Multiple insecticide resistances and kdr mutation of Culex pipiens pallens in north-central Anhui Province / 中国血吸虫病防治杂志

ABSTRACT

Objective To understand the status of resistance to multiple insecticides and the frequencies of kdr mutations in Culex pipiens pallens from north?central Anhui Province. Methods From July to September,2014,the C. pipiens pallens mosquito larvae were collected in Huaibei,Bengbu and Chuzhou cities of the north?central Anhui Province and reared to adults. The female adult mosquitoes at 3-5 days post emergence were tested for susceptibility to the four insecticides,namely 0.05%deltamethrin,5%malathion,0.1%bendiocarb and 4%DDT,by using the standard WHO resistance tube bioassay. The detec?tion of the point mutations of the kdr gene at codon 1014 was conducted by PCR and DNA sequencing in the deltamethrin?resis?tant and?susceptible mosquitoes. Results High levels of resistance to all the four insecticides were found in all the three tested populations,although mosquito mortality varied among populations and test insecticides. Among the test insecticides,DDT showed lowest mortality with no significant difference(F=1.027,P>0.05)in all test populations,whereas significantly differ?ent mortalities were observed among populations for the remained three insecticides tested(deltamethrin,malathion,and ben?diocarb)(F = 23.823,33.955,128.841;all P < 0.01). Two types of non?synonymous kdr mutation at codon position 1014 (L1014F and L1014S)were observed. A positive correlation between L1014F mutation frequencies and deltamethrin resistance levels were detected in the three mosquito populations(r2=0.718,P<0.01). Conclusions The observed high levels of resis?tance to multiple?insecticides coupled with the occurrence of medium to high kdr frequencies in populations of C. pipiens pallens could profoundly affect the mosquito vector control programme in China. The local health departments need to strengthen vector dynamic monitoring and implement rational resistance management strategies.