Abstract:  Diapause is a strategy for insect to avoid harsh environment, and has a great significance for continuation of insect population. In particular, facultative diapause can be affected by periodic seasonal changes, in which epigenetics may play critical roles. Epigenetics refers to heritable variations independent of DNA sequence, including various modifications at DNA, RNA, protein and chromatin levels, and may be involved in development plasticity. The research of epigenetic regulation of insect diapause mainly focuses on two aspects: one is how epigenetic regulation respond to environmental signals, and the other is how environmental signal induces epigenetic regulation in insect diapause. Although it has been reported that DNA methylation can respond to photoperiodic signal and histone acetylation can be coupled with endocrine systems, the detail mechanisms of epigenetic regulations of insect diapause, however, are not completely revealed. Regulations of diapause induced by epigenetics have been reported in multiple types of insect diapause. For the same diapause process, there may be co-regulation between different epigenetic mechanisms. However, how this synergy responds to environmental signals and how it precisely regulates insect diapause are still unknown. In conclusion, the previous research only indicated the possibility of epigenetic regulation in insect diapause, but the molecular mechanisms are scarcely known and need further study. Especially the following aspects might be critical in the future research: the molecular mechanism of epigenetics responding to diapause-induced environmental signals, the molecular mechanism of epigenetics coupled with endocrine regulation, the cell signal transduction of epigenetic regulation, and the synergetic regulation of epigenetics in insect diapause.

Key words: Insects, diapause, epigenetic regulation, DNA methylation, post-translation modification, small non-coding RNA