Soda-baited RNAi yeast insecticides as effective Attractive Targeted Sugar Baits (ATSBs) for mosquito control.

BACKGROUND: Attractive Targeted Sugar Baits (ATSBs) are a promising, environmentally friendly approach for mosquito control, but the direct field application, scalability and long-term effectiveness of ATSBs across diverse mosquito species remain significant challenges. METHODOLOGY/PRINCIPAL FINDINGS: We assessed the efficacy of a genetically engineered RNA interference (RNAi) yeast strain (Sh.463) formulated in three sugar baits: soda (Coca-Cola), 10% sucrose, and a commercial mosquito bait (BaitStab), on Aedes, Anopheles and Culex mosquitoes. All RNAi yeast bait formulations induced significantly higher mean mortality (87-100%) compared to the control groups (0-9%), but RNAi yeast-soda baits resulted in significantly higher mortality rates of 94-100% recorded across all mosquito species. Additionally, to assess the competitiveness of the RNAi yeast-soda bait to other tropical sugar sources, semi-field choice assays were conducted in Trinidad, West Indies using competing flowering plants and fruits typically found in residential environments. The RNAi yeast-soda ATSB continued to perform well in the presence of many competing floral and fruit sugar sources during both Aedes albopictus and Culex quinquefasciatus trials, but the presence of several fruits and flowers did significantly reduce Sh.463-induced mosquito mortality with the degree of competitive deterrence being heavily modulated by mosquito species, sex, and floral resource, suggesting that further field testing will be necessary. The residual activity of the Sh.463 + soda formulation was retained for at least 14 months, with sustained 100% mortality in C. quinquefasciatus and 93-100% mortality in Aedes aegypti, Anopheles gambiae and Anopheles stephensi. The RNAi yeast-soda ATSB also performed well in semi-field studies performed with a prototype soda bottle feeder. CONCLUSIONS/SIGNIFICANCE: This study demonstrates the potential of soda-baited RNAi yeast as a potent, long-lasting, and scalable platform for ATSB-based mosquito control as a component of integrated vector management programs.