Small mosquitoes - large implications: Comparison of the fat body transcriptome and metabolome of adult aedes aegypti from larvae raised under different nutrition and crowding regimens

Background:  Environmental factors such as water temperature, nutrient availability, and larval density determine the outcome of postembryonic development in mosquitoes. Suboptimal temperatures, crowding, and starvation during the larval phase reduce adult mosquito size, nutrient stores and affect vectorial capacity.  In this study we compared adult female Aedes aegypti, Rockefeller strain, raised under standard laboratory conditions (Large) with those raised under crowded and nutritionally deprived conditions (Small).  We compared the transcriptome and metabolome of the major energy storage and metabolic organ, the fat body, across standard and small female Ae. aegypti before and 24 hours after blood feeding.

Results:  Analysis of fat body gene expression between the experimental groups revealed a large number of significantly differentially expressed genes.   Transcripts related to immunity, reproduction, autophagy, several metabolic pathways; including amino acid degradation and metabolism; and membrane transport were differentially expressed.  Metabolite profiling identified 60 metabolites within the fat body to be significantly affected between small and standard mosquitoes, with the majority of detected free amino acids at a higher level in small mosquitoes compared to large.  

Conclusions:  Gene expression and metabolites in the adult fat body reflect the individual post-embryonic developmental history of a mosquito larva. Changes affect nutritional storage and utilization, immunity, and reproduction.  Therefore, it is apparent that changes in larval environment due to weather conditions, nutrition availability, vector control efforts, and other factors can affect adult vectorial capacity in the field.