Determination of Malathion and Diazinon Resistance by Sequencing the MdαE7 Gene from Guatemala, Colombia, Manhattan, and Thailand Housefly (Musca domestica L.) Strains

Organophosphate (OP) insecticides (parathion/diazinon) resistance in housefly (Musca domestica L.) is associated with the change in carboxylesterase activity. The product of αE7 gene, which is a member of α-esterase gene cluster, is probably playing a role in detoxyfication of the xenobiotic esters. In parathion/diazinon resistant M. domestica species Gly137 to Asp substitution was found in the active center of the product of αE7 gene. In malathion (an OP) resistant M. domestica strains Trp251 to Ser substitution was identified in the active center of the MdαE7. In our research, to understand the allelic diversity of the MdαE7, the gene was partially sequenced from four different housefly strains from different localities (Guatemala, Manhattan (USA), Colombia (USA), and Thailand). It was found out that; in Thailand strain one allele has Cys residue at the position of 251, the other allele contains a Trp for the same site. In Colombia strain, one allele has Asp137, the other allele contains a Gly residue at this point. The Manhattan and Guatemala strains have Asp137 and Trp251 residues on their both alleles at these two different positions.