Impact of larval diet on fitness outcomes of Aedes aegypti mosquitoes infected with wAlbB and wMelM.

Abstract

Background: Releases of Wolbachia-infected Aedes aegypti are being used to effectively control diseases caused by arboviruses, such as dengue. A well-balanced larval diet is essential for producing Wolbachia-infected mosquitoes with optimal fitness for release.

Methods: In this study, four diets with varying protein-to-carbohydrate ratios were tested with three Ae. aegypti lines (carrying the wAlbB, wMelM Wolbachia infections or uninfected) to identify optimal diets for larval rearing on the basis of diet allocations ranging from 0.4 to 3.2 mg/larva/day. The diets were selected on the basis of a review of existing literature and are characterized by progressively increasing protein and decreasing carbohydrate content: diet 1 (Pd) was based on plant-based protein (low protein and high carbohydrate), diet 2 (Kd) was based on animal-based protein (moderate protein and high carbohydrate), diet 3 (Fd) involved Hikari fish food (high protein and moderate carbohydrate), and diet 4 (IAEA) followed a widely used very-high-protein and low-carbohydrate diet developed by the International Atomic Energy Agency (IAEA). The optimal concentration for each diet was determined using a fitness index that incorporated pupation success, fecundity, hatch proportion and development time.

Results: The optimal dietary allocations for diets 1-4 were 1.6, 1.2, 1.2 and 0.8 mg/larva/day, respectively, regardless of Wolbachia status. There was a consistent significant positive relationship between female wing length and fecundity in wAlbB (r² = 0.881), wMelM (r² = 0.329), and uninfected (r² = 0.886) mosquitoes. Diet 3 (Fd) at optimal food allocation reduced a fitness cost commonly associated with the wAlbB line compared with the uninfected line when provided at the optimal concentration. The wMelM line showed a persistently low fecundity regardless of diet and concentration.

Conclusions: These findings highlight the importance of an appropriate larval diet and dietary allocations in optimizing mosquito fitness for Wolbachia-based vector control programs. Further research into dietary composition, gut microbial interactions and Wolbachia associations could refine larval nutrition strategies, enhancing the effectiveness of mass-rearing for release programs.