UDP-glycosyltransferases-mediated vitellogenin protein biogenesis reveals juvenile hormone I-specific dominance in Spodoptera frugiperda reproductive programming.

Juvenile hormone (JH) critically regulates reproduction in Spodoptera frugiperda (FAW) via its signaling cascade. We dissected isoform-specific roles of JH I, II, and III by using hormone injection, RNAi, and RNA-seq. Systematic modulation of JH variants revealed distinct roles in ovarian development, egg production, and vitellogenin (Vg) dynamics. Transcriptomic profiling identified JH I as the most potent inducer of reproductive pathways, specifically enriching the steroid hormone biosynthesis pathway. Within this pathway, two UDP-glycosyltransferases (UGT), SfUGT2 and SfUGT2-like, were identified as key regulators of Vg synthesis through RNAi knockdown and functional validation (qPCR, Western blot). Silencing either gene reduced Vg levels and impaired ovarian maturation. JH I exhibited the strongest induction of SfUGT2/SfUGT2-like expression, correlating with its superior reproductive activation. Notably, JH III synergistically amplified JH I/II-induced Vg accumulation and egg production, as evidenced by co-treatment assays. This cooperative interplay highlights a tiered regulatory network among JH isoforms, and provide novel insights into the endocrine regulation of reproduction in FAW, also highlight the potential for targeted manipulation of JH signaling for pest control strategies.