Omics approaches in insect diapause research.

Diapause is a genetically programmed developmental or reproductive arrest that helps insects survive adverse seasonal conditions. Our understanding of the molecular regulation of this complex trait has significantly improved through the use of omics technologies over the last few decades. In this review, we have compiled current omics research on insect diapause, spanning transcriptomics, proteomics, metabolomics, lipidomics, epigenomics, genomics, and post-transcriptional regulatory approaches. Transcriptomics has led the field, showing that the diapause program develops gradually through a series of gene expression changes involving insulin/Forkhead box O (FOXO) signaling, circadian clock genes, and juvenile hormone and ecdysteroid pathways. Proteomic studies consistently show that mRNA and protein levels do not always match during diapause, emphasizing the importance of translational and post-translational regulation. Metabolomic and lipidomic analyses have identified a conserved set of metabolic adjustments, including lipid accumulation, membrane remodeling, and cryoprotectant production. Although still limited, epigenomic studies are beginning to provide functional evidence linking chromatin modifications to diapause regulation. Genomics is connecting diapause traits to candidate loci in the genome and to the evolutionary processes shaping diapause across populations. Across these layers, omics has reframed diapause from a program defined by a few candidate genes into a coordinated, large-scale molecular reprogramming, and has exposed regulatory layers, particularly post-transcriptional and translational control, that were largely inaccessible to earlier candidate-gene and physiological approaches. We emphasize the emerging benefits of integrating multiple omics approaches, which reveal regulatory mechanisms inaccessible via a single method. We argue that critical gaps include cell and tissue heterogeneity, limited functional validation, broader taxonomic representation, greater integration across omics layers, and stronger links between omics data and the evolutionary context of diapause. We also discuss how new omics technologies, such as single-cell sequencing, could enable novel insights into diapause regulation.