Cyromazine Resistance in the House Fly (Diptera: Muscidae)

Abstract

Tolerance to the new insect growth regulator (IGR) cyromazine was detected in a wild, organophosphate-resistant house fly, Musca domestica L., strain. Laboratory selection with cyromazine for 15 generations increased resistance 69.8-fold at the EC50 when compared with an insecticide-susceptible laboratory strain of flies. Cyromazine resistance decreased in the original resistant colony when it was reared for 15 generations without any new cyromazine exposure. No cross-resistance to the IGR methoprene was found in the cyromazine-resistant strain.