Knockdown resistance gene mutations of Aedes albopictus from Fuzhou and Putian, Fujian, 2020

Abstract

Objective To understand the mutations of knockdown resistance ( kdr) gene of Aedes albopictus in dengue fever surveillance sites in Fuzhou and Putian. Methods From May to June in 2020, Aedes albopictus larvae were collected from Fuzhou (Jin’an District, Yongtai County) and Putian (Hanjiang District and Xianyou County), and then reared and reproduced in lab. DNA was extracted from each single female mosquito of F 1 generation after the exposure tubes method on adults. Using PCR to amplify partial fragments of the voltage-gated sodium channel (VGSC) gene on the nerve cell membrane. The mutations in the kdr gene were analyzed by sequencing. Results A total of 491 Aedes albopictus were detected in Fuzhou and Putian, in which no mutation was found in domain II or at I1532 locus in domain III, but there were mutations at F1534 locus in domain III of the VGSC gene. There were four alleles at the F1534 locus, namely wild-type TTC/F (252, 25.66%), mutant TCC/S (722, 73.52%), mutant TGC/C (3, 0.31%), and mutant CTC/L (5, 0.51%); seven genotypes, i.e., the wild-type homozygote F/F (39, 7.94%), wild/mutant heterozygote F/C (1, 0.20%), F/S (172, 35.03%) and F/L (1, 0.20%), mutant heterozygote S/C (2, 0.41%) and S/L (4, 0.81%), and mutant homozygote S/S (272, 55.40%). Mutant allele TCC/S at F1534 locus was found in all four populations and the frequencies in Hanjiang and Xianyou were higher than those in Jin’an and Yongtai. There were five genotypes at F1534 locus in Jin’an and Yongtai, but only three genotypes in Hanjiang and Xianyou. Wild/mutant heterozygote F/S and mutant homozygote S/S were found in all four populations, but wild-type homozygote F/F was not found in Hanjiang. The main genotype in Jin’an and Yongtai was F/S, while that in Hanjiang and Xianyou was S/S. Conclusion The kdr gene mutation rate is high in Fuzhou and Putian and F1534S is the main mutation type. This suggests that we should pay close attention to the resistance level of local mosquitos, reduce the use of pyrethroid insecticides, and use insecticides scientifically and rationally. 摘要： 目的 了解福州市和莆田市登革热伊蚊监测点白纹伊蚊击倒抗性基因的突变情况。 方法 2020 年 5—6 月在福州市(晋安区、永泰县)和莆田市 (涵江区、仙游县) 采集白纹伊蚊幼虫, 饲养繁殖, 使用成蚊接触筒法实验结束 的F 1代单只雌蚊样本, 提取 DNA, PCR 扩增电压门控钠离子通道 (VGSC) 基因部分片段, 测序分析击倒抗性 (knockdown resistance, kdr) 基因突变情况。 结果 福州市和莆田市共检测 491 只白纹伊蚊, 其中 VGSC 基因第 II 结构域及第 III 结构域的 I1532 位点未发现突变位点, 第 III 结构域的 F1534 位点存在突变。F1534 位点有 4 种等位基因, 即野生型 TTC/F(252,25.66%)、突变型 TCC/S(722, 73.52%)、TGC/C(3, 0.31%) 和 CTC/L(5, 0.51%); 7 种基因型, 分别为野生型 纯合子 F/F (39,7.94%), 野生/突变型杂合子 F/C (1,0.20%)、F/S (172,35.03%) 和 F/L (1, 0.20%), 突变型杂合子 S/C (2,0.41%) 和 S/L (4,0.81%), 突变型纯合子 S/S (272,55.40%)。F1534 位点突变等位基因 TCC/S 在 4 个种群中均有发现, 且莆田市涵江区和仙游县的频率髙于福州市晋安区和永泰县的频率。晋安区和永泰县 F1534 位点存在 5 种基因型, 涵江区和仙游县则只有 3 种。野生/突变型杂合子 F/S 和突变型纯合子 S/S 在 4 个种群中均存在, 野生型纯合子 F/F 只 在涵江区中没有发现。晋安区和永泰县基因型以 F/S 为主, 涵江区和仙游县以 S/S 为主。 结论 福州市和莆田市 kdr 基因突变频率髙, 以 F1534S 突变类型为主。提示应密切关注当地蚊虫抗性水平, 减少拟除虫菊酯类杀虫剂的使用, 科学合理地使用杀虫剂。