An acetylcholinesterase gene, acel, has been cloned and sequenced from both susceptible and field strains of Culex pipiens pallens. Comparison of both nucleic acid and deduced amino acid sequences revealed an amino acid substitution. The mutation A328S corresponding to A201S in Torpedo californica abutting the oxyanion hole of AChE1, might affect the stability of enzyme-substrate transition state and result in insecticide resistance. The mutation had been found in seven field strains of Cx. pipiens pallens collected in Beijing, China, and also had been detected in the Labagoumen strain by PCR-restriction endonuclease assay during 2003–2005. We suggested that A201S replacement in the acel gene is possibly responsible for insensitivity of AChE1 to some carbamates or organophosphates in field strains of mosquitoes.
Culex pipiens pallens