Functional proteomic insights into the lateral oviduct-associated secretions of a bean bug.

The secretions within the lateral oviduct lumen of the insect female reproductive tract (FRT) play crucial roles in reproduction, yet their protein composition and functional mechanisms remain poorly understood. In this study, we revealed that the lateral oviduct of the bean bug, Riptortus pedestris, is composed of an outer muscle layer and an inner epithelium with a microvillar border. Proteomic analysis identified 159 FRT-highly expressed proteins, with functional characterization focusing on 10 putative secretory proteins, including 2 ovary-specific (RpLoap2 and RpLoap4), 7 oviduct-specific (RpLoap3 and RpLoap5-10), and 1 ovary-highly expressed (RpLoap1) genes. Notably, RNAi-mediated knockdown of RpLoap2 severely impaired choriogenesis, resulting in complete reproductive failure. These findings provide valuable insights into insect reproduction biology from the perspective of lateral oviduct-associated secretions and establish RpLoap2 as essential for successful reproduction in R. pedestris.