Antibiotic-Mediated Microbiota Depletion of Aedes aegypti Gut Bacteria Modulates Susceptibility to Entomopathogenic Fungal Infection and Modifies Developmental Factors

Entomopathogenic fungi are promising alternatives to synthetic insecticides for the control of vector species, notably the arbovirus vector, Aedes aegypti. The influence of intrinsic mosquito midgut microbiota on host susceptibility to fungal infection and subsequent physiological processes remains poorly understood. Here we treated female Ae. aegypti with the broad-spectrum antibiotic carbenicillin to reduce gut bacterial populations, then exposed them to Metarhizium anisopliae conidia. Female Ae. aegypti offered carbenicillin and then sprayed with fungi had significantly lower survival rates (38.9% ± 1.15) compared to non-antibiotic-treated mosquitoes sprayed with fungus (68.9% ± 0.58). To monitor the kinetics of microbial community recovery, mosquitoes were challenged with conidia at 0, 3, 6, and 9 days following antibiotic removal from the diet. Reduced survival persisted through the 6-day period (survival rates 37.8% to 45.6%), with a significant increase in survival observed 9 days post-antibiotic removal (58.9% vs. control 63.3%), which coincided with recovery of gut bacterial populations. Additionally, antibiotic and fungal treatments reduced egg production, larval eclosion, and pupal formation. These results demonstrate that gut bacteria contribute to mosquito defense against fungal pathogens and support normal reproductive and developmental functions. Understanding the interplay between gut microbiota and entomopathogenic fungi may enhance biological control approaches.