Abstract
The emergence of insecticide resistance among malaria vector populations poses a significant threat to existing malaria vector control tools. This phenomenon necessitates an increased pace of developing and deploying new effective compounds in insecticides for vector control. Therefore, this study investigated the comparative performance of newly formulated indoor residual spray compounds, Klypson 500WG (Clothianidin alone) and 2GARD-WP (a mixture of Clothianidin 50% and Deltamethrin 6.25%) against An. gambiae in the lower Moshi area of the rural Moshi district, Tanzania. Before the wall cone bioassay tests, the susceptibility of field-collected adult An. gambiae s.l. to 0.75% Permethrin, 2% Klypson 500WG, 0.05% Deltamethrin, and 0.25% Pirimiphos-methyl was assessed following WHO procedures. For the cone-bioassay testing, 160 houses were randomly selected and sprayed with Klypson 500WG and 2GARD-WP. For the walls sprayed with Klypson 500WG and 2GARD-WP, the knockdown rate of Anopheles gambiae after 60 min of exposure over six months ranged from 70% to 98%, with mortality rates after 24 to 168 h consistently exceeding 90% across all villages and wall types throughout the six months. The susceptibility of wild-collected mosquitoes to Pirimiphos-Methyl, Permethrin, Deltamethrin, and Klypson 500WG was 61, 81, 86, and 93%, respectively. These findings suggest that Klypson 500WG and 2GARD-WP are suitable alternative insecticides that can be incorporated in the vector control toolbox used for malaria control.