Histone acetyltransferase p300/ <scp>CBP</scp> regulates reproductive diapause via the juvenile hormone pathway in the cabbage beetle, <i>Colaphellus bowringi</i>

Juvenile hormone (JH) serves as a pivotal endocrine regulator of reproductive diapause (also known as adult diapause) in insects, though the molecular mechanisms underlying JH signalling remain poorly characterised. In this study, we investigate the roles of the histone acetyltransferase p300/CBP in regulating reproductive diapause through JH signalling in the cabbage beetle Colaphellus bowringi. RNA interference-mediated knockdown of p300/CBP in reproductive females induced diapause-like phenotypes, including arrested ovarian maturation, suppressed vitellogenesis, increased lipid accumulation and upregulation of diapause-associated genes. These effects were accompanied by downregulation of key JH biosynthetic enzymes and signalling components. Although exogenous JH application decreased lipid accumulation, it failed to rescue ovarian development. Similar results were observed in diapause females following p300/CBP knockdown: JH analog treatment reduced lipid accumulations but did not restore ovarian development. Collectively, these findings demonstrate that p300/CBP regulates photoperiodic reproductive diapause by modulating both JH biosynthesis and signal transduction pathways in C. bowringi. Our results establish p300/CBP as a critical epigenetic mediator of JH-mediated reproductive diapause and provide new insights into the molecular mechanisms underlying environmental adaptation in insects.