Target of rapamycin (TOR) is necessary for the blood digestion and reproduction of Aedes albopictus

Abstract

Aedes albopictus transmits the virus through repeated blood feeding behavior and can also vertically transmit the virus to its offspring. In this study, we analyzed the expression of the TOR gene in Ae. albopictus and found that it was highest in female mosquitoes 24 h after feeding, particularly in the head and thorax. Then, we used to feed method to silence the TOR gene of female mosquitoes and make them suck blood. Silencing TOR resulted in downregulation of amino acid transporter genes SLC7A5 and SLC3A2, as well as regulatory intermediates Rheb and Frizzled-2 in other signaling pathways. In terms of midgut blood digestion, silencing TOR led to reduced glucose metabolism while affecting trypsin (TRY) and chymotrypsin (CHY) enzymes involved in midgut blood digestion, thereby delaying the process. Regarding reproduction, silencing TOR resulted in decreased expression levels of Vitellogenin 2 (Vg2) and Vg3 gene, leading to reduced Vg content in the ovary. Additionally, downstream protein synthesis-related genes 4E-binding protein (4E-BP) and S6 kinase (S6K) within the TOR pathway were affected. Although there were no significant changes observed in egg number or diameter, ovarian development cycle delay occurred along with signs of desiccation and shrinkage in some eggs. Moreover, both egg weight and hatching rate showed a significant decrease. The experimental results suggest that TOR regulates the blood digestion and reproduction process of A. albopictus by influencing post-vampire protease activity and protein synthesis, such as Vg. This provides a theoretical foundation for developing cost-effective and large-scale prevention and control measures for A. albopictus.