Institut Pierre Richet (IPR), BP 47 Abidjan, Côte d'Ivoire.
Parasit Vectors. 2012 Apr 2;5:68. doi: 10.1186/1756-3305-5-68.
At Yaokoffikro field site near Bouaké, in central Côte d'Ivoire, a group of experimental huts built in 1996 served over many years for the evaluation of insecticides against highly resistant mosquitoes. Breeding sites of mosquitoes and selection pressure in the area were maintained by local farming practices until a war broke out in September 2002. Six years after the crisis, we conducted bioassays and biochemical analysis to update the resistance status of Anopheles gambiae s.s. populations and detect other potential mechanisms of resistance that might have evolved.
An. gambiae s.s. larvae from Yaokoffikro were collected in breeding sites and reared to adults. Resistance status of this population to insecticides was assessed using WHO bioassay test kits for adult mosquitoes with seven insecticides: two pyrethroids, a pseudo-pyrethroid, an organochloride, two carbamates and an organophosphate.Molecular and biochemical assays were carried out to identify the L1014F kdr and ace-1R alleles in individual mosquitoes and to detect potential increase in mixed function oxidases (MFO), non-specific esterases (NSE) and glutathione S-transferases (GST) activity.
High pyrethroids, DDT and carbamate resistance was confirmed in An. gambiae s.s. populations from Yaokoffikro. Mortality rates were less than 70% with pyrethroids and etofenprox, 12% with DDT, and less than 22% with the carbamates. Tolerance to fenitrothion was observed, with 95% mortality after 24 h.PCR analysis of samples from the site showed high allelic frequency of the L1014F kdr (0.94) and the ace-1R (0.50) as before the crisis. In addition, increased activity of NSE, GST and to a lesser extent MFO was found relative to the reference strain Kisumu. This was the first report detecting enhanced activity of these enzymes in An. gambiae s.s from Yaokoffikro, which could have serious implications in detoxification of insecticides. Their specific roles in resistance should be investigated using additional tools.
The insecticide resistance profile at Yaokoffikro appears multifactorial. The site presents a unique opportunity to evaluate its impact on the protective efficacy of insecticidal products as well as new tools to manage these complex mechanisms. It calls for innovative research on the behaviour of the local vector, its biology and genetics that drive resistance.
在科特迪瓦中部布瓦凯附近的 Yaokoffikro 野外试验场，1996 年建造的一组实验棚多年来一直用于评估杀虫剂对高度耐药蚊子的效果。在 2002 年 9 月爆发战争之前，该地区的蚊子繁殖地和选择压力一直由当地农业实践维持。危机发生六年后，我们进行了生物测定和生化分析，以更新抗药性疟蚊种群的抗药性状况，并发现可能已经进化出的其他潜在抗药性机制。
从 Yaokoffikro 的蚊子滋生地收集 Yaokoffikro 的 An. gambiae s.s. 幼虫并饲养成成虫。使用世界卫生组织（WHO）针对成蚊的生物测定试剂盒，评估该人群对七种杀虫剂的抗药性：两种拟除虫菊酯、一种拟除虫菊酯、一种有机氯、两种氨基甲酸酯和一种有机磷。对个体蚊子进行 L1014F kdr 和 ace-1R 等位基因的分子和生化检测，并检测混合功能氧化酶（MFO）、非特异性酯酶（NSE）和谷胱甘肽 S-转移酶（GST）活性是否增加。
在 Yaokoffikro 的 An. gambiae s.s. 种群中证实了对拟除虫菊酯、DDT 和氨基甲酸酯的高抗药性。用拟除虫菊酯和乙氰菊酯处理的死亡率低于 70%，用滴滴涕处理的死亡率为 12%，用氨基甲酸酯处理的死亡率低于 22%。用 fenitrothion 处理时观察到耐受性，24 小时后死亡率为 95%。该地点的 PCR 分析显示，L1014F kdr（0.94）和 ace-1R（0.50）的等位基因频率很高，与危机前一样。此外，与参考菌株 Kisumu 相比，发现 NSE、GST 和 MFO 的活性增加，而 MFO 的活性增加程度较低。这是首次报道在 Yaokoffikro 的 An. gambiae s.s. 中检测到这些酶的活性增强，这可能对杀虫剂解毒有严重影响。应该使用其他工具来研究它们在抗药性中的特定作用。
Yaokoffikro 的杀虫剂抗药性谱似乎是多因素的。该地点为评估其对杀虫产品保护效果的影响以及管理这些复杂机制的新工具提供了独特的机会。这需要对当地蚊子的行为、生物学和遗传学进行创新性研究，这些因素推动了抗药性的产生。
