RESISTANT LEVEL OF HOUSEFLIES TO SEVEN KINDS OF SYNTHETIC INSECTICIDES AND EFFECT OF SYNERGISTS TO THE MALATHION RESISTANT STRAIN IN SINGAPORE

Abstract

The resistant level of the houseflies to the seven kinds of insecticides, Malathion, Sumithion, Baytex, Diazinon, DDVP, DDT and Chrysron, was examined on the 3 strains collected in Singapore. It was found that most housefly colonies in Singapore showed a higher susceptibility to those insecticides than that of the Takatsuki strain of Japan, especially to DDT. However, the resistant level to Malathion was remarkably higher than that of the Takatsuki strain. The synergists, piperonyl butoxide, Safroxane and S 421, mixed with Malathion were effective for lowering the resistant level of the Malathion-resistant strain.