RT Journal Article
SR Electronic
T1 Small-scale field testing of Alpha-cypermethrin water-dispersible granules in comparison with the recommended wettable powder formulation for indoor residual spraying against malaria vectors in Benin
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 204651
DO 10.1101/204651
A1 Nicolas Moiroux
A1 Armel Djenontin
A1 Barnabas Zogo
A1 Aziz Bouraima
A1 Ibrahim Sidick
A1 Olivier Pigeon
A1 Cédric Pennetier
YR 2017
UL http://biorxiv.org/content/early/2017/12/22/204651.abstract
AB Backgroud Pyrethroids are the most common class of insecticide used worldwide for indoor residual spraying (IRS) against malaria vectors. Water-dispersible granules (WG) are a pyrethroid formulation to be applied after disintegration and dispersion in water with less risks of inhalation than using the usual wettable powder (WP) formulation. The objective of this small-scale field study was to evaluate efficacy and duration of insecticidal action of a new alpha-cypermethrin WG (250g a.i./Kg) against susceptible Anopheles gambiae in comparison with the WHO reference product (alpha-cypermethrin WP, 50g a.i./Kg) on the most common indoor surfaces in Benin.Methods Both formulations were applied at two target-dose concentrations in houses made of mud and cement in the Tokoli village in southern Benin. We measured the applied dose of insecticide by chemical analysis of filter paper samples collected from the sprayed inner walls. We recorded An. gambiae mortality and knock-down rates every 15 days during 6 months using standard WHO bioassays.Results The alpha-cypermethrin WG formulation did not last as long as the WP formulation on both surfaces. The difference is higher with the 30mg/m2 concentration for which the WP formulation reached the 80% mortality threshold during 2 months on the mud-plastered walls (3 months on cement) whereas the WG formulation last only one month (2 months on cement).Conclusions The new WG formulation has a shorter efficacy than the WHO recommended WP formulation. In this trial, both the WG and WP formulations had low durations of efficacy that would need at least two rounds of spray to cover the entire transmission season.List of abbreviationsIRDinstitut de Recherche pour le DéveloppementCRECCentre de Recherche en Entomologie de CotonouIRSindoor Residual SprayingWGWater-dispersible GranulesWPWettable PowderWHOWorld Health OrganisationWHOPESWorld Health Organisation Pesticides Evaluation SchemaNMCPNational Malaria Control ProgramITNinsecticide Treated Neta.i.active ingredientKDKnock DownCIConfidence interval