Screening and Expression Characteristics of Trehalose Transporter Genes in the Parasitic Wasp Baryscapus dioryctriae (Hymenoptera: Eulophidae)

Trehalose serves as both a hemolymph sugar and stress protectant, playing pivotal roles in insect energy metabolism, development, and stress adaptation. Its transmembrane transport is mediated by trehalose transporters (TRETs). Baryscapus dioryctriae, a parasitoid wasp targeting the red pine shoot borer, shows great potential for biocontrol. Prior genomic assemblies indicated prominent expansion of the Tret gene family in this wasp, yet systematic characterization of these genes has not been reported. Here, leveraging a chromosome-level genome, we identified 94 BdioTrets. Phylogenetic analysis placed them closest to Phytomastichus coffea Trets (maximum identity: 88.15%). Most members conserved the GRR/K motif, N-glycosylation sites, and key residues in TM7/TM10. Fourteen candidate genes were further verified via reverse transcription quantitative PCR (RT-qPCR), and Pearson correlation analysis showed that 11 of the 14 candidate genes have strong and significant positive correlations for their tissue expression profiles (r > 0.7, p < 0.05), indicating consistent expression trends between RNA-seq and RT-qPCR. These genes exhibited stage-specific expression: BdioTret9 peaked in eggs; BdioTret3,5 and 67 in larvae; BdioTret25 in prepupae; and BdioTret6 in pupae, while eight others dominated in adults. Tissue-specific profiling revealed pronounced sexual dimorphism in antennal expression and distinct localization in the abdomen (sex-biased) and legs. Our findings demonstrate that the large-scale BdioTrets expansion, coupled with precise spatiotemporal regulation, establishes a flexible energy network supporting the parasitic lifecycle. These results lay a fundamental framework for future functional investigations of TRETs in hymenopteran parasitoids.