OBJECTIVETo investigate the heterozygous genotype and molecular characteristics of Organophosphorus resistance associated with heterozygous Estbeta2 of esterase B2 gene from natural population of Culex pipiens complex.

METHODSGenomic DNA was extracted from natural populations of Culex pipiens complex in Hangzhou. The PCR-restriction fragment length polymorphism (PCR-RFLP) assay was applied to type the resistance associated esterase gene. Estbeta2 of esterase B2 gene was identified by PCR-RFLP, and the genotyping for heterozygous Estbeta2 was carried out after restriction enzyme digesting by Bfm I endonuclease.

RESULTSThe DNA was isolated from 207 Culex pipiens respectively, while 156 PCR samples showed positive and the positive rate was 75.36% (156/207). The PCR-RFLP assay of esterase B2 gene revealed that the Estbeta2 was accounted about 28.20% (44/156) in 156 positive samples. There were two genotypes identified, namely homozygous Estbeta2 (90.90%, 30/33) and heterozygous Estbeta2 (9%, 3/33), heterozygous Estbeta2 was in existence of a hybrid form as which combined with Estbeta2 and a subtype (Estbeta2/Estbeta2(1)).

CONCLUSIONHeterozygous Estbeta2 of Organophosphorus resistance associated with esterase genotype was determined in natural population of Culex pipiens, and a genotyping method was established.