Potential of repurposed agricultural ingredients in propylene glycol emulsions as oral toxicants for control of adult mosquitoes (Diptera: Culicidae)

Mosquito control operations have limited options available for adult mosquito reduction. Untapped alternatives exist in adjacent pest-management industries, but translation and validation for various technologies is still ongoing. The attractive targeted sugar bait (ATSB) strategy is a formulation platform that is amenable to toxicants not otherwise widely used for adult mosquito control techniques and equipment. To find fast-acting, effective toxicants for ATSB, choice assays were conducted using fipronil, spinosyn, dinotefuran, clothianidin, imidacloprid, bifenazate, indoxacarb, abamectin, and λ-cyhalothrin against Aedes aegypti (L.) (Diptera: Culcidae) as a model system. Active ingredients were emulsified in propylene glycol, a secondary toxicant and formulation aid in ATSB, and sucrose solution. Treatments were presented in tandem with unadulterated 10% sucrose in all assays. In both 24-h mortality and fecal droplet analysis, indoxacarb was ingested similarly as often as the sugar water-only control group and yielded the overall lowest mortality. Imidacloprid, λ-cyhalothrin, and abamectin were all readily ingested, and in some cases the fecal droplet analysis indicated bias towards consumption of the treated sugar solutions. Mortality in the first 24 h was over 95% for the aforementioned toxicants, supporting that they both kill in limited time and have a suitable palatability or repellency response profile with mosquitoes. But imidacloprid and λ-cyhalothrin (resistance) and imidacloprid (pollinators) have roadblocks for use in ATSB because of potential nontarget impact to pollinators and prevalent insecticide resistance issues. However, abamectin appears to be a promising ingredient for future ATSB formulations to establish quick vector interruption and improve insecticide class variety for resistance management.