RNAi-based attractive targeted sugar baits

The development of transformative, environmentally friendly, cost-effective new mosquito control interventions is critical for preventing arboviral diseases. Attractive targeted sugar baits (ATSBs), a new paradigm for mosquito control, exploit the sugar feeding behavior of male and female mosquitoes that are lured to feed on a sugar bait which contains an insecticide. We have developed a new class of environmentally-friendly mosquito-specific interfering RNA pesticides (IRPs) that may help combat rising incidences in pesticide resistance and enhance existing ATSB technology. These IRPs have 25 bp target sites that are conserved in many species of disease vector mosquitoes, but which are not found in humans or other non-target organisms. Saccharomyces cerevisiae (yeast) strains for cost-effective IRP production were developed. Recent laboratory trials confirmed that these yeast IRP strains can be used directly as mosquito-attracting adulticidal agents in ATSBs. The activity of multiple different yeast IRPs was confirmed in sucrose-based ATSB trials that were conducted on Aedes and Culex female mosquitoes. Target gene silencing and the IRP modes of action were verified in the Aedes aegypti brain. Although the yeast-based ATSBs were toxic to multiple species of mosquitoes, the insecticides were not toxic to select non-target arthropods. The yeast IRP-ATSBs are now being assessed in semi-field trials, and efforts to scale yeast production for larger field studies and potentially for commercial production are ongoing. The results of these studies suggest that yeast IRP-ATSBs could benefit integrated mosquito control programs.