性信息素是昆虫两性个体间具有种特异性的化学语言，对于昆虫交配、繁衍及种间生殖隔离至关重要，研究昆虫近缘种间性信息素合成及调控的分化机制具有重要的科学意义和应用价值。甜菜夜蛾和斜纹夜蛾为同属姐妹种，其性信息素主组分分别为Z9,E12-14:OAc、Z9,E11-14:OAc，唯一不同的是第二个双键的位置。研究表明脱饱和酶基因负责昆虫性信息素成分中双键的合成，这两个姐妹种主要性息素双键位置的不同究竟是由于环境的选择导致脱饱和酶基因发生变异进而引起酶学特性的改变？还是因为相同脱饱和酶基因在不同昆虫中选择性表达的结果？本项目拟采用比较转录组学、真核表达、RNA干扰及酶活分析等方法进行综合研究，以期明确两个姐妹种性信息素腺体中脱饱和酶基因的差异及其在两者性信息素主组分分化中的作用。研究结果不仅有助于从分子水平解析姐妹种间性信息素的分化机制，也为设计和开发新型、高效的害虫行为调控技术提供科学指导。

Sex pheromone is a species-specific chemical language in insects, which can play an important role in mating, breeding, and reproductive isolation among species. Research that aims to elucidate the distinct mechanisms of sex pheromone component biosynthesis and regulation between closely related species of insects has important scientific significance and application value. Spodoptera exigua and S. litura are sibling moth species, and the major sex pheromone components in these species are Z9, E12-14:OAc and Z9, E11-14:OAc, respectively. The only difference in these components is the position of the second double bond. Some studies showed that the desaturase gene is responsible for the formation of double bonds during sex pheromone component biosynthesis. Whether the difference in enzymatic properties is due to the sequence variations of desaturase genes under the environmental selection? Or because the same desaturase genes selectively expressed in different insects? Using comparative transcriptomics, eukaryotic expression, RNA interference, enzyme activity assay and the other technologies, this study aimed to determine differences in the desaturase genes of S.exigua and S.litura, and the role of the desaturase gene in sex pheromone differentiation in these two sibling species. The findings might contribute to the elucidation of the mechanism of sex pheromone differentiation between sibling species, and also provide a scientific basis for the development of new and efficient pest behavior-control techniques.