Abstract:Objective To investigate the deltamethrin resistance in Culex pipiens pallens and the association with the knockdown resistance mutation and to explore the establishment of mosquito resistance testing method. Methods Kdr gene sequences was isolated from different parts of wild Culex pipiens pallens mosquitoes using specific primers by RT-PCR and AS-PCR technique,and sequenced. Using the linear regression analysis to determine the relationship between the mutation and deltamethrin resistance. Results Knockdown resistance allelic gene was cloned and sequenced. Analysis of DNA sequences revealed the presence of two point mutations at L1014 residue in the IIS6 transmembrane segment of vgsc, i.e., L1014F TTA mutaions as TTT, the corresponding leucine ( L ) by phenylalanine ( F ) replaced; L1014S;TTA mutaions as TCA, the corresponding leucine ( L ) ( S ) replaced by serine. Two alternative kdr-like mutations, L1014F and L1014S, was positively related to deltamethrin resistant phenotype.The results are basically the same by RT-PCR and AS-PCR technique in mosquito restance.Conclusion Two alternative kdr-like mutations in Culex pipiens pallens was positively related to deltamethrin resistant phenotype. Further studies are needed to determine the specific resistance mechanism. RT-PCR and AS-PCR technique can be applied to the mosquito resistance field test.