食性分化表现为食物的选择性，是昆虫高效利用食物资源的进化适应，也是同域新种形成的重要途径。在全变态昆虫中，食物的选择性主要取决于雌成虫向不同寄主产卵的选择性，其中嗅觉起主导作用，夜行性蛾类尤其如此。研究近缘种食性分化的嗅觉机制，对于探讨新种形成、嗅觉演化及害虫行为控制均具重要意义。本项目拟以寄主植物明显不同的二化螟和芦苞螟一对姐妹种为系统，针对雌成虫的嗅觉适应，在前期已有工作的基础上，首先通过化学分析、行为测定等技术，对两种螟虫的各自寄主植物水稻和芦苇的活性气味组分进行分离和鉴定，明确导致两个姐妹种选择不同寄主植物产卵的关键趋、避气味组分；然后利用基因克隆、体外表达及功能研究等技术，明确昆虫感受上述关键植物气味组分的嗅觉基因，并比较它们在序列和表达等方面在两种螟虫间的差异，探讨两个姐妹种趋向不同寄主植物产卵的分子机制。研究成果可望为相关理论及在害虫控制方面的应用提供重要依据和指导。

Feeding differentiation is an evolutionary adaptation for high efficiency in use of food resources, and a main means of sympatric speciation. In moths, food preference is highly determined by the ovipositional preference of female adults, and the later mainly by olfaction. Therefore, it is important to explore the olfactory mechanisms of feeding differentiation among sibling species, for better understanding of sympatric speciation, olfactory evolution and behavioral strategy for pest control. Our project aims to explore the olfactory mechanisms underlying the feeding differentiation between two sibling species of Chilo supperssalis and C. luteellus at two aspects: 1) Identification the two host plant odors and measurement of theie activity of atractiveness for two moths by using EAG, olfactometer and cage bioassay methods. 2) Determination of the olfactory genes associated with the feeding differentiation by in vitro and in vivo method.Based on above studies, the olfactory mechanisms of ovipositional differentiation in host plants between the two moth species could be elucidated, and some behaviorally active plant odors could be determined for potential use in the pest control.