The emerald ash borer (EAB, Agrilus planipennis), an ash-tree wood-boring beetle, has caused widespread mortality of ash. Asian ash, which coevolved with EAB, is considered more resistant than its North American and European congeners. Although some compounds and proteins related to resistance to EAB have been identified, the underlying ash resistance mechanism to EAB still needs further study. The Asian ash species, Fraxinus chinensis var. rhynchophylla, is highly resistant to EAB. In this study, metabolic and transcriptional profiling of the phloem of this species was investigated, and differentially expressed metabolites and genes were analyzed by comparing them with those of the susceptible F. pennsylvanica. Four hundred and twenty-eight metabolites were detected in both species, and several coumarins and lignans, which were exclusive to F. chinensis var. rhynchophylla, were identified. Compared with susceptible F. pennsylvanica, genes related to phenylpropanoid biosynthesis, ethylene (ET), and jasmonic acid (JA) biosynthesis and signaling in F. chinensis var. rhynchophylla were found to be up-regulated. It was hypothesized that coumarins, lignans, and ET and JA signaling might contribute to greater resistance to EAB in F. chinensis var. rhynchophylla. This study suggests candidate metabolites and genes for biomarker development in future ash-breeding programs.

Beta-cypermethrin is widely applied in Korean pine (Pinus koraiensis Siebold & Zucc.) seed orchards to control cone- and seed-infesting moths (e.g., Dioryctria spp.), yet its Wsublethal risks to non-target beneficial arthropods remain insufficiently characterized. Here, we systematically evaluated the ecological and physiological consequences of beta-cypermethrin exposure on the key parasitoid wasp Baryscapus dioryctriae Yang & Song, an important biological control agent in P. koraiensis forests. Adult wasps were exposed to LC₃₀ and LC₅₀ residue concentrations, and sublethal effects were quantified across reproductive, developmental, and biochemical endpoints over two generations. Sublethal exposure resulted in significant reductions in parasitism rates and offspring emergence, as well as altered developmental durations and adult longevity in both F₀ and F₁ generations. Enzymatic assays revealed time-dependent activation of detoxification enzymes (GST, CarE, AChE) alongside suppression of antioxidant defenses (CAT strongly; SOD early with partial recovery; POD biphasic), consistent with a sustained oxidative-stress burden. LC-MS/MS residue analysis further confirmed the accumulation and slow clearance of both beta-cypermethrin and its metabolite 3-phenoxybenzoic acid (PBA) within parasitoid tissues. These findings collectively demonstrate that even non-lethal concentrations of beta-cypermethrin can undermine the ecological fitness and persistence of B. dioryctriae, posing a tangible threat to the sustainability of biological control services. To safeguard beneficial parasitoids, integrated pest management strategies must incorporate selective insecticide use and exposure mitigation, especially in forest habitats where biological control is indispensable.