Recent Advances in Elucidating the Mechanism of Embryonic Diapause in Silkworm, Bombyx mori L.

Diapause in silkworm Bombyx mori L. is a complex adaptive strategy that ensures survival under adverse environmental conditions by temporarily halting embryonic development. Diapause hormone is a 24-amino acid neuropeptide secreted by suboesophageal ganglion of female pupae, which modulates trehalose metabolism, glycogen accumulation and oxygen consumption. Molecular mechanisms involved in calcineurin and protein kinase C (PKC) signaling, ROS-mediated stress responses and differential expression of ecdysteroid biosynthesis and signaling genes including Spo, Nvd, Shd, EcRA and E75. Key metabolic genes such as UGT, glucose dehydrogenase and mannosidase show stage-specific expression patterns between diapausing and non-diapausing eggs. The epigenetic regulation, PP1 and PP4 phosphatases and AMPK/ERK-MAPK pathways also play significant roles in embryonic arrest and reactivation. Artificial diapause termination techniques such as acid treatment, chilling and corona discharge impact gene expression patterns related to oxidative phosphorylation and chromatin remodeling. Integrating both physiological and molecular insights will enhance ability to manipulate diapause, offering promising applications for sericulture sustainability.