BACKGROUND In the Republic of Congo, with two massive outbreaks of chikungunya observed this decade, little is known about the insecticide resistance profile of the two major arbovirus vectors Aedes aegypti and Aedes albopictus. Here, we established the resistance profile of both species to insecticides and explored the resistance mechanisms to help Congo to better prepare for future outbreaks. METHODS Immature stages of Ae. aegypti and Ae. albopictus were sampled in May 2017 in eight cities of the Republic of the Congo and reared to adult stage. Larval and adult bioassays, and synergist (piperonyl butoxide [PBO]) assays were carried out according to WHO guidelines. F1534C mutation was genotyped in field collected adults in both species and the polymorphism of the sodium channel gene assessed in Ae. aegypti. RESULTS All tested populations were susceptible to temephos after larval bioassays. A high resistance level was observed to 4% DDT in both species countrywide (21.9-88.3% mortality). All but one population (Ae. aegypti from Ngo) exhibited resistance to type I pyrethroid, permethrin, but showed a full susceptibility to type II pyrethroid (deltamethrin) in almost all locations. Resistance was also reported to 1% propoxur in Ae. aegypti likewise in two Ae. albopictus populations (Owando and Ouesso), and the remaining were fully susceptible. All populations of both species were fully susceptible to 1% fenitrothion. A full recovery of susceptibility was observed in Ae. aegypti and Ae. albopictus when pre-exposed to PBO and then to propoxur and permethrin respectively. The F1534C kdr mutation was not detected in either species. The high genetic variability of the portion of sodium channel spanning the F1534C in Ae. aegypti further supported that knockdown resistance probably play no role in the permethrin resistance. CONCLUSIONS Our study showed that both Aedes species were susceptible to organophosphates (temephos and fenitrothion), while for other insecticide classes tested the profile of resistance vary according to the population origin. These findings could help to implement better and efficient strategies to control these species in the Congo in the advent of future arbovirus outbreaks.

中文翻译：

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中非刚果共和国两种主要虫媒病毒载体埃及伊蚊和白纹伊蚊对 I 型和 II 型拟除虫菊酯的耐药模式对比。


背景技术在刚果共和国，近十年来观察到两次大规模的基孔肯雅热疫情，人们对两种主要虫媒病毒载体埃及伊蚊和白纹伊蚊的杀虫剂抗药性知之甚少。在这里，我们建立了这两个物种对杀虫剂的抗性概况，并探讨了抗性机制，以帮助刚果更好地为未来的疫情爆发做好准备。方法 Ae 的未成熟阶段。埃及伊蚊和伊蚊。 2017 年 5 月在刚果共和国的八个城市对白纹伊蚊进行了采样并饲养至成虫阶段。幼虫和成虫生物测定以及增效剂（胡椒基丁醚[PBO]）测定是根据世界卫生组织指南进行的。在野外收集的两个物种的成虫中对 F1534C 突变进行基因分型，并评估了伊蚊中钠通道基因的多态性。埃及伊蚊。结果 幼虫生物测定后，所有测试群体均对替美磷敏感。在全国范围内，这两个物种均观察到对 4% DDT 的高耐药性（死亡率为 21.9-88.3%）。除一个种群（来自 Ngo 的埃及伊蚊）外，所有种群均表现出对 I 型拟除虫菊酯、氯菊酯的抗性，但在几乎所有地点都表现出对 II 型拟除虫菊酯（溴氰菊酯）的完全敏感性。据报道，白藜芦醇对 1% 残杀威也有耐药性。埃及伊蚊同样存在于两个伊蚊中。白纹伊蚊种群（Owando 和 Ouesso），其余种群完全易感。两个物种的所有种群均对 1% 杀螟硫磷完全敏感。在 Ae 中观察到敏感性完全恢复。埃及伊蚊和伊蚊。白纹伊蚊先暴露于 PBO，然后分别暴露于残杀威和氯菊酯。在这两个物种中均未检测到 F1534C kdr 突变。伊蚊中跨越 F1534C 的钠通道部分的高遗传变异性。 埃及伊蚊进一步支持击倒抗性可能在氯菊酯抗性中不起任何作用。结论 我们的研究表明，两种伊蚊都对有机磷酸酯（替灭磷和杀螟硫磷）敏感，而对于测试的其他杀虫剂类别，其抗药性随种群起源而变化。这些发现可能有助于在未来虫媒病毒爆发时实施更好、更有效的策略来控制刚果的这些物种。