miR-927 links nutrient signals and 20-hydroxyecdysone regulation and mediates oviposition in Bactrocera dorsalis

The interplay between lipid homeostasis and hormonal regulation is critical for reproductive success in female insects. The molecular mechanisms linking lipid metabolism to hormonal pathways, particularly ecdysteroid synthesis, remain poorly understood. In this study, we reveal a novel regulatory role of miR-927 in the oriental fruit fly, Bactrocera dorsalis. Using in vivo miRNA mimic/inhibitor assays, combined with an in vitro dual-luciferase reporter and RNA pull-down experiments, we demonstrated that miR-927 directly targets BdCYP315a1, a key enzyme in ecdysteroidogenesis, thereby repressing the 20-hydroxyecdysone (20E) levels. RNA interference of BdCYP315a1 confirmed its essential role in maintaining 20E homeostasis and proper developmental progression. Further, we show that miR-927 expression is regulated by the insulin/insulin-like signaling (IIS) pathway, linking nutritional status to hormonal control. Changes in miR-927, BdCYP315a1, and 20E levels corresponded with alterations in lipid content, ultimately influencing fecundity. These findings reveal a previously uncharacterized miRNA-mediated network integrating nutritional signals, hormonal regulation, and lipid metabolism to control reproductive outcomes. Our work provides novel insights into the molecular mechanisms underlying insect reproduction, highlights miRNAs as key mediators of hormone-lipid interactions, and offers valuable resources for identifying miRNA targets in non-model insect species.