BACKGROUND In 2011, Benin's National Malaria Control Programme (NMCP) organized a nationwide mass distribution campaign of LLINs throughout the country. Following this intervention, it was important to assess whether the level of susceptibility of malaria vectors to insecticides had remained the same as compared to the pre-intervention period. The current study investigated this. METHODS Larval collections were conducted in Ifangni, Sakété, Pobè and Kétou districts located in Plateau department, Southeastern Benin before (2009) and after (2012-2013) LLIN distribution. Anopheles gambiae sensu lato (s.l.) larvae from the 4 study districts were reared to adulthood and WHO susceptibility tests were conducted. The insecticides tested were deltamethrin (0.05%), permethrin (0.75%), bendiocarb (0.1%) and DDT (4%). Molecular species identification as well as, the characterization of the kdr L1014F mutation were also performed in the An. gambiae s.l. complex using PCR method. RESULTS Overall, a significant decrease in mortality rates of An. gambiae s.l. to deltamethrin (0.05%), permethrin (0.75%) and DDT (4%) was observed post-LLIN distribution, respectively: (100% vs 80.9%, p < 0.0001), (77.5% vs 70%, p = 0.01) and, (47.8% vs 4.4%, p < 0.0001). By contrast, susceptibility of vectors to bendiocarb (0.1%) remained the same (100% mortality in the WHO susceptibility tube tests) pre- and post-intervention. An increase in the kdr L1014F frequency was observed post-LLIN distribution [F(kdr) = 0.91)] compared to the pre-intervention period [F(kdr) = 0.56], p < 0.0001. Anopheles coluzzii and An. gambiae were the two molecular species identified in the study area. CONCLUSION The decrease susceptibility to pyrethroids and DDT as well as, the increase in the frequency of the kdr L1014F mutation after the intervention stressed at the time, the need for the development and implementation of effective insecticide resistance management strategies. At present, an update of the vectors resistance status in the area is also necessary for decision-making.

中文翻译：

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在2011年贝宁东南部高原部的长效杀虫网（LLIN）大规模分发活动之后，冈比亚按蚊sl对杀虫剂的抗药性。

背景技术2011年，贝宁的国家疟疾控制计划（NMCP）在全国范围内组织了LLIN的全国性大规模分发活动。经过这一干预，重要的是评估与干预前相比，疟疾媒介对杀虫剂的敏感性水平是否保持不变。当前的研究对此进行了调查。方法在LLIN分布之前（2009年）和之后（2012-2013年），在贝宁东南部高原部的Ifangni，Sakété，Pobè和Kétou地区进行幼虫收集。将来自四个研究区的冈比亚按蚊的幼虫饲养到成年，并进行了WHO药敏试验。测试的杀虫剂为溴氰菊酯（0.05％），苄氯菊酯（0.75％），苯达威（0.1％）和滴滴涕（4％）。分子种类鉴定以及kdr L1014F突变的表征也在An中进行。冈比亚sl复杂使用PCR方法。结果总的来说，An的死亡率显着降低。LLIN分布后观察到冈比亚sl到溴氰菊酯（0.05％），苄氯菊酯（0.75％）和DDT（4％）：（100％vs 80.9％，p <0.0001），（77.5％vs 70％，p = 0.01）和（47.8％vs 4.4％，p <0.0001）。相比之下，在干预前后，载体对苯达威的敏感性（0.1％）保持不变（在WHO敏感性管试验中，死亡率为100％）。与干预前期[F（kdr）= 0.56]相比，LLIN分布后的kdr L1014F频率增加[F（kdr）= 0.91）]，p <0.0001。按蚊和An。冈比亚是研究区域确定的两个分子物种。结论当时强调的是干预后对拟除虫菊酯和DDT的敏感性降低以及kdr L1014F突变的频率增加，因此需要制定和实施有效的杀虫剂抗性管理策略。目前，还需要对该区域中的矢量抗性状态进行更新以进行决策。