One thing leads to another – Significant changes in microRNAs abundances suggest they have a role regulating the transition from diapause to post-diapause quiescence in overwintering Megachile rotundata

In spite of recent efforts to understand how insect diapause is regulated, the molecular regulation of the transition between diapause and post-diapause quiescence (i.e. diapause termination), remains a conspicuous knowledge gap. This study used high-throughput sequencing and differential expression analysis to evaluate differences in the abundances of microRNAs in diapausing and post-diapausing quiescent prepupae of Megachile rotundata, a highly managed pollinator of alfalfa. MicroRNAs are small, noncoding RNAs that regulate gene expression by inhibiting the translation of their gene targets. Twenty-three conserved and novel microRNAs were differentially regulated in diapausing prepupae, sampled in November, compared to quiescent post-diapause prepupae, sampled in May. Functional annotation of the predicted targets of these microRNAs suggests their function is to regulate diapause-relevant functions such as intracellular signal transduction (e.g. Wnt, MAPK, FOXO, and Hippo signaling), DNA transcription, and longevity. With the exception of miR-71-3p, all differentially regulated microRNAs were more abundant (i.e. upregulated) in post-diapause prepupae than in their diapausing counterparts. Since microRNAs inhibit translation, these data suggest microRNAs may have a role in the “escape” from diapause by limiting the synthesis of proteins that had been preventing continued development and/or metabolism during diapause.