The rice leaf folder (RLF), Cnaphalocrocis medinalis, is one of the major pests of rice, and chitin synthase is a key enzyme for the chitin synthesis pathway in insects. In this study, the chitin synthase B gene from C. medinalis (CmCHSB) was cloned and characterized. The cDNA of CmCHSB is 4824 bp in length, containing an open reading frame of 4578 nucleotides that encodes 1525 amino acids. The CmCHSB zymoprotein consists of 10 transmembrane domains (TMDs) in the N-terminus, a middle conserved catalytic domain, and 7 TMDs in the C-terminus. Homology and phylogenetic analyses revealed that CmCHSB possesses the closest relationship with its homolog in Ostrinia furnacalis. CmCHSB was expressed throughout development and in all of the adult tissues tested, with the highest expression level in the adult and in the midgut. Silencing of CmCHSB through RNA interference (RNAi) severely affected RLF larval growth and caused larval lethality. Our results revealed that CmCHSB is essential for RLF growth and development, which sheds new light on the characteristics and functions of this gene. These findings will be helpful for green control of RLF, by targeting the CmCHSB gene using RNAi technology.

稻纵卷叶RL（Cnaphalocrocis medinalis）是水稻的主要害虫之一，几丁质合酶是昆虫几丁质合成途径的关键酶。在这项研究中，从C. medinalis（CmCHSB）的几丁质合酶B基因被克隆和鉴定。CmCHSB的cDNA长度为4824 bp，包含一个4578个核苷酸的开放阅读框，编码1525个氨基酸。CmCHSB酶蛋白由N端的10个跨膜结构域（TMD），中间保守的催化结构域和C端的7个TMD组成。同源性和系统发育分析表明，CmCHSB拥有其在同源关系最密切的亚洲玉米螟。CmCHSB在整个发育过程中以及在所有测试的成人组织中都表达，在成人和中肠中的表达水平最高。通过RNA干扰（RNAi）沉默CmCHSB会严重影响RLF幼虫的生长并导致幼虫致死率。我们的结果表明，CmCHSB对于RLF的生长和发育至关重要，这为该基因的特征和功能提供了新的思路。这些发现将有助于通过使用RNAi技术靶向CmCHSB基因来对RLF进行绿色控制。