Experimental and molecular genetic analysis of the impact of pyrethroid and non-pyrethroid insecticide impregnated bednets for mosquito control in an area of pyrethroid resistance

Abstract

Experimental huts in Côte d'Ivoire were used to evaluate the pyrethroid alphacypermethrin, the non-ester pyrethroid etofenprox, the organophosphate pirimiphos-methyl and the carbamate carbosulfan on bednets against pyrethroidresistant Anopheles gambiae Giles. To test for selection for the resistance gene by the treated nets, A. gambiae collected live or dead from the huts were kept and analysed for the presence of the kdr gene using a new polymerase chain reaction followed by sequence-specific oligonucleotide probing (PCR-SSOP) for kdrgenotyping. Deliberately holed bednets freshly treated with pirimiphos-methyl or carbosulfan caused over 90% kill of A. gambiae s.s. and Culex spp. However, the mortality with alpha-cypermethrin or etofenprox treated nets was similar to that with untreated nets. Bloodfeeding of A. gambiae s.s. on the sleepers under the nets was only significantly reduced by alpha-cypermethrin and carbosulfan. Tests of the residual activity of the bednets after seven months showed that pirimiphosmethyl had lost its efficacy while carbosulfan still performed well. Once again the pyrethroid treated nets gave similar results to the untreated nets. Selection for the kdr-allele by alpha-cypermethrin and etofenprox, but not by carbosulfan, was indicated by PCR-SSOP genotyping of mosquitoes. Thus carbamates such as carbosulfan, or organophosphates of longer persistence than pirimiphos-methyl and of low mammalian toxicity, would seem to be a promising alternative to be used on bednets, particularly in areas of pyrethroid resistance.

Efficacy of Permethrin-Treated Uniforms in Combination with DEET Topical Repellent for Protection of French Military Troops in Côte d’Ivoire

“…The excellent conditions under which this study was carried out owe much to the experience of the Institut Pierre Richet, which did numerous studies using experimental huts to assess the efÞcacy of impregnated cloth and repellents (Darriet et al 1999, Kolaczinski et al 2000.…”

Phenotypic effects of concomitant insensitive acetylcholinesterase ( ace-1 R ) and knockdown resistance ( kdr R ) in Anopheles gambiae : a hindrance for insecticide resistance management for malaria vector control

“…Carbamates and organophosphates have shown a relatively good efficacy in ITNs and IRS [42][43][44][45] with high mortality of pyrethroids-resistant [46] An. gambiae s.s in Côte d'Ivoire [47]. However a particular concern for the use of carbamates and organophosphates is that resistance to these insecticides is already present in some An.…”

Efficacy of ACTELLIC 300 CS, Pirimiphos Methyl, for Indoor Residual Spraying in Areas of High Vector Resistance to Pyrethroids and Carbamates in Zambia

“…The organophosphates, carbamates, and pyrethroids that are ideal for IRS are mostly shorter-lived and more expensive than DDT. Pirimiphos methyl is an organophosphate that has proved to be efÞcacious for IRS (Miller et al 1991, Kolaczinski et al 2000. The WHO Pesticide Evaluation Scheme (WHOPES) has evaluated a novel pirimiphos methyl capsule suspension (CS) formulation, ACTELLIC 300 CS (0-2-diethylamino-6-methylpyrimidin-4-yl 0, 0-dimethylphosphorothioate, supplied by Syngenta Crop Protection AG, Basel, Switzerland), an organophosphate with extended residual performance (WHO 2007).…”