Transcriptomic Characterization of miRNAs in Fairmaire in Response to 20-Hydroxyecdysone Treatment.

Background/objectives: , a major pest of elm trees, causes extensive ecological and economic damage through rapid population growth and defoliation. Existing research mainly focuses on its biological traits and chemical control, with little knowledge about its reproductive development mechanisms, a key factor in population expansion. In other insects, the steroid hormone 20-hydroxyecdysone (20E) regulates development and reproduction via microRNA (miRNA)-mediated pathways, but this has not been studied in . This study aimed to systematically identify miRNAs responsive to 20E in and unravel their roles in regulating reproduction and metabolic pathways, providing foundational insights into hormone-miRNA crosstalk in this ecologically significant pest.

Methods: Adult beetles (collected from Baotou, Inner Mongolia) were injected with 1.0 μg/μL 20E or control. Total RNA from three biological replicates (10 adults each) was sequenced, followed by miRNA identification, differential expression analysis, target prediction, and functional enrichment.

Results: Small RNA sequencing identified 205 miRNAs (162 conserved, 43 novel), with 12 DEMs post-20E treatment. Target prediction linked these miRNAs to 7270 genes, including key regulators of the signaling pathway and MAPK signaling pathway. KEGG analysis highlighted lipid metabolism and stress response pathways.

Conclusions: This study revealed that 20E modulates miRNA networks to regulate and MAPK pathways in , suggesting hormonal control of lipid metabolism and developmental processes. As the first miRNA resource for this pest, our findings provide mechanistic insights into 20E-miRNA crosstalk and identify potential molecular targets for disrupting its reproductive biology, laying a foundation for eco-friendly pest control.