Effects of Dietary Sugars and Sugar Alcohols on Mortality and Thermal Tolerance in Culex quinquefasciatus and Aedes aegypti

Abstract

Aedes aegypti (L. 1762), the yellow fever mosquito, and Culex quinquefasciatus Say 1823, the southern house mosquito, are prevalent in tropical and subtropical areas worldwide and are responsible for the spread of a number of devastating diseases to humans and livestock. The development of new control methods, as well as continued study of mosquito biology, is vital for improving human health. This study aimed to examine the efficacy of sugar alcohols as a novel means for mosquito control, as well as how sugar alcohols and other factors are involved in thermal tolerance in mosquitoes. No-choice tests with the sugar alcohols erythritol, sorbitol, and xylitol resulted in significant mortality in at least one species, with erythritol resulting in the highest mortality. A two-choice test between sucrose with or without added erythritol showed no significant preference between the two in either Ae. aegypti or Cx. quinquefasciatus. Based on our findings, erythritol and other sugar alcohols have good potential as novel mosquito toxins, and further study should be conducted into the efficacy of deployment in the field. Thermal tolerance assays demonstrated that the consumption of sugar alcohols does not improve cold tolerance in Cx. quinquefasciatus, but that consumption of mannitol can decrease heat tolerance. We observed similar levels of cold tolerance between all diets tested. However, we found that Cx. quinquefasciatus was inherently significantly more cold tolerant than Ae. aegypti, while Ae. aegypti had improved heat tolerance compared to Cx. quinquefasciatus. There were no differences in thermal tolerance between sexes within either species. Our results suggest that although dietary factors such as sugar alcohols and sugars may play a role in thermal tolerance in mosquitoes, there are likely physiological and genetic factors that can have a greater influence on the limits of thermal tolerance within a species.