Pesticide Biochemistry and Physiology

CYP6D1 is the cytochrome P450 responsible for pyrethroid resistance in the LPR strain of house fly, which was originally collected from New York and was recently implicated as a mechanism of resistance in house flies from Georgia. We sequenced CYP6D1 from the NG98 strain of house fly from Georgia and found that the CYP6D1 allele in this strain is identical to that found in the LPR strain (CYP6D1v1). This is in contrast to the other five alleles of CYP6D1 from pyrethroid-susceptible strains which were all unique (i.e., different from all other strains). These results indicate that CYP6D1-mediated resistance may have evolved once and then spread between these two states. This is unexpected as house flies are not documented to disperse over long distances. The finding of identical alleles in the pyrethroid-resistant NG98 and LPR strains supports the hypothesis that the different CYP6D1 protein in resistant strains contributes to their resistance. q 2002 Elsevier Science (USA)