Metamorphosis in insects is regulated by hormonal signals and metabolic pathways. In this study, we characterized a 20E-mediated miR-2788/Treh1 regulatory axis involved in the larval-to-pupal transition in the leaf beetle Galeruca daurica. Dual-luciferase assays and expression profiling suggest that miR-2788 directly targets and suppresses trehalase 1 (Treh1), a key enzyme for trehalose hydrolysis. We found that exogenous 20E treatment significantly downregulated miR-2788, leading to the derepression of Treh1 and increased expression of chitin biosynthetic genes (CHI, CHS, and GPI). Conversely, miR-2788 overexpression or Treh1 silencing via RNAi resulted in massive trehalose accumulation, reduced chitin synthesis, and lethal developmental arrest during the metamorphic transition. Furthermore, pharmacological inhibition of Treh1 with Validamycin not only recapitulated these chitin-deficiency phenotypes but was also associated with an upregulation of miR-2788. These results describe a signaling cascade where 20E modulates the conversion of carbohydrate to chitin through the miR-2788/Treh1 axis. This study advances our understanding of hormonal–miRNA–metabolic crosstalk and identifies miR-2788 as a potential target for RNAi-based biopesticide development.

Lipophorin receptors play a crucial role in the reproductive development of insects. However, their regulatory function in insect reproductive diapause remains poorly understood. In this study, a lipophorin receptor gene (GdLpR) was cloned from Galeruca daurica using RT-PCR. The open reading frame (ORF) of GdLpR is 2589 bp in length, encoding 862 amino acids, and possesses typical structural characteristics of the lipophorin receptor family. RT-qPCR analysis indicated that the expression of GdLpR is up-regulated in G. daurica adults before diapause, exhibits an expression pattern of initial down-regulation, subsequent up-regulation, and then further down-regulation during diapause, and is up-regulated again after diapause termination. After RNA interference of GdLpR, the expression levels of diapause-related genes ecdysone receptor (EcR), nuclear hormone receptor (HR3), and vitellogenin (Vg) were downregulated, while the expression level of fatty acid synthase (FAS) and total lipid content were upregulated, leading to premature diapause in adult G. daurica. These results indicate that GdLpR is involved in the regulation of reproductive diapause in G. daurica.

The Asian migratory locust (Oedaleus decorus asiaticus) is a major grassland pest in northern China, with outbreak dynamics closely linked to phase transition mediated by chemical communication. This study focused on a chemosensory protein, OasiCSP12, to explore its potential role in this process. We analyzed its expression patterns via qRT-PCR, purified the recombinant protein, and identified potential ligands through fluorescence competitive binding assays. Structural insights were gained through homology modeling, molecular docking, and molecular dynamics simulations, with binding energetics assessed using MM/PBSA. Results showed that OasiCSP12 expression is phase- and sex-specific, being significantly upregulated in gregarious adult antennae. The protein bound selectively to 15 locust body-surface volatiles, including aldehydes and esters. Its structure features a hydrophobic binding cavity where van der Waals interactions, primarily predicted to be mediated by residues Val86, Leu71, and Trp101, likely stabilize ligand complexes. These findings indicate that OasiCSP12 is potentially associated with both chemical perception and phase regulation in O. d. asiaticus, providing a candidate target for developing behavior-based green control strategies against this pest.