UMRI 28, Sciences Agronomiques et Procédés de Transformation, Laboratoire de Zoologie Agricole et Entomologie, Institut National Polytechnique Félix Houphouët-Boigny (INP-HB), Yamoussoukro, République de Côte d'Ivoire.
Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, Abidjan, République de Côte d'Ivoire.
Malar J. 2024 May 22;23(1):160. doi: 10.1186/s12936-024-04917-y.
Anopheles mosquito resistance to insecticide remains a serious threat to malaria vector control affecting several sub-Sahara African countries, including Côte d'Ivoire, where high pyrethroid, carbamate and organophosphate resistance have been reported. Since 2017, new insecticides, namely neonicotinoids (e.g.; clothianidin) and pyrroles (e.g.; chlorfenapyr) have been pre-qualified by the World Health Organization (WHO) for use in public health to manage insecticide resistance for disease vector control.
Clothianidin and chlorfenapyr were tested against the field-collected Anopheles gambiae populations from Gagnoa, Daloa and Abengourou using the WHO standard insecticide susceptibility biossays. Anopheles gambiae larvae were collected from several larval habitats, pooled and reared to adulthood in each site in July 2020. Non-blood-fed adult female mosquitoes aged 2 to 5 days were exposed to diagnostic concentration deltamethrin, permethrin, alpha-cypermethrin, bendiocarb, and pirimiphos-methyl. Clothianidin 2% treated papers were locally made and tested using WHO tube bioassay while chlorfenapyr (100 µg/bottle) was evaluated using WHO bottle assays. Furthermore, subsamples of exposed mosquitoes were identified to species and genotyped for insecticide resistance markers including the knock-down resistance (kdr) west and east, and acetylcholinesterase (Ace-1) using molecular techniques.
High pyrethroid resistance was recorded with diagnostic dose in Abengourou (1.1 to 3.4% mortality), in Daloa (15.5 to 33.8%) and in Gagnoa (10.3 to 41.6%). With bendiocarb, mortality rates ranged from 49.5 to 62.3%. Complete mortality (100% mortality) was recorded with clothianidin in Gagnoa, 94.9% in Daloa and 96.6% in Abengourou, while susceptibility (mortality > 98%) to chlorfenapyr 100 µg/bottle was recorded at all sites and to pirimiphos-methyl in Gagnoa and Abengourou. Kdr-west mutation was present at high frequency (0.58 to 0.73) in the three sites and Kdr-east mutation frequency was recorded at a very low frequency of 0.02 in both Abengourou and Daloa samples and absent in Gagnoa. The Ace-1 mutation was present at frequencies between 0.19 and 0.29 in these areas. Anopheles coluzzii represented 100% of mosquitoes collected in Daloa and Gagnoa, and 72% in Abengourou.
This study showed that clothianidin and chlorfenapyr insecticides induce high mortality in the natural and pyrethroid-resistant An. gambiae populations in Côte d'Ivoire. These results could support a resistance management plan by proposing an insecticide rotation strategy for vector control interventions.
伊蚊对杀虫剂的抗药性仍然是对包括科特迪瓦在内的几个撒哈拉以南非洲国家疟疾媒介控制的严重威胁，科特迪瓦报告了高水平的拟除虫菊酯、氨基甲酸酯和有机磷抗性。自 2017 年以来，新的杀虫剂，即新烟碱类（如氯噻啉）和吡咯类（如氯氟氰菊酯）已被世界卫生组织（世卫组织）预先批准用于公共卫生，以管理疾病媒介控制中的杀虫剂抗性。
使用世界卫生组织标准杀虫剂敏感性生物测定法，对来自加尼奥阿、达洛亚和阿本古鲁的现场采集的冈比亚按蚊种群进行氯噻啉和氯氟氰菊酯测试。冈比亚按蚊幼虫从几个幼虫栖息地收集，在 2020 年 7 月在每个地点混合并饲养至成虫。未吸血的 2 至 5 天龄雌性成年蚊子暴露于诊断浓度的溴氰菊酯、氯菊酯、α-氯氰菊酯、涕灭威和吡虫啉。氯噻啉 2%处理纸是在当地制作的，并使用世界卫生组织管生物测定法进行测试，而氯氟氰菊酯（100µg/瓶）则使用世界卫生组织瓶测定法进行评估。此外，用分子技术对暴露的蚊子进行了亚抽样，以确定其物种，并对击倒抗性（kdr）西和东以及乙酰胆碱酯酶（Ace-1）的杀虫剂抗性标记进行基因分型。
在阿本古鲁（死亡率为 1.1%至 3.4%）、达洛亚（死亡率为 15.5%至 33.8%）和加尼奥阿（死亡率为 10.3%至 41.6%），记录了高水平的拟除虫菊酯抗性。用涕灭威，死亡率范围为 49.5%至 62.3%。在加尼奥阿，氯噻啉的死亡率为 100%，在达洛亚和阿本古鲁，死亡率为 94.9%和 96.6%，记录了完全死亡率（死亡率为 100%），而对 100µg/瓶的氯氟氰菊酯和加尼奥阿和阿本古鲁的吡虫啉的敏感性（死亡率>98%）。在三个地点均发现 kdr-west 突变的高频率（0.58 至 0.73），在阿本古鲁和达洛亚样本中 kdr-east 突变频率非常低，为 0.02，而在加尼奥阿样本中则不存在。这些地区的 Ace-1 突变频率在 0.19 至 0.29 之间。在达洛亚和加尼奥阿采集的蚊子中，冈比亚按蚊的比例为 100%，在阿本古鲁为 72%。
本研究表明，氯噻啉和氯氟氰菊酯杀虫剂在科特迪瓦的天然和拟除虫菊酯抗性冈比亚按蚊种群中诱导了高死亡率。这些结果可以支持抗药性管理计划，提出一种用于媒介控制干预的杀虫剂轮换策略。
