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 detection of the point mutations of the kdr gene at codon 1014 was conducted by PCR and DNA sequencing in the deltamethrin-resistant 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 different mortalities were observed among populations for the remained three insecticides tested (deltamethrin, malathion, and bendiocarb) (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 resistance 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.
［摘要］目的 了解安徽省中北部地区淡色库蚊对多种杀虫剂的抗药性现状及其kdr 基因突变情况。方法 2014年 6–9月在淮北市、蚌埠市和滁州市3地采集淡色库蚊幼虫, 带回实验室饲养至成虫, 采用WHO成蚊接触筒药膜滤纸接触 法对其进行0.05%溴氰菊酯、5%马拉硫磷、0.1%噁虫威、4%DDT抗性生物测定。以PCR扩增经溴氰菊酯抗性测定的库蚊 抗性相关kdr 基因并进行测序, 统计L1014位点突变情况。结果 上述3个地区淡色库蚊对溴氰菊酯、马拉硫磷、噁虫 威、DDT 4种杀虫剂都产生了不同程度的抗药性, 对DDT产生的抗性较高; 虽然3地淡色库蚊接触DDT后的死亡率差异 无统计学意义 (F = 1.027, P > 0.05); 但接触溴氰菊酯、马拉硫磷、噁虫威后的死亡率差异均有统计学意义 (F = 23.823、 33.955、128.841, P 均< 0.01) 。3地淡色库蚊种群的kdr 基因1014位点均存在L1014F、L1014S 这2种非同义突变; L1014F 突变频率与溴氰菊酯抗性水平呈正相关 (r2 = 0.718, P < 0.01) 。结论 安徽省中北部地区淡色库蚊对溴氰菊酯、马拉硫 磷、噁虫威、DDT均产生了较强的抗性, kdr 基因L1014F突变频率与溴氰菊酯抗性水平呈正相关; 各地区卫生部门需加强 对媒介蚊虫抗性的动态监测。.
Keywords: Anhui Province; Bendiocarb; Cluex pipiens pallens; DDT; Deltamethrin; Insecticide resistance; Kdr mutation; Malathion.