The oviduct serves as a delivery tube for mature eggs ovulated from ovaries to egg-laying sites. Oviduct secreted components play important roles in ovulation and fertilization in mammals, however, no oviduct secreted protein has been characterized in an insect to date. Here, we identified a gene highly expressed in the lateral oviduct of the adult females in the brown planthopper (BPH), Nilaparvata lugens, the most destructive rice insect pest. Western blotting and immunofluorescence analyses revealed that the gene encodes a protein that is specifically expressed in the lateral oviduct as a component of the gel-like material secreted by the oviduct epithelial cells into the lumen of the swollen part of the lateral oviducts. The protein was tentatively named N. lugens oviduct secreted protein (Nlodsp). RNA interference (RNAi) against NlOdsp transcripts caused a failure of the lateral oviducts to deliver oocytes to the common oviduct that was, by consequence, plugged by 1–2 oocytes. Moreover, although oocytes in the Nlodsp-deficient ovariole were not released to the oviduct, they continued to develop, finally resulting in the presence of several matured oocytes in an ovariole. These defects evidently declined female fecundity. Together, our results demonstrate that NlOdsp plays an essential role in egg transport through the oviduct during ovulation. This work deepens our understanding of insect reproductive system and provides a potential target gene for RNAi-based insect pest control.

输卵管作为从卵巢排卵到产卵部位的成熟卵子的输送管。输卵管分泌的成分在哺乳动物的排卵和受精中起重要作用，然而，迄今为止，尚未在昆虫中表征输卵管分泌的蛋白质。在这里，我们在褐飞虱（BPH）Nilaparvata lugens （最具破坏性的水稻害虫）的成年雌性的侧输卵管中鉴定了一个高度表达的基因。蛋白质印迹和免疫荧光分析表明，该基因编码一种蛋白质，该蛋白质在侧输卵管中特异性表达，作为输卵管上皮细胞分泌到侧输卵管肿胀部分的管腔中的凝胶样物质的组成部分。该蛋白质暂时命名为N. lugens输卵管分泌蛋白（Nlodsp）。针对NlOdsp转录物的RNA 干扰 (RNAi)导致侧向输卵管无法将卵母细胞输送到共同输卵管，结果被 1-2 个卵母细胞堵塞。此外，虽然 Nlodsp 缺陷的卵巢中的卵母细胞没有释放到输卵管，但它们继续发育，最终导致在一个卵巢中出现了几个成熟的卵母细胞。这些缺陷明显降低了女性的生育能力。总之，我们的结果表明 NlOdsp 在排卵期间通过输卵管的卵子运输中起着至关重要的作用。这项工作加深了我们对昆虫生殖系统的理解，并为基于 RNAi 的害虫控制提供了一个潜在的靶基因。