Modifications of the fat body of the predator Toxorhynchites theobaldi (Diptera; Culicidae) during the post-embryonic development

The fat body is the intermediary metabolism organ of insects and it is able to change its structure according to the insect nutritional demands. Toxorhynchites (Theobaldi) is useful for vector mosquito control because its larvae are predators of other mosquitoes. Nevertheless, Toxorhynchites fat body development is poorly studied. Considering this, we investigated some fat body cells or trophocytes characteristics during Toxorhynchites theobaldi (Dyar and Knab) development. The lipid droplet size increases during the larval stage (L2 to L4) and may result from lipogenesis during larval development. However, it then decreases in size during L4 to the pupal stage and increases additionally from newly-emerged to aged adult females. The protein granules are observed in pupae and, as well as lipid droplets; their enlargement may be related to adult female demands for yolk precursors. The trophocyte nuclear size also increases during larvae development. However, it decreases during metamorphosis and increases in size further during adult aging. Thus, it can be inferred that the trophocyte nuclear activity drops during metamorphosis and increases during adult aging. In conclusion, the Toxorhynchites theobaldi fat body morphology changes according to the individual developmental stage. Finally, our study provides important novel insights into Toxorhynchites theobaldi fat body development and contributes to understand this species biology.