Detection of organophosphate resistance in house flies population (Musca domestica L.) by laboratory bioassay method

House fly menace is one of the major problems in poultry industry in the recent years. High density of flies not only cause stress to birds and farmworkers, they can also cause great annoyance to nearby human habitations which poses a serious public health problem. Adult house flies were collected from five selected poultry farms using sweep net and reared in laboratory. Three to five days old F1 generation flies produced by the healthy parental population, maintained in the laboratory were used for topical and contact residual bioassays. In this study, different concentrations of dichlorvos were used for topical bioassay such as, 0.02, 0.04, 0.08, 0.1, 0.2, 0.4 and 0.8 µg (a.i)/µl and 0.14, 0.28, 0.56, 1.12, 2.24 and 4.48 µg (a.i)/cm2 for residual contact bioassay. Mild to moderate resistance was observed in F1 generation house flies treated with dichlorvos from all the five farms. The resistance ratio ranged between 1.46 to 15.15 and 6.23 to 22.45 fold by topical and residual contact bioassay respectively. In the present study to identify the level of insecticide resistance in house flies to common insecticides by laboratory bioassay methods.