" from the insect extracts. However, even the best medium in these experiments would not be economically feasible for commercial rearing.
Fanti, P. and S. B. Vinson. 2000. In vitro rearing of Muscidifurax zaraptor (Hymenoptera : Pteromalidae) on artificial diets with and devoid of insect material. Biol. Control 18(1):49-54.
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