Author Description

In Chapter 2, I outlined systematic investigations of different concentrations of PMD and transfluthrin as potential spatial repellents applied on eave fabric and their protective efficacy on unprotected persons in the peri-domestic space outdoors. These outcomes were quantified in semi field systems in western Kenya using insectary-reared Anopheles arabiensis. Two concentrations of PMD tested did not offer any protection against outdoor biting, while two concentrations of transfluthrin were both protective, with the higher concentration offering more protection than the lower one. These results confirmed the spatial repellency effect of transfluthrin on outdoor-biting An. arabiensis. Supplementation of transfluthrin using an MB5-baited Suna trap did not have any additional effect on the protective efficacy seen with the spatial repellent alone. The MB5-baited Suna trap supplemented with either carbon dioxide or 2-butanone on its own did not divert mosquitoes from an unprotected human seated 2.5 m away from the trap, confirming that an unprotected human remains more attractive to host-seeking malaria vectors than to a trap baited with a synthetic lure. Utilization of 2-butanone as a supplement to replace carbon dioxide in the MB5-baited Suna trap was not as effective as mosquito recapture rates of a trap supplemented with carbon dioxide were significantly higher, indicating that 2-butanone is not an adequate carbon dioxide mimic in attracting An. arabiensis. Quantification of the airborne concentrations of the push-pull chemical components showed that transfluthrin was detectable within a 5 m radius from the eave fabrics applied on experimental houses, with higher concentrations detected nearest the house and closer to the ground, with reducing concentrations further away and at distances higher above ground.