Identification, Characterization, and Functional Analysis of Chitin Synthase Genes in Walker (Lepidoptera: Pyralidae).

Walker () causes significant damage to mulberry every year, and we currently lack effective and environmentally friendly ways to control the pest. Chitin synthase (CHS) is a critical regulatory enzyme related to chitin biosynthesis, which plays a vital role in the growth and development of insects. The function of CHS in , however, has not been studied. In this study, two chitin synthase genes ( and ) were screened from our previously created transcriptome database. The complete coding sequences of the two genes are 5,955 bp and 5,896 bp, respectively. Expression of and could be detected throughout all developmental stages. Relatively high expression levels of occurred in the head and integument and was most highly expressed in the midgut. Moreover, silencing of and using dsRNA reduced expression of downstream chitin metabolism pathway genes and resulted in abnormal development and wings stretching, but did not affect normal pupating of larvae. Furthermore, the inhibitor of chitin synthesis diflubenzuron (DFB) was used to further validate the RNAi result. DFB treatment significantly improved expression of , except , and their downstream genes, and also effected molting at 48 h (62% mortality rate) and 72 h (90% mortality rate), respectively. These results show that and play critical roles in the development and wing stretching in adults, indicating that the genes are attractive potential pest control targets.