|Year of Publication:
|K. D. Floate, Fox A. S.
|Bulletin of Entomological Research
Common house flies, Musca domesticaLinnaeus, were reared to pupation with exposure to ivermectin, washed, and then exposed to parasitism by Muscidifurax zaraptorKogan & Legner. Pupae exposed to ≥0.25 ppm ivermectin produced 63% fewer parasitoids than did control pupae. Pupae exposed to 0.01 ppm ivermectin produced 23% more parasitoids. Exposure to 0.10 ppm ivermectin had no detectable effect. Treatments did not affect the developmental time of male or female F 1parasitoids. Treatments did not affect the production of adult F2progeny by F 1 females, nor the sex ratios of these offspring. This study documents an indirect effect of ivermectin residues across trophic levels. It identifies altered host quality as another mechanism by which faecal residues of ivermectin may affect insect activity in dung of treated cattle. The importance of this phenomenon under field conditions is undetermined.