Background Long Lasting Insecticidal Nets (LLINs) and indoor residual spraying (IRS) represent powerful tools for controlling malaria vectors in sub-Saharan Africa. The success of these interventions relies on their capability to inhibit indoor feeding and resting of malaria mosquitoes. This study sought to understand the interaction of insecticide resistance with indoor and outdoor resting behavioral responses of malaria vectors from Western Kenya. Methods The status of insecticide resistance among indoor and outdoor resting anopheline mosquitoes was compared in Anopheles mosquitoes collected from Kisumu and Bungoma counties in Western Kenya. The level and intensity of resistance were measured using WHO-tube and CDC-bottle bioassays, respectively. The synergist piperonyl butoxide (PBO) was used to determine if metabolic activity (monooxygenase enzymes) explained the resistance observed. The mutations at the voltage-gated sodium channel ( Vgsc ) gene and Ace 1 gene were characterized using PCR methods. Microplate assays were used to measure levels of detoxification enzymes if present. Results A total of 1094 samples were discriminated within Anopheles gambiae s.l. and 289 within An. funestus s.l . In Kisian (Kisumu county), the dominant species was Anopheles arabiensis 75.2% (391/520) while in Kimaeti (Bungoma county) collections the dominant sibling species was Anopheles gambiae s.s 96.5% (554/574). The An. funestus s.l samples analysed were all An. funestus s.s from both sites. Pyrethroid resistance of An.gambiae s.l F1 progeny was observed in all sites. Lower mortality was observed against deltamethrin for the progeny of indoor resting mosquitoes compared to outdoor resting mosquitoes (Mortality rate: 37% vs 51%, P=0.044). The intensity assays showed moderate-intensity resistance to deltamethrin in the progeny of mosquitoes collected from indoors and outdoors in both study sites. In Kisian, the frequency of vgsc-L1014S and vgsc-L1014F mutation was 0.14 and 0.19 respectively in indoor resting malaria mosquitoes while those of the outdoor resting mosquitoes were 0.12 and 0.12 respectively. The ace 1 mutation was present in higher frequency in the F1 of mosquitoes resting indoors (0.23) compared to those of mosquitoes resting outdoors (0.12). In Kimaeti, the frequencies of vgsc-L1014S and vgsc-L1014F were 0.75 and 0.05 respectively for the F1 of mosquitoes collected indoors whereas those of outdoor resting ones were 0.67 and 0.03 respectively. The ace 1 G119S mutation was present in progeny of mosquitoes from Kimaeti resting indoors (0.05) whereas it was absent in those resting outdoors. Monooxygenase activity was elevated by 1.83 folds in Kisian and by 1.33 folds in Kimaeti for mosquitoes resting indoors than those resting outdoors respectively. Conclusion The study recorded high phenotypic, metabolic and genotypic insecticide resistance in indoor resting populations of malaria vectors compared to their outdoor resting counterparts. The indication of moderate resistance intensity for the indoor resting mosquitoes is alarming as it could have an operational impact on the efficacy of the existing pyrethroid based vector control tools. The use of synergist (PBO) in LLINs may be a better alternative for widespread use in these regions recording high insecticide resistance.

中文翻译：

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肯尼亚西部高地和低地遗址室内和室外静息疟疾媒介的杀虫剂抗药性状况

背景技术持久的杀虫网（LLIN）和室内残留喷雾（IRS）是控制撒哈拉以南非洲疟疾媒介的有力工具。这些干预措施的成功依赖于它们抑制疟疾蚊子在室内觅食和休息的能力。这项研究试图了解抗药性与肯尼亚西部疟疾媒介在室内和室外静息行为反应之间的相互作用。方法比较肯尼亚西部基苏木县和邦戈马县的室内和室外静息按蚊的抗药性状况。耐药水平和强度分别使用WHO管和CDC瓶生物测定法进行测量。增效剂胡椒基丁醚（PBO）用于确定代谢活性（单加氧酶）是否可以解释观察到的耐药性。利用PCR方法对电压门控钠通道（Vgsc）基因和Ace 1基因的突变进行了表征。如果有的话，用微孔板测定法测量解毒酶的水平。结果在冈比亚按蚊sl内共鉴定了1094个样品，而在按蚊中则鉴定了289个样品。funestus sl。在Kisian（Kisumu县），优势种为阿拉伯按蚊75.2％（391/520），而在Kimaeti（Bungoma县）集合中，优势兄弟种为冈比亚按蚊96.5％（554/574）。安。分析的funestus sl样品均为An。来自两个站点的funestus ss。在所有位点均观察到了冈比亚按蚊sl F1子代的拟除虫菊酯抗性。与室外休息的蚊子相比，室内休息的蚊子的后代中溴氰菊酯的死亡率较低（死亡率：37％vs 51％，P = 0.044）。强度测定表明，在两个研究地点从室内和室外采集的蚊子的后代中，对溴氰菊酯的中等强度抗性。在Kisian中，室内静息疟蚊的vgsc-L1014S和vgsc-L1014F突变频率分别为0.14和0.19，而室外静息蚊的频率分别为0.12和0.12。ace 1突变在室内蚊子（0.23）的F1中比在室外蚊子（0.12）的频率更高。在Kimaeti中，vgsc-L1014S和vgsc-L1014F的频率分别为0.75和0。在室内收集的蚊子的F1分别为05，而在室外休息的蚊子的F1分别为0.67和0.03。ace 1 G119S突变存在于室内休息的基迈蒂蚊子的后代中（0.05），而在室外休息的蚊子中则不存在。室内蚊子的单加氧酶活性在基西安人中增加了1.83倍，在基迈蒂提高了1.33倍。结论该研究表明，与室外休息的疟疾传播媒介相比，室内静止的疟疾媒介人群具有较高的表型，代谢和基因型杀虫剂抗药性。室内静息蚊的抵抗强度中等的指示令人震惊，因为这可能会对现有基于拟除虫菊酯的矢量控制工具的功效产生操作影响。