Abstract: Culex pipiens quinquefasciatus sampled in Guangzhou in China, has larval resistance to organophosphate insecticides. The results of starch gel electrophoresis and Southern hybridization indicate that there are seven highly active esterases:esterase β11，α2/β2，α6/β6 and α8/β8 in this population. A new esterase haplotype(esterase α8/β8) was found in the populations. The results of the migration rate and RFLP polymorphism of these highly active esterases indicate the esterase α8/β8 is different from the others. In the same way,Culex pipiens quinquefasciatus populations sampled from Wuhan and Shashi in China, were analyzed. Also a new pair of esterase α8/β8 are involved in Wuhan and Shashi populations.

Key words: mosquitoes, organophosphate resistance, RFLP, amplification Author for correspondence