Differences in bacterial load in Aedes aegypti larval rearing water containing diverse microbial communities

Abstract

Understanding how Aedes aegypti larvae interact with their microbial environment is critical for mosquito control strategies such as sterile insect technique (SIT). The effectiveness of SIT relies on rearing high quality males that are sterilized and released into the wild where they must successfully compete for mates. Nutritional intake is key to Ae. aegypti mosquito fitness, and the larval microbiota is a primary component of larval nutrition. This study examines whether environmental bacterial loads differ when larvae are presented with field-derived communities of bacterial isolates as opposed to an artificially simplified microbiota of just E. coli. We monitored changes in bacterial load over time in rearing water with and without larvae. Our results show that in the presence of larvae, microbial communities significantly influence aquatic bacterial load (p=0.00057), with effects varying across different days of larval development as indicated by a significant interaction between treatments and days (p=0.02). In the absence of larvae, microbial communities used for inoculation significantly influence aquatic bacterial load (p=7.87x10-5). Days from inoculation also had a significant main effect (p=0.0033), indicating that bacterial load changed across timepoints. However, the interaction between treatment and days was not significant (p=0.1944), demonstrating that although bacterial load differed among days, the pattern of change over time was similar across treatments. Altogether, these findings show that variation in bacterial load across treatments likely reflects differences in how each community responds to the rearing environment and the effects of larval-mediated processes. Compared to the no-larvae treatment, where bacterial load follows a typical growth-decline trajectory, treatments with larvae demonstrate altered patterns consistent with nutrient enrichment and larval feeding. Although we did not characterize the specific bacterial taxa present, and therefore cannot infer underlying community dynamics, the patterns observed among treatments indicate that communities differ in their ability to utilize available nutrients and maintain abundance in the presence of larval feeding. Through better understanding how bacterial composition affects mosquito development, we can find better ways to optimize mass-rearing strategies and improve male mosquito life history traits.No embargoAcademic Major: Biolog