Aïzoun Nazaire, Ossè Razaki, Azondekon Roseric, Alia Roland, Oussou Olivier, Gnanguenon Virgile, Aikpon Rock, Padonou Gil Germain, Akogbéto Martin
Parasit Vectors. 2013 May 20;6:147. doi: 10.1186/1756-3305-6-147.
The detection of insecticide resistance in natural populations of Anopheles vectors is absolutely necessary for malaria control. In the African region, the WHO insecticide susceptibility test is the most common method for assessing resistance status. In order to search for a simple, rapid and more reliable technique in the assessment of insecticide resistance in malaria vectors, we compared the WHO tests with the CDC bottle bioassay in the Ouemé province of southern Benin where insecticide resistance has been widely reported.
Larvae and pupae of Anopheles gambiae s.l. mosquitoes were collected from the breeding sites in Ouemé. WHO and CDC susceptibility tests were conducted simultaneously on unfed female mosquitoes aged 2-5 days old. WHO bioassays were performed with impregnated papers of deltamethrin (0.05%) and bendiocarb (0.1%), whereas CDC bioassays were performed with stock solutions of deltamethrin (12.5 μg per bottle) and bendiocarb (12.5 μg per bottle). PCR techniques were used to detect species, Kdr and Ace-1 mutations. CDC biochemical assays using synergists were also conducted to assess the metabolic resistance.
A slight decrease in mortality rates was observed with 97.95% and 98.33% obtained from CDC and WHO bioassays respectively in populations of mosquitoes from Adjara and Dangbo. PCR revealed that all specimens tested were Anopheles gambiae s.s. The Kdr mutation was found at high frequency in all populations and both the Kdr mutation and mono-oxygenase enzymes were implicated as mechanisms of pyrethroid resistance in An. gambiae from Misserete.
This study emphasizes that both WHO and CDC bioassays give similar results with regards to the susceptibility of mosquitoes to insecticides in southern Benin. There were complementarities between both methods, however, some specificity was noted for each of the two methods used. Both Kdr and metabolic mechanisms were implicated in the resistance.
检测按蚊媒介自然种群中的杀虫剂抗性对于疟疾控制绝对必要。在非洲地区，世卫组织杀虫剂敏感性试验是评估抗性状况最常用的方法。为了寻找一种在评估疟疾媒介杀虫剂抗性方面简单、快速且更可靠的技术，我们在贝宁南部的韦梅省对世卫组织试验和疾控中心瓶式生物测定法进行了比较，该省已广泛报道存在杀虫剂抗性。
冈比亚按蚊复合组的幼虫和蛹从韦梅的繁殖地采集。对2至5日龄未进食的雌蚊同时进行世卫组织和疾控中心敏感性试验。世卫组织生物测定法使用溴氰菊酯（0.05%）和残杀威（0.1%）浸渍纸进行，而疾控中心生物测定法使用溴氰菊酯原液（每瓶12.5微克）和残杀威原液（每瓶12.5微克）进行。采用聚合酶链反应技术检测蚊种、Kdr和Ace-1突变。还进行了使用增效剂的疾控中心生化测定以评估代谢抗性。
在来自阿贾拉和当博的蚊虫种群中，疾控中心和世卫组织生物测定法的死亡率分别为97.95%和98.33%，死亡率略有下降。聚合酶链反应显示，所有测试标本均为冈比亚按蚊指名亚种。在所有种群中均发现Kdr突变频率很高，Kdr突变和单加氧酶均被认为是冈比亚按蚊对拟除虫菊酯产生抗性的机制。
本研究强调，在世卫组织和疾控中心生物测定法对贝宁南部蚊虫对杀虫剂的敏感性方面给出了相似结果。两种方法之间存在互补性，然而，所使用的两种方法各自都有一些特异性。Kdr和代谢机制均与抗性有关。
