Optimizing a Gravid Mosquito Resting Box to Enhance Auto-dissemination of Larvicides under Semi-Field Conditions in Western Kenya

Abstract

Malaria control strategies are challenged by emergence of insecticide resistance and behavioral changes of the vector. New vector management tools are required to avert control failure. The aim of this study was to optimize a mosquito resting box that act as contamination station for auto-dissemination of novel chemicals by female Anopheles gambiae to their oviposition sites. In this study, cotton fabrics (red, black, blue, white), circular & rectangular boxes of different sizes were tested for resting preference. Optimal box size and shape, aligned with most attractive colour, was dusted with red fluorescent dye (larvicide proxy). Two artificial oviposition sites were set up in a screen house, one of which was treated with Cedrol, the other had tap water only. Two to three days old bloodfed mosquitoes were used for resting preference whereas gravid females were used for auto-dissemination experiments. A high resting preference was observed in red and black fabrics (28.08 ± 3.211), (28.00 ±3.922) respectively, compared to white (4.67±0.890). Choice of colour was found to influence mosquito landing (P=0.000<0.05). With the choice of most preferred colour, the rectangular black box (45m×30m×45m) attracted high proportion (60%) of mosquitoes. The box effectively transferred dye to the resting mosquitoes and to the oviposition site, with 67% visited oviposition site, having dye on their body. These results reveal that the black rectangular box attracted adult blood-fed and gravid mosquitoes high enough showing great potential as future malaria vector control and/or sampling tool, and is recommended for further field-based evaluation.