Oral treatment of rodents with ivermectin for the control of Phlebotomus papatasi (Diptera: Psychodidae) under laboratory conditions

The macrocyclic lactone ivermectin was evaluated as a rodent systemic and feed-through insecticide for control of adult and immature sand flies (Phlebotomus papatasi Scopoli). Syrian hamsters were fed diets containing 0 or 20 mg/kg ivermectin for 9 days, and sand flies were allowed to take bloodmeals from the hamsters 0, 3, 7, and 14 days after they were withdrawn from their diets. Ivermectin treatment of hamsters was 100% effective against bloodfeeding sand flies for up to 7 days after hamsters were withdrawn from ivermectin-treated diets. The survival and fecundity of sand flies that took bloodmeals from hamsters 14 days after they had been withdrawn from their ivermectin-treated diets were not significantly different from sand flies that took bloodmeals from control hamsters. Feces of the hamsters were collected 0, 3, 7, and 14 days after the hamsters had been withdrawn from their diets, and the feces were fed to 2nd instars of P. papatasi. All larvae that were fed feces of ivermectin-treated hamsters voided 0 days after being withdrawn from their diets died before pupation; larvae fed feces voided by ivermectin-treated hamsters 3 and 7 days after being withdrawn from their treated diets had significantly reduced survival. The results of this study suggest that oral ivermectin treatment of rodents could control immature and adult female sand flies that are closely associated with rodents.