Aedes aegypti (L.) and Anopheles stephensi Liston (Diptera: Culicidae) Susceptibility and Response to Different Experimental Formulations of a Sodium Ascorbate Toxic Sugar Bait.

Attractive toxic sugar baits (ATSBs) require target insects to locate, orient toward, and feed on an insecticidal sugar solution to control populations. Formulating these baits with different attractants and phagostimulants can increase their efficacy by causing insects to choose the ATSB over competing natural sugar sources, and to ingest more of the bait solution. We tested formulations of a 20% sodium ascorbate (SA) ATSB solution using different sugars, adenosine triphosphate (ATP), gallic acid, and six plant volatile compounds to determine their effect on adult Aedes aegypti (L.) and Anopheles stephensi Liston mortality. Baits formulated with fructose or sucrose had no effect on either species, neither did the addition of ATP. Gallic acid increased the survival of Ae. aegypti. Four of the six volatile compounds increased mortality in at least one species. We also examined An. stephensi response to baits formulated with each of the six volatile compounds. Anisaldehyde significantly increased the number of mosquitoes responding toward the SA-ATSB, but increasing the amount had no effect. Addition of anisaldehyde also significantly increased An. stephensi feeding rates on the SA-ATSB, though mosquitoes will avoid the toxic bait if a nontoxic sugar source is available. Formulation of SA-ATSBs with synthetic blends of attractive compounds can increase bait efficacy and consistency, though further research is needed to assess their performance in the field in the presence of natural sugar sources.