The selection and the spread of insecticide resistance in malaria vectors to the main classes of insecticides used in vector control tools are a major and ongoing challenge to malaria vector control programmes. This study aimed to determine the intensity of vector resistance to insecticides in three regions of Benin with different agro-ecological characteristics. Larvae of Anopheles gambiae sensu lato (s.l.) were collected from September to November 2017 in different larval sites in three northern Benin communes: Parakou, Kandi and Malanville. Two to five-day-old, non-blood-fed, female mosquitoes were exposed to papers impregnated with deltamethrin, permethrin and bendiocarb at dosages of 1 × the diagnostic dose, 5 × and 10 × to determine the intensity of resistance in these vectors. Molecular frequencies of the kdr L1014F and ace-1R G119S insecticide resistance mutations and levels of detoxification enzymes were determined for mosquitoes sampled at each study site. Resistance to pyrethroids (permethrin and deltamethrin) was recorded in all three communes with mortality rates below 60% using the diagnostic dose (1x). The results obtained after exposure of An. gambiae to permethrin 10 × were 99% in Kandi, 98% in Malanville and 99% in Parakou. With deltamethrin 10x, mortality rates were 100% in Kandi, 96% in Malanville and 73% in Parakou. For the diagnostic dose of bendiocarb, suspected resistance was recorded in the communes of Malanville (97%) and Kandi (94%) while sensitivity was observed in Parakou (98%).Using the 10 × dose, mortality was 98% in Kandi, 100% in Malanville and 99% in Parakou. The frequencies of the kdr L1014F allele varied between 59 and 83% depending on the sites and species of the An. gambiae complex, while the frequency of the ace-1R G119S gene varied between 0 and 5%. Biochemical tests showed high levels of oxidase and esterase activity compared to the susceptible colony strain of An. gambiae sensu stricto (Kisumu strain). Anopheles gambiae showed a generalized loss of susceptibility to permethrin and deltamethrin but also showed moderate to high intensity of resistance in different regions of Benin. This high intensity of resistance is a potential threat to the effectiveness of vector control.

中文翻译：

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西非贝宁北部三个社区冈比亚按蚊抗性特征（强度和机制）的表征

疟疾病媒对杀虫剂抗药性的选择和传播到病媒控制工具中使用的主要杀虫剂类别是对疟疾病媒控制计划的主要和持续挑战。本研究旨在确定贝宁三个具有不同农业生态特征的地区的病媒对杀虫剂的抗药性强度。2017 年 9 月至 11 月，在贝宁北部三个公社的不同幼虫地点收集了冈比亚按蚊 (sl) 幼虫：Parakou、Kandi 和 Malanville。将 2 至 5 天大、不喂血的雌性蚊子暴露于含有 1 倍诊断剂量、5 倍和 10 倍剂量的溴氰菊酯、氯菊酯和苯菌威的纸上，以确定这些载体的抵抗强度. 确定了在每个研究地点采样的蚊子的 kdr L1014F 和 ace-1R G119S 杀虫剂抗性突变的分子频率和解毒酶的水平。在使用诊断剂量 (1x) 的死亡率低于 60% 的所有三个社区中，都记录了对拟除虫菊酯（氯菊酯和溴氰菊酯）的耐药性。An 曝光后获得的结果。冈比亚对氯菊酯 10 × 的影响在 Kandi 为 99%，在 Malanville 为 98%，在 Parakou 为 99%。使用溴氰菊酯 10x，Kandi 的死亡率为 100%，Malanville 为 96%，Parakou 为 73%。对于苯菌威的诊断剂量，在 Malanville (97%) 和 Kandi (94%) 的公社记录到疑似耐药性，而在 Parakou (98%) 观察到敏感性。使用 10 倍剂量，Kandi 的死亡率为 98%，马兰维尔 100% 和帕拉库 99%。kdr L1014F 等位基因的频率在 59% 到 83% 之间变化，这取决于 An 的位点和物种。冈比亚复合体，而 ace-1R G119S 基因的频率在 0 到 5% 之间变化。生化测试表明，与敏感的 An 菌落菌株相比，氧化酶和酯酶活性水平较高。gambiae sensu stricto（基苏木株）。冈比亚按蚊对氯菊酯和溴氰菊酯的敏感性普遍丧失，但在贝宁不同地区也表现出中等至高强度的耐药性。这种高强度的抗性是对病媒控制有效性的潜在威胁。生化测试表明，与 An 的易感菌落菌株相比，氧化酶和酯酶活性水平较高。gambiae sensu stricto（基苏木株）。冈比亚按蚊对氯菊酯和溴氰菊酯的敏感性普遍丧失，但在贝宁不同地区也表现出中等至高强度的耐药性。这种高强度的抗性是对病媒控制有效性的潜在威胁。生化测试表明，与敏感的 An 菌落菌株相比，氧化酶和酯酶活性水平较高。gambiae sensu stricto（基苏木株）。冈比亚按蚊对氯菊酯和溴氰菊酯的敏感性普遍丧失，但在贝宁不同地区也表现出中等至高强度的耐药性。这种高强度的抗性是对病媒控制有效性的潜在威胁。