Medical and Veterinary Entomology Unit, Institut Pasteur du Cambodge, 5 Boulevard Monivong, Phnom Penh, Cambodia.
International Pasteur Institute Network, Institut Pasteur, Paris, France.
Parasit Vectors. 2022 Jan 31;15(1):44. doi: 10.1186/s13071-022-05156-3.
Dengue fever is a major public health concern in Cambodia, with thousands of cases every year in urban, suburban and rural areas of the country. The main vector of dengue fever in Cambodia is Aedes aegypti. The organophosphate larvicide temephos and adulticides belonging to the pyrethroid family have been widely used for decades by public health authorities to fight dengue vectors, but resistance of Ae. aegypti to these insecticides has been previously described for Cambodia.
In order to adapt the vector control strategy presently used in Cambodia, we tested 14 adulticides belonging to the carbamate, organochlorine, organophosphate, and pyrethroid insecticide families and three larvicides [temephos, spinosad and Bacillus thuringiensis ser. israelensis (Bti)] belonging to three different insecticide families (organophosphates, spinosyns and entomopathogenic bacteria). The standard procedures used here to test the adults and larvae of an Ae. aegypti population from Phnom Penh followed World Health Organization guidelines.
For adults, high mortality rates were observed with carbamate, organophosphate and organochlorine (with the exception of dichlorodiphenyltrichloroethane) insecticides (i.e. between 87.6 and 100%), while low mortality rates were observed with all of the tested pyrethroid insecticides (i.e. between 1 and 35%). For larvae, no resistance against Bti was detected [resistance ratio (RR < 1.6)], but moderate resistance was observed for temephos and spinosad (RR < 5.6).
The results of this study indicate that (i) Bti should be considered a serious alternative to temephos for the control of Ae. aegypti larvae; and (ii) the carbamate adulticides propoxur and bendiocarb should be employed instead of the widely used pyrethroid insecticides for the control of adult Ae. aegypti on land under mosaic farming and crop rotation in Cambodia, as the insects were found to be resistant to the latter types of insecticide. Research focusing on insecticide resistance and innovative and effective vector control strategies should be undertaken as a public health priority in Cambodia.
登革热是柬埔寨的一个主要公共卫生问题，每年在该国城市、郊区和农村地区都有数千例病例。柬埔寨的登革热主要传播媒介是埃及伊蚊。几十年来，公共卫生部门一直广泛使用有机磷杀幼虫剂涕灭威和属于拟除虫菊酯类的杀成虫剂来防治登革热媒介，但此前已描述过柬埔寨埃及伊蚊对这些杀虫剂的抗药性。
为了调整目前在柬埔寨使用的病媒控制策略，我们测试了 14 种属于氨基甲酸酯、有机氯、有机磷和拟除虫菊酯类杀虫剂家族的杀成虫剂，以及 3 种属于 3 种不同杀虫剂家族（有机磷、多杀菌素和苏云金芽孢杆菌以色列亚种（Bti））的杀幼虫剂[涕灭威、多杀菌素和苏云金芽孢杆菌以色列亚种（Bti）]。这里用于测试来自金边的埃及伊蚊种群成虫和幼虫的标准程序遵循世界卫生组织的准则。
对于成虫，氨基甲酸酯、有机磷和有机氯（除了滴滴涕）杀虫剂（即 87.6%至 100%）表现出高死亡率，而所有测试的拟除虫菊酯杀虫剂（即 1%至 35%）表现出低死亡率。对于幼虫，未检测到对 Bti 的抗性（抗性比（RR）<1.6），但对涕灭威和多杀菌素表现出中度抗性（RR<5.6）。
本研究结果表明，（i）Bti 应该被视为控制埃及伊蚊幼虫的涕灭威的严重替代品；（ii）在柬埔寨的马赛克农业和轮作下，应该使用氨基甲酸酯类杀成虫剂丙硫克百威和丁硫克百威代替广泛使用的拟除虫菊酯类杀虫剂来控制成年埃及伊蚊，因为这些昆虫对后者类型的杀虫剂具有抗药性。作为公共卫生的优先事项，柬埔寨应开展有关杀虫剂抗性和创新有效的病媒控制策略的研究。
