Tambwe Mgeni Mohamed, Mbeyela Edgar Mtaki, Massinda Brian Migamyo, Moore Sarah Jane, Maia Marta Ferreira
Ifakara Health Institute, Intervention and Environmental Health and Ecological Sciences, P.O. Box 74, Bagamoyo, Tanzania.
Swiss Tropical & Public Health Institute, Soccinstraße 57, 4002, Basel, Switzerland.
Parasit Vectors. 2014 Dec 5;7:550. doi: 10.1186/s13071-014-0550-2.
Malaria vector control is in need of new tools to face its current challenges such as the spread of pyrethroid-resistance and the increase of outdoor feeding mosquitoes. New strategies such as spatial repellents need to be evaluated as supplemental tools to existing control measures such as insecticide treated bed nets and indoor residual spraying. Linalool is a naturally occurring terpene alcohol commonly found in flowers and spices with reportedly repellent properties.
Four experimental huts fitted with exit traps and enclosed inside a large screened semi-field system were used for the evaluation. The tested spatial repellent product consisted of an agar gel emanator containing 73% linalool. Two rounds of experiments using a Latin square design were conducted to evaluate the efficacy of the linalool emanators compared to no treatment (negative control) and a transfluthrin coil (positive) against lab-reared disease free Anopheles gambiae s.s.. The emanators were hung inside experimental huts where two volunteers were sleeping unprotected. The outcome measures were repellency, % feeding inhibition, %mortality and post 24 h % mortality.
Unlike the mosquito coil, the linalool emanators did not show any feeding inhibition, repellency or induced mortality compared to the negative control. On the other hand mosquitoes kept for 24 h post exposure were 3 times more likely to die after being exposed to two 73% linalool emanators than the negative control.
Our results indicate that linalool agar gel emanators are not adequate as a spatial repellent against Anopheles gambiae s.s.. However adding linalool to known repellent formulations could be advantageous, not only because of its pleasant scent but also because of the delayed mortality effect it has on mosquitoes.
疟疾媒介控制需要新工具来应对当前面临的挑战，如拟除虫菊酯抗性的传播和户外叮咬蚊子数量的增加。诸如空间驱避剂等新策略需要作为现有控制措施（如杀虫剂处理蚊帐和室内滞留喷洒）的补充工具进行评估。芳樟醇是一种天然存在的萜烯醇，常见于花卉和香料中，据报道具有驱避特性。
使用四个装有出口诱捕器并封闭在大型防虫半野外系统内的实验小屋进行评估。测试的空间驱避产品为含有73%芳樟醇的琼脂凝胶散发器。采用拉丁方设计进行两轮实验，以评估芳樟醇散发器与未处理组（阴性对照）和氟氯氰菊酯盘香（阳性对照）相比，对实验室饲养的无病冈比亚按蚊的效果。散发器悬挂在实验小屋内，两名志愿者在无保护状态下睡觉。观察指标为驱避性、摄食抑制率、死亡率以及24小时后的死亡率。
与阴性对照相比，与蚊香不同，芳樟醇散发器未表现出任何摄食抑制、驱避或诱导死亡的情况。另一方面，暴露后饲养24小时的蚊子，在接触两个73%芳樟醇散发器后死亡的可能性是阴性对照的3倍。
我们的结果表明，芳樟醇琼脂凝胶散发器作为冈比亚按蚊的空间驱避剂效果不佳。然而，将芳樟醇添加到已知的驱避剂配方中可能具有优势，这不仅是因为其宜人的气味，还因为它对蚊子具有延迟死亡效应。
