Insecticide resistance and kdr，ace-1 allele mutations of Anopheles sinensis in Chongming District， Shanghai

Objective To investigate the resistance to pyrethroids， beta-cyhalothrin and fenitrothion as well as the frequencies of kdr and ace⁃1 alleles in Anopheles sinensis from three geographical populations in Chongming District， Shanghai.

Methods The contact tube method recommended by WHO was used to determine mosquito resistance. The frequencies of kdr and ace⁃1 alleles in adult mosquitoes were determined by PCR amplification. The correlation between the frequencies of kdr alleles and insecticide resistance was analyzed by linear regression method.

Results The mosquito population near natural reserve （NF） was sensitive to deltamethrin， and the mortality rate was 100.00% at 24 h. The mosquito population with intensive breeding farms （HX） showed resistance to deltamethrin and beta-cyhalothrin， and the 24 h mortality was 48.00 % and 57.50 %， respectively. The 24 h mortality rate of the mosquito population with urban-rural integration area （AS） with suspected resistance to deltamethrin and beta-cyhalothrin was 84.40% and 86.00%. The 24 h mortality rate to Fenitrothion was 55.67%. There were 3 mutations in kdr gene locus 1014， and 7 mutated genotypes were detected， mainly L1014/L1014F and L1014F/L1014F. The mutation frequency of kdr allele in HX population was the highest （52.68%）. There was one mutation at site 119 of ace⁃1 gene， and three genotypes were detected， most of which were G119S mutation. There was a significant negative correlation between the frequency of kdr resistance allele and the mortality rate of beta-cypermethrin in An.sinensis populations （r²=0.930，P=0.036）. There was a significant negative correlation between the frequency of ace⁃1 resistance allele and the mortality rate of fenitrothion in An. sinensis populations from four habitats （r²=0.996，P=0.038）.

Conclusion The mutation frequency of insecticide resistance allele is associated with the development of mosquito resistance level. Therefore， comprehensive monitoring of resistance levels of An.sinensis in Chongming area should be continued to provide a basis for local mosquito resistance management.