The microRNA pathway regulates obligatory aestivation in the cabbage stem flea beetle Psylliodes chrysocephala.

Aestivation, or summer diapause, is a dormancy strategy that enables animals to survive hot and dry summer conditions. Despite its ecological importance, the gene regulatory mechanisms underlying aestivation remain poorly understood. MicroRNAs (miRNAs) are post-transcriptional regulators involved in various biological processes, including development. Here, we investigated the role of miRNAs in obligatory aestivation in the cabbage stem flea beetle (Psylliodes chrysocephala), a major pest of oilseed rape. Small RNA sequencing revealed that approximately 25% of miRNAs were differentially abundant during aestivation. RNA interference-mediated inhibition of the miRNA pathway, combined with proteomics, identified 116 miRNA-regulated proteins involved in metabolic and catabolic processes. Integrated transcriptome analysis suggested that 71% of these miRNA-regulated proteins were also downregulated at the mRNA level, while the remaining 29% were likely regulated primarily through translational inhibition. Degradome sequencing confirmed miRNA-mediated regulation of several transcripts and suggested exonucleolytic decay as the predominant mechanism. Disruption of the miRNA pathway impaired key aestivation traits, including metabolic suppression, changes in body composition, behavior inhibition, and heat tolerance. These findings suggest a central role for miRNAs in regulating insect dormancy, with implications for understanding climate change impacts on insect physiology and for developing novel pest control strategies.