House Fly Resistance to Organophosphorus Compounds in Arizona and Georgia

Abstract

Studies of Musca domestica taken from dairy or chicken farms in Savannah, Georgia (Anderson strain) and Phoenix, Arizona (Sharp strain) have shown the species to be highly resistant to malathion and, to a lesser degree, resistant to Diazinon and parathion. The ineffectiveness of malathion or Diazinon as field treatments against these strains was substantiated by laboratory tests. Dosages of 0.5 fig of malathlon/fly applied topically to susceptible CSMA flies produced 100% mortalities, whereas 66 to 72 ug of malathion/fly was required to give 100% mortalities of the Anderson and Sharp strains. The Sharp strain required approximately 10 times the dosage of Diazinon or parathion to produce 100% mortalities as compared with the CSMA susceptible strain.