Insect Pest and Insect Vector Management/Ecotoxicology, Unité de Recherche en Ecotoxicologie (URET), Laboratoire d'Entomologie Appliquée (LEA), Faculté des Sciences, Université de Lomé, Lomé, Togo.
Noguchi Memorial Institute for Medical Research (NMIMR), University of Ghana, Legon, Accra, Ghana.
PLoS One. 2018 Jul 11;13(7):e0192492. doi: 10.1371/journal.pone.0192492. eCollection 2018.
LLINs containing an insecticide plus the synergist, piperonyl butoxide (PBO) have been designed for increased efficacy against pyrethroid-resistant malaria vectors. In this study, two LLINs with PBO, PermaNet® 3.0 and Olyset® Plus, and a pyrethroid-only LLIN, Yorkool®, were evaluated in experimental huts against a free-flying, wild population of Anopheles gambiae s.l. in Kolokopé, a cotton cultivated area of Togo. WHO susceptibility tube tests and subsequent molecular assays determine the An. gambiae s.l. populations to be resistant to pyrethroids and DDT with both target site kdr and metabolic resistance mechanisms involved in the resistance observed. Anopheles gambiae s.s. and An. coluzzi were present in sympatry though the kdr (L1014F) mutation was observed at a higher frequency in An. gambiae s.s. The experimental hut results showed that both PermaNet® 3.0 and Olyset® Plus nets induced similar levels of deterrence, exophily, and reduced blood feeding rate against wild An. gambiae s.l. in contrast to the pyrethroid only LLIN, Yorkool®. The proportion of wild An. gambiae s.l. killed by unwashed PermaNet® 3.0 was significantly higher than unwashed Olyset® Plus (corrected mortality 80.5% compared to 66.6%). Similar blood feeding inhibition rates were observed for unwashed PermaNet® 3.0 and Olyset® Plus; however, PermaNet® 3.0 washed 20 times demonstrated significantly higher blood feeding inhibition rate than Olyset® Plus washed 20 times (91.1% compared with 85.6% respectively). Yorkool® performed the worst for all the parameters evaluated. In an area of pyrethroid resistance of An. gambiae s.l involving kdr target site and metabolic resistance mechanisms, LLINs with PBO can provide additional protection in terms of reduction in blood feeding and increase in mosquito mortality compared to a pyrethroid-only net, and should be considered in malaria vector control strategies.
含增效剂增效醚（PBO）的长效驱虫蚊帐（LLINs）旨在提高对耐拟除虫菊酯疟疾媒介的效果。在这项研究中，在多哥棉花种植区科洛科普的野外，对两种含 PBO 的长效驱虫蚊帐（PermaNet® 3.0 和 Olyset® Plus）和一种仅含拟除虫菊酯的长效驱虫蚊帐（Yorkool®）进行了野外模拟帐野外试验，以评估其对自由飞行的野生冈比亚按蚊种群的效果。世界卫生组织敏感性管试验和随后的分子检测结果表明，冈比亚按蚊种群对拟除虫菊酯和滴滴涕均具有抗药性，涉及到观察到的抗药性的靶标位点 kdr 和代谢抗性机制均有参与。安蚊和安蚊科蚊同时存在，但 kdr（L1014F）突变在安蚊中的频率更高。野外模拟帐试验结果表明，PermaNet® 3.0 和 Olyset® Plus 网对野生冈比亚按蚊的驱避、嗜外性和减少吸血率的作用相似，而与仅含拟除虫菊酯的 Yorkool® LLIN 不同。未清洗的 PermaNet® 3.0 杀死的野生冈比亚按蚊比例明显高于未清洗的 Olyset® Plus（校正死亡率 80.5%，而 66.6%）。未清洗的 PermaNet® 3.0 和 Olyset® Plus 的吸血抑制率相似；然而，经 20 次洗涤的 PermaNet® 3.0 的吸血抑制率明显高于经 20 次洗涤的 Olyset® Plus（分别为 91.1%和 85.6%）。在评估的所有参数中，Yorkool® 的表现最差。在冈比亚按蚊涉及 kdr 靶标和代谢抗性机制的耐拟除虫菊酯地区，与仅含拟除虫菊酯的蚊帐相比，含增效剂的 LLINs 可在减少吸血和增加蚊虫死亡率方面提供额外的保护，应考虑将其纳入疟疾媒介控制策略。
