Disruption of Energy Metabolism, Locomotion, and Stress Tolerance by BxPDHB Silencing in Bursaphelenchus xylophilus: Implications for RNAi-Based Control of Pine Wilt Disease

Bursaphelenchus xylophilus combines strong locomotory capacity with high stress tolerance, and the coordinated action of these two traits underpins its global invasion and dispersal. Yet the molecular mechanisms coupling locomotion to stress tolerance remain poorly understood. Here, we focused on the JIII dispersal-stage juveniles, a life-history stage that simultaneously demands high locomotory output and robust stress resistance. Using weighted gene co-expression network analysis (WGCNA), gene set enrichment analysis (GSEA), and random forest machine learning, we systematically screened for hub genes that may jointly regulate locomotion and stress tolerance, and then functionally validated the candidate target by RNA interference (RNAi). The gene encoding the β subunit of the pyruvate dehydrogenase complex (PDHB) was identified as the core candidate target, positioned at the metabolic hub linking glycolysis to the tricarboxylic acid (TCA) cycle. Silencing of BxPDHB significantly increased pyruvate content (~4.61-fold), markedly reduced ATP levels (~16.30% decrease), drastically decreased head-swing frequency (~50.00% reduction), significantly elevated reactive oxygen species (ROS) levels (~4.26-fold), and decreased survival rate (~26.02% reduction), producing a cascade of substrate accumulation, energy deficiency, impaired locomotion, and exacerbated oxidative stress. These results suggest that PDHB, through its role in the energy output of aerobic respiration, may influence locomotory behavior and antioxidant defense, consistent with a key node linking energy metabolism, locomotion, and oxidative stress. This study highlights the potential hub role of a core energy-metabolism enzyme in the coordinated regulation of locomotion and stress tolerance in B. xylophilus, providing new molecular evidence for understanding its dispersal adaptability. Moreover, as a node that maintains basal energy metabolism across multiple active life stages, PDHB represents a promising candidate molecular target for the development of RNA-based biopesticides delivered via trunk injection or nanocarrier-mediated approaches, with potential application value for the green control of pine wilt disease.