Study on kdr allele mutation of Culex pipiens pallens in Zichuan District, Zibo City, Shandong Province

Abstract

Objective To study the seasonal dynamics of Culex pipiens pallens and the distribution of knockdown resistance ( kdr) gene related sodium channel gene polymorphism in Zichuan District, Zibo City, Shandong Province.

Methods Cx. pipiens pallens mosquitoes were collected in Zichuan District during the peak period of mosquito vector activity from 2017 to 2018. The DNA from Cx. pipiens pallens was extracted, and the genotypes and frequencies of kdr allele mutation were detected by polymerase chain reaction.

Results Totally 830 mosquitoes belonging to six species, including Cx. pipiens pallens, Armigeres subalbatus, Aedes albopictus, Ae. vexans, Anopheles sinensis, and Cx. tritaeniorhchus were collected in this study. The number of Cx. pipiens pallens accounted for 83.13% in total, with the density of 12.32 per lamp per night. The annual density monitoring curve of Cx. pipiens pallens showed a bimodal trend, and the peaks were observed in June and September respectively. In this study, five kdr alleles were detected at the 1 014 locus of kdr gene, with TTA (75.71%), TTT (10.00%), CTA (5.71%), TCA (4.29%), and TTC (4.29%). Two nonsynonymous nucleotide mutations were detected at site 1 014 of kdr gene, namely leucine (L1014) mutated to phenylalanine (L1014F) and serine (L1014S). The kdr gene mutation frequency (%) of Cx. pipiens pallens in Luochun Town and Taihe Town was 10.53% and 40.63%, respectively, and the difference was statistically significant ( χ ² = 8.559, P = 0.003).

Conclusion Cx. pipiens pallens is the dominant mosquito species in Zichuan District. In addition, two novel mutations, CTA and TTC, are identified in the voltage-dependent sodium channel gene of Cx. pipiens pallens. The kdr genotype of Cx. pipiens pallens in Zichuan area was polymorphic.

Abstract

[ 摘要] 目的 了解山东省淄博市淄川区淡色库蚊 ( Culex pipiens pallens) 季节消长趋势及蚊虫击倒抗性 (Knockdown resistance, kdr) 相关钠通道基因多态性分布特征。 方法 于 2017–2018 年蚊媒活动高峰期, 使用诱蚊灯法对山东省淄博市 淄川区进行蚊虫种群和密度调查, 提取淡色库蚊 DNA, 通过 PCR 检测 kdr 等位基因突变类型和频率。 结果 在山东省淄 博市淄川区共捕获 830 只蚊虫, 包括淡色库蚊、骚扰阿蚊、白纹伊蚊、刺扰伊蚊、中华按蚊和三带喙库蚊 6 种, 其中淡色库 蚊占 83.13%, 密度为 12.32 只/(台·夜) ; 淡色库蚊全年密度监测曲线呈双峰 趋 势, 高 峰 出 现 在 6 月 和 9 月。在 kdr 基因 1 014 位 点 共 检 测 发 现 5 种 kdr 等 位 基 因 类 型, 包 括 TTA (75.71%)、TTT (10.00%)、CTA (5.71%)、TCA (4.29%)、TTC (4.29%), 同时发现 2 种核苷酸非同义突变, 即亮氨酸 (L1014) 突变为苯丙氨酸 (L1014F)、丝氨酸 (L1014S)。罗村镇、太河 镇两地淡色库蚊 kdr 基因突变频率分别为 10.53%、40.63%, 差异具有统计学意义 ( χ ² = 8.559, P = 0.003)。 结论 淡色库 蚊为山东省淄博市淄川区优势蚊种。本研究首次在淡色库蚊中检测发现 CTA、TTC 两种 kdr 等位基因突变, kdr 基因型呈 多态性。