Abstract
A comparison was made between the CSMA, Takatsuki and RP strains, the last has developed organophosphorus resistance in Switzerland. The LD_<50> value to diazinon topically applied to female RP flies was about 10 times that of the CSMA and Takatsuki, respectively. The ratio of the LD_<50> of RP flies to that of regular flies was 4.4-19.8 for γ-BHC, 24.8-34.4 for dieldrin, and 3.2-65.4 for technical DDT. Tests using the third instar larvae of the RP strain indicated the larval LC_<50> level to be 13 times the normal larvae for diazinon.
