Aspirin Inhibition of Prostaglandin Synthesis Impairs Mosquito Egg Development

Several endocrine signals mediate mosquito egg development, including 20-hydroxyecdysone (20E). This study reports on prostaglandin E(2) (PGE(2)) as an additional, but core, mediator of oogenesis in a human disease-vectoring mosquito, Aedes albopictus. Injection of aspirin (an inhibitor of cyclooxygenase (COX)) after blood-feeding (BF) inhibited oogenesis by preventing nurse cell dumping into a growing oocyte. The inhibitory effect was rescued by PGE(2) addition. PGE(2) was found to be rich in nurse cells and follicular epithelium after BF. RNA interference (RNAi) treatments of PG biosynthetic genes, including PLA(2) and two COX-like peroxidases, prevented egg development. Interestingly, 20E treatment significantly increased the expressions of PG biosynthetic genes, while the RNAi of Shade (which is a 20E biosynthetic gene) expression prevented inducible expressions after BF. Furthermore, RNAi treatments of PGE(2) receptor genes suppressed egg production, even under PGE(2). These results suggest that a signaling pathway of BF-20E-PGE(2) is required for early vitellogenesis in the mosquito.