Resistance to carbosulfan in Anopheles gambiae from Ivory Coast, based on reduced sensitivity of acetylcholinesterase

Abstract

Abstract. Resistance to carbosulfan, a carbamate insecticide, was detected in field populations of the malaria vector mosquito Anopheles gambiae Giles (Diptera: Culicidae) from two ecologically contrasted localities near Bouake , Ivory Coast: rural M'be with predominantly M form of An. gambiae susceptible to pyrethroids; suburban Yaokoffikro with predominantly S form of An. gambiae highly resistant to pyrethroids (96% kdr). The discriminating concentration of 0.4% carbosulfan (i.e. double the LC 100 ) was determined from bioassays with the susceptible An. gambiae Kisumu strain. Following exposure to the diagnostic dosage (0.4% carbosulfan for 1 h), mortality rates of female An. gambiae adults (reared from larvae collected from ricefields) were 62% and 29% of those from M'be and Yaokoffikro, respectively, 24 h post-exposure. Exposure for 3 min to netting impregnated with the operational dosage of carbosulfan 200 mg/m 2 gave mortality rates of 88% of those from M'be and only 12.2% for Yaokoffikro. In each case the control untreated mortality rate was insignificant. Biochemical assays to detect possible resistance mechanism(s) revealed the presence of insensitive AChE in populations of An. gambiae at both localities, more prevalent in the S form at Yaokoffikro than in M form at M'be , as expected from bioassays results. Our study demonstrates the need to monitor carbamate resistance among populations of the An. gambiae complex in Africa, to determine its spread and anticipate vector control failure if these insecticides are employed.

Evaluation of novel carbamate insecticides for neurotoxicity to non-target species

“…Carbamates have been widely applied onto bednets and as indoor sprays in malarial control in recent years and achieved some positive results Djè nontin et al 2009;Djè nontin et al 2010), but the increasing number of reports finding carbamate-and organophosphate-resistant A. gambiae stains requires the discovery of alternative anticholinesterases (Boon et al 2008;Corbel et al 2003;Mostafa and Allam 2001;N'Guessan et al 2003). In the following pages, brief introduction will be given on the structure, pharmacodynamics, pharmacokinetics, and toxicity of carbamate and organophosphate insecticides.…”

Mixture for Controlling Insecticide-Resistant Malaria Vectors

“…gambiae population of mosquitoes (mainly composed of the molecular S form) carrying 2 resistance genes for pyrethroids and OPs/carbamates (kdr and Ace1 R , respectively), at moderate to high frequency. The effi cacy of the mixtures was due to strong synergism between the 2 active ingredients, as (29) and the carbamate carbosulfan (29,30) were also recently tested on nets to verify their effi cacy in terms of induced deaths against pyrethroid-resistant populations of An. gambiae mosquitoes and were found to be as lethal as deltamethrin, lambda cyalothrin, or permethrin.…”

Anopheline Mosquitoes and the Malaria Scourge

“…Twelve insecticides from four classes (organochlorines, organophosphates, carbamates and pyrethroids) have been recommended for IRS [46,47], but only pyrethroids have been approved for treating bed nets. Since the mid-1950s, there have been numerous reports of reduced Anopheles susceptibility to DDT, malathion, fenithrotion, propoxur and bendiocarb, and resistance to all four classes of insecticides has been found in Anopheles species in different parts of Africa [48,49]. A much more recent development is that of…”