Department of Animal and Environmental Biology, Faculty of Science, Delta State University, Abraka, Nigeria.
PLoS One. 2024 Aug 29;19(8):e0309199. doi: 10.1371/journal.pone.0309199. eCollection 2024.
The detection of insecticide resistance in male mosquitoes has been treated with less importance in monitoring insecticide resistance spread in mosquitoes. There are no studies on the susceptibility and synergistic activity of DDT and lambda-cyhalothrin on male Anopheles gambiae and Aedes aegypti in Delta State, Nigeria. Even though studies have extensively reported resistance in female mosquitoes, the susceptibility of male mosquitoes to insecticide classes should be ascertained. In this study, we tested the susceptibility status and synergistic activity of DDT and Lambda-cyhalothrin on An. gambiae and Ae. aegypti in Delta State, Nigeria, in order to ascertain the level of resistance and knockdown. In addition, we modelled the knockdown time using Probit analysis model. WHO bioassay method was used to expose two days old adult mosquitoes to 4% DDT and 0.05% lambda-cyhalothrin. The results showed that An. gambiae mosquitoes exposed to DDT and lambda-cyhalothrin were confirmed resistant (61% and 53% respectively). However, pre-exposing the resistant mosquito population to piperonyl butoxide (4%) showed an increase in mortality to 90% (possible resistance) in DDT and 98% (susceptible) in lambda-cyhalothrin. Ae. aegypti mosquitoes exposed to DDT were susceptible (98%) while those exposed to lambda-cyhalothrin were confirmed resistant (87%) and this increased to complete mortality (100%) in PBO+lambda-cyhalothrin population. Furthermore, the results showed that the knockdown time (KDT50 and KDT95) in An. gambiae exposed to DDT was 39.5-71.2 minutes and 124.5-146.4 minutes respectively, while that of lambda-cyhalothrin was 33.0-81.8 minutes and 64.0-124.4 minutes respectively. In Ae. aegypti, KDT50 and KDT95 was 23.9 and 61.7minutes for DDT exposure whereas it was 5.6-15.3 minutes and 36.1-72.3 minutes for lambda-cyhalothrin exposure. It can be concluded that male An. gambiae mosquitoes exposed to the insecticides were resistant and the causes may be linked to certain resistant genes in the mosquitoes. The chances of transferring resistance are possible in wild species and molecular-based studies on the resistant gene in male mosquitoes as well as the tendencies of transfer are required to establish this focus.
在监测杀虫剂抗性传播方面，雄性蚊子的杀虫剂抗性检测一直没有得到重视。在尼日利亚三角洲州，尚未有关于滴滴涕和氯氟氰菊酯对雄性冈比亚按蚊和埃及伊蚊敏感性和增效作用的研究。尽管有研究广泛报道了雌性蚊子的抗药性，但仍需确定雄性蚊子对杀虫剂类别的敏感性。在这项研究中，我们测试了滴滴涕和氯氟氰菊酯对尼日利亚三角洲州冈比亚按蚊和埃及伊蚊的敏感性和增效作用，以确定其抗药性和击倒水平。此外，我们使用概率分析模型来模拟击倒时间。采用世界卫生组织生物测定法，将两天大的成年蚊子暴露于 4%滴滴涕和 0.05%氯氟氰菊酯中。结果表明，接触滴滴涕和氯氟氰菊酯的冈比亚按蚊被证实具有抗药性（分别为 61%和 53%）。然而，预先将抗药性蚊种群暴露于增效醚（4%）中，滴滴涕的死亡率增加到 90%（可能具有抗药性），氯氟氰菊酯的死亡率增加到 98%（敏感）。接触滴滴涕的埃及伊蚊为敏感（98%），而接触氯氟氰菊酯的埃及伊蚊则被证实具有抗药性（87%），在增效醚+氯氟氰菊酯种群中，死亡率增加到 100%。此外，结果表明，接触滴滴涕的冈比亚按蚊的击倒时间（KDT50 和 KDT95）分别为 39.5-71.2 分钟和 124.5-146.4 分钟，而接触氯氟氰菊酯的 KDT50 和 KDT95 分别为 33.0-81.8 分钟和 64.0-124.4 分钟。在埃及伊蚊中，接触滴滴涕的 KDT50 和 KDT95 分别为 23.9 和 61.7 分钟，而接触氯氟氰菊酯的 KDT50 和 KDT95 分别为 5.6-15.3 分钟和 36.1-72.3 分钟。可以得出结论，接触杀虫剂的雄性冈比亚按蚊具有抗药性，其原因可能与蚊子体内的某些抗性基因有关。在野生种群中，抗药性可能会转移，需要进行基于分子的雄性蚊子抗性基因研究以及转移趋势研究，以确定这一重点。
