The resistant level of the houseflies to several synthetic insecticides in the Philippines

Abstract

The resistance level of the 15 strains of houseflies collected from the Philippines were examined against 6 insecticides, DDT, pyrethrins, malathion, fenitrothion, fenthion, and dichlorvos. Most colonies showed higher susceptibility against these insecticides than the Takatsuki strain, especially to DDT. The LD_<50> values of malathion were between 0.0975μg per fly. Among the 15 strains, 7 showed higher LD_<50> values against malathion than the Takatsuki strain. These results mean that the houseflies in the Philippines are increasing their resistance against malathion.