Kawada Hitoshi, Dida Gabriel O, Ohashi Kazunori, Kawashima Emiko, Sonye George, Njenga Sammy M, Mwandawiro Charles, Minakawa Noboru
Department of Vector Ecology and Environment, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan.
Department of Vector Ecology and Environment, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan; School of Public Health, Maseno University, Kisumu, Kenya.
PLoS One. 2014 Oct 21;9(10):e111195. doi: 10.1371/journal.pone.0111195. eCollection 2014.
Pyrethroid resistance is becoming a major problem for vector control programs, because at present, there are few suitable chemical substitutes for pyrethroids, as when used on bed nets the insecticide must have low mammalian toxicity as well as high activity to mosquitoes. Pyriproxyfen (PPF) is one of the most active chemicals among the juvenile hormone mimic (JHM) group. Sterilizing mosquitoes by using PPF could be a potential control measure for pyrethroid-resistant malaria vectors. We investigated the sterilizing effects of two types of PPF-impregnated bed nets - a 1% PPF-impregnated net and a 1% PPF +2% permethrin-impregnated net (Olyset Duo) - to pyrethroid-resistant wild population of Anopheles gambiae s.s. in western Kenya. High mortality of blood-fed mosquitos was observed 3 days post-collection, in the houses where PPF-impregnated nets were used, indicating the effect of PPF on the longevity of mosquitos that came in contact with the net. Reduction in the number of ovipositing females, number of eggs, and number of progeny per female were also observed in the houses in which both Olyset Duo and PPF-impregnated nets were used. This is the first field study showing the high sterilizing efficacy of PPF against wild pyrethroid-resistant An. gambiae s.s. population. In addition, we recognized the necessity of combined use of permethrin with PPF, in order to reduce the risk of mosquito bites and provide a level of personal protection. Further studies on wild pyrethroid-resistant mosquito populations such as An. arabiensis and An. funestus s.s. would provide more information on the practical use of the PPF-impregnated bed nets.
拟除虫菊酯抗性正成为病媒控制项目的一个主要问题，因为目前几乎没有适合替代拟除虫菊酯的化学药剂，因为用于蚊帐时，该杀虫剂必须具有低哺乳动物毒性以及对蚊子的高活性。吡丙醚（PPF）是保幼激素类似物（JHM）组中活性最高的化学药剂之一。使用PPF使蚊子绝育可能是一种针对拟除虫菊酯抗性疟疾媒介的潜在控制措施。我们研究了两种PPF浸溃蚊帐——1%PPF浸溃蚊帐和1%PPF+2%氯菊酯浸溃蚊帐（Olyset Duo）——对肯尼亚西部冈比亚按蚊指名亚种的拟除虫菊酯抗性野生种群的绝育效果。在使用PPF浸溃蚊帐的房屋中，采吸血蚊3天后观察到高死亡率，这表明PPF对接触蚊帐的蚊子寿命有影响。在使用Olyset Duo蚊帐和PPF浸溃蚊帐的房屋中，还观察到产卵雌蚊数量、卵数量和每只雌蚊后代数量减少。这是第一项显示PPF对野生拟除虫菊酯抗性冈比亚按蚊指名亚种具有高绝育效力的现场研究。此外，我们认识到有必要将氯菊酯与PPF联合使用，以降低蚊虫叮咬风险并提供一定程度的个人防护。对诸如阿拉伯按蚊和嗜人按蚊指名亚种等野生拟除虫菊酯抗性蚊虫种群的进一步研究将为PPF浸溃蚊帐的实际应用提供更多信息。
