Spitzen Jeroen, Koelewijn Teun, Mukabana W Richard, Takken Willem
Laboratory of Entomology, Wageningen University, PO Box 16, 6700 AA Wageningen, The Netherlands.
International Centre of Insect Physiology and Ecology (icipe), P.O. Box 30772-00100, Nairobi, Kenya; Science for Health, P.O. Box 44970-00100, Nairobi, Kenya.
Acta Trop. 2017 Aug;172:180-185. doi: 10.1016/j.actatropica.2017.05.008. Epub 2017 May 8.
Insecticide-treated nets are currently a major tool to reduce malaria transmission. Their level of repellency affects contact of the mosquito with the net, but may also influence the mosquito's entry into the house. The response of host-seeking malaria mosquitoes approaching the eave of an experimental house was recorded within a large screen house. We compared entry- and exit rates in relation to the presence in the house of different insecticide-treated bed nets (ITNs) with an untreated net. Mosquitoes were lured towards the house by dispensing a synthetic host-odour blend from within the net in the house. Complementary WHO bioassays revealed that the treated nets caused high knock-down- and mortality responses to the Anopheles gambiae sensu stricto strain tested. The proportion of mosquitoes that came into view of the cameras and subsequently entered the house did not differ between treated nets and the untreated net. Treated nets did not affect proportions of mosquitoes that exited the house and departed from view around the eave. However, the percentage of house-leaving and re-entering mosquitoes when an insecticide- treated net was present, was lower than in the presence of an untreated net. Our results indicated that there was no spatial repellent effect from pyrethroid-treated nets that influences house-entry at eave level. It is argued that the toxic effect of treated bed nets resulted in a reduced number of mosquitoes re-entering the house, which could thereby affect malaria transmission in neighbouring, unprotected houses.
经杀虫剂处理的蚊帐是目前减少疟疾传播的主要工具。其驱避程度会影响蚊子与蚊帐的接触，但也可能影响蚊子进入房屋的情况。在一个大型网室内记录了寻找宿主的疟疾蚊子接近实验房屋屋檐时的反应。我们比较了不同经杀虫剂处理的蚊帐（ITN）与未处理蚊帐在房屋内时蚊子的进入率和退出率。通过在房屋内的蚊帐中释放合成宿主气味混合物，将蚊子引诱到房屋。补充的世卫组织生物测定表明，经处理的蚊帐对所测试的冈比亚按蚊指名亚种菌株引起了高击倒率和死亡率反应。在经处理的蚊帐和未处理的蚊帐之间，进入摄像头视野并随后进入房屋的蚊子比例没有差异。经处理的蚊帐不影响蚊子离开房屋并在屋檐周围离开视野的比例。然而，当存在经杀虫剂处理的蚊帐时，离开房屋并重新进入的蚊子百分比低于存在未处理蚊帐时。我们的结果表明，拟除虫菊酯处理的蚊帐没有影响屋檐水平处房屋进入的空间驱避效果。有人认为，经处理的蚊帐的毒性作用导致重新进入房屋的蚊子数量减少，从而可能影响邻近未受保护房屋中的疟疾传播。
