电压门控钠离子通道基因I1532T突变与白纹伊蚊对菊酯类杀虫剂敏感性的相关性

目的 探讨I1532T突变与白纹伊蚊对氯菊酯和溴氰菊酯杀虫剂抗药性的相关性。方法 利用实验室饲养的白纹伊蚊长宁株作为试虫,分别对幼虫和成虫阶段,以幼虫浸渍法和成虫接触筒法对溴氰菊酯和氯菊酯的敏感性进行生物测定。收集生物测定死亡和存活的个体单只抽提基因组DNA,PCR扩增电压门控钠离子通道（voltage-gated sodium channel, VGSC）基因部分片段,测序并检测击倒抗性（knockdown resistance, kdr）突变情况,χ²检验I1532T与2种菊酯类杀虫剂抗药性的相关性。结果 幼虫浸渍法的结果显示,白纹伊蚊长宁株对氯菊酯和溴氰菊酯的LC₅₀分别是敏感品系的2.23倍和3.31倍,提示对2种杀虫剂均为敏感。成蚊接触筒测定的结果显示,接触氯菊酯和溴氰菊酯后成蚊的死亡率分别为74.69%和78.79%,提示白纹伊蚊长宁株对氯菊酯和溴氰菊酯均已产生抗性。本研究共测定了401只白纹伊蚊长宁株的VGSC基因部分片段,1532位点为突变基因型（突变纯合子ACC/ACC和野生突变杂合子ATC/ACC）的占59.10%,其余为野生型ATC/ATC,占40.90%;1534位点为突变基因型（突变纯合子TCC/TCC和野生突变杂合子TTC/TCC）的占4.49%,其余为野生型TTC/TTC,占95.51%。结果显示,白纹伊蚊幼虫氯菊酯或溴氰菊酯抗药性表型与敏感表型之间的I1532T突变频率差异均无统计学意义（P>0.05）;成虫的氯菊酯抗药性表型与敏感表型之间的I1532T等位基因型频率差异（P=0.019）和基因型频率差异（P=0.044）有统计学意义,而溴氰菊酯抗药性表型与敏感表型的I1532T等位基因型和基因型频率差异无统计学意义（P>0.05）。结论 VGSC基因I1532T突变使白纹伊蚊成虫对氯菊酯敏感性下降,但与溴氰菊酯敏感性无相关性。

Correlation between the mutation of allele I1532T in voltage-gated sodium channel (VGSC) gene and susceptibility of Aedes albopictus to pyrethroid insecticides

Objective This study explored the correlation between the I1532T mutation and Ae. albopictus insecticide resistance. Methods Larvae and adults' bioassays of insecticide resistance were performed using Ae. albopictus Changning strain, which has been bred in the laboratory. The susceptibility of larvae to deltamethrin and permethrin was tested by the larvae immersion method and the method to test the adults is the standard WHO tube bioassay. The genome DNA was extracted from single mosquito, and partial fragment of VGSC gene was amplified using PCR to detect kdr mutations. The correlation between I1532T and pyrethroid insecticide resistance were explored by Chi-squared Test. Results The LC₅₀ of Changning strain to permethrin and deltamethrin was 2.23 times and 3.31 times higher than that of susceptible strain. The mortality rate of adult mosquitoes exposed to permethrin and deltamethrin was respectively 74.69% and 78.79%. The results showed that larvae of Ae. albopictus Changning strain had no resistance to permethrin or deltamethrin, while adults showed resistance to both. The VGSC gene sequences of 401 Ae. albopictus Changning strains were detected. The mutant genotype (mutant homozygous ACC/ACC and wild mutant heterozygous ATC/ACC) at site 1532 accounted for 59.10%, and the rest was wild type ATC/ATC, accounting for 40.90%. The mutant genotype (mutant homozygous TCC/TCC and wild mutant heterozygous TTC/TCC) at site 1534 accounted for 4.49%, and the rest were wild type TTC/TTC, accounting for 95.51%. In larvae, the difference of the I1532T mutation frequency between the resistance and susceptibility phenotype to permethrin or deltamethrin had no statistical significance. (P>0.05) In adult, the difference of the allele I1532T frequency between permethrin resistance and susceptibility phenotype have statistical significance (P=0.019), and the same to the I1532T genotype frequency (P=0.044). But the difference of the I1532T mutation frequency between the deltamethrin resistance and susceptibility phenotype had no statistical significance (P>0.05). Conclusion The I1532T mutation of the VGSC gene is related to the permethrin resistance of the adult Ae. albopictus, which reduces the sensitivity, but has no correlation with the deltamethrin resistance.