Identification of the Core Region Responsible for the Activity of CmVg Promoter and Its Regulatory Transcription Factor BrC in Cnaphalocrocis Medinalis (lepidoptera: Pyralidae)

Insect reproduction depends critically on vitellogenesis, during which vitellogenin (Vg) is synthesized in the female fat body and incorporated into developing oocytes as an essential nutrient source. In this study, the promoter region of the vitellogenin gene (CmVg) of the rice leaf folder (Cnaphalocrocis medinalis) was predicted and cloned. A core active region was delineated within the CmVg promoter, and bioinformatic analysis revealed several predicted cis‑regulatory elements (CREs) for Broad‑Complex (BrC) transcription factors in the core region. Among four BrC protein candidates in the genome of C. medinalis, Cmed074000.1 significantly enhanced the transcriptional activity of CmVg. Disruption of the CRE of Cmed074000.1 strongly reduced the expression level of the reporter. Moreover, RNA interference-mediated knockdown of Cmed074000.1 in adult females significantly down‑regulated CmVg transcriptional levels and severely impaired egg production by 62.24%. This work provides the first evidence of a transcriptional pathway controlling CmVg expression in this pest, C. medinalis, offering novel insights into its reproductive biology and highlighting a potential target for future pest‑management strategies.