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

Background Releases of Aedes aegypti infected with Wolbachia are being used to effectively control diseases related to arboviruses in some settings. 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 Aedes aegypti lines (carrying the w AlbB, w MelM infections or uninfected) to identify optimal diets for larval rearing based on diet allocations ranging from 0.4 to 3.2 mg/larva/day. The diets were selected based on 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, high carbohydrate), Diet 2 (Kd) was based on animal-based protein (moderate protein, 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 to 4 were 1.6, 1.2, 1.2, and 0.8 mg per larva per day, respectively, regardless of Wolbachia status. There was a consistent significant positive relationship between female wing length and fecundity in w AlbB (r ²  = 0.881), w MelM (r ²  = 0.329), and uninfected (r ²  = 0.886) mosquitoes. Diet 3 (Fd) reduced a fitness cost commonly associated with the w AlbB line compared to the uninfected line when provided at the optimal concentration. The w MelM 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.