New esterase enzymes involved in organophosphate resistance in Culex pipiens (Diptera : Culicidae) from Guang Zhou, China

Organophosphate (OP) insecticides have been used widely to control Culex pi piens L. populations and this has led to the emergence of OF-resistance. Pr edominantly, resistance in Cx. pipiens is caused by over-production of nons pecific esterases, such as Est beta 1(1) and Est alpha 2(1)/beta 2(1). Thes e esterases confer multiple resistance to organophosphorus and carbamate in secticides. To define the esterases in Chinese Cx. pipiens, restriction fra gment-length polymorphism analysis was performed at the esterase beta locus . A new esterase haplotype (Est beta 8) was found. Starch gel electrophores is indicated that Est beta 8 was coelevated with a novel Est alpha 8. This article reports Est alpha 8/beta 8 esterase-mediated resistance in Cx. pipi ens complex.