The Variation in the Sensitivity of Acetylcholinesterase in House Fly(Musca domestica) from Different Areas in Tianjin

Objective To determine the resistance of the field Musca domestica from different areas in Tianjin to DDVP and propoxur and to study the relationship between the bioassay resistance and the variation in sensitivity of acetylcholinesterase(AChE).Methods The resistant levels to DDVP and propoxur of field M.domestica from different areas in Tianjin was tested using topical application method.The sensitivity variation of AChE for both field resistant strains and lab relatively sensitive strain were compared.Results All the 7 field populations were found to have developed resistance to DDVP and propoxur.Compared with the lab relatively sensitive strain,the K_m value altered slightly.The V_(max) value rose significantly,(6.24) times as that of the lab relatively sensitive strain at most.The sensitivity of the AChE to DDVP and propoxur declined significantly with a rising in the medium inhibitory concentration(I_(50)) by 15 times at most.Conclusion The insensitivity of AChE of field Musca domestica in Tianjin is possibly responsible for the resistances to DDVP and propoxur.