Exploring alternative insecticide delivery options in a “Lethal House Lure” for malaria vector control

Abstract The In2Care® EaveTube is a house modification designed to block and kill malaria mosquitoes using an electrostatic netting treated with insecticide powder. A previous study demonstrated prolonged duration of effective action of insecticide-treated electrostatic netting in a semi-field setting. As part of a cluster randomized controlled trial (CRT) of the EaveTube intervention in Cote d’Ivoire, we investigated the residual efficacy of a pyrethroid insecticide deployed in Eave Tubes under village condition of use. We also explored the scope of using existing malaria control technologies including LLINs and IRS as alternative methods to deliver insecticides in the lethal house lure. The efficacy of beta-cyfluthrin was evaluated using the “eave tube bioassay” and was found to be relatively short-lived in the field during the CRT, with mortality of pyrethroid resistant Anopheles gambiae mosquitoes declining below 80% after 4 months. The impact (mosquito mortality) of PVC tubes coated with pirimiphos methyl was similar to that of beta-cyfluthrin treated insert (66.8 vs 62.8%) in release-recapture experiments in experimental huts. Efficacy was significantly lower with all the LLINs tested; however, the roof of PermaNet 3.0 induced significantly higher mosquito mortality (50.4%) compared to Olyset Plus (25.9%) and Interceptor G2 (21.6%) LLINs. The new delivery methods showed a rapid decline in efficacy over time with mortality decreasing below 50% within 2 months in residual activity bioassays. None of the current products appeared superior to the powder treatments but as with the powders, further research and development on formulations and doses are required.