Exploring the Olfactory Recognition of Elaeagnus angustifolia Volatiles in Anoplophora glabripennis Through Antennal Transcriptome Analysis and Molecular Characterization of Classic OBPs

Anoplophora glabripennis is a destructive forest pest. Elaeagnus angustifolia attracts A. glabripennis for feeding and oviposition, but its gum encapsulates and kills the eggs, functioning as a dead-end trap tree. However, the olfactory mechanisms by which A. glabripennis recognizes E. angustifolia volatiles remain unclear. In this study, we analyzed the antennal transcriptome of female adult A. glabripennis exposed to E. angustifolia volatiles. Ten OBP genes were significantly up-regulated in response to the volatiles, including six Classic OBPs and four Minus-C OBPs (log2 fold changes: 1.02–3.01). qRT-PCR showed AglaOBP1/2/3 were highly and specifically expressed in the antennae, suggesting key olfactory roles. Static molecular docking showed that all three OBPs bound 22 E. angustifolia volatiles, each displaying the highest affinity for (+)-Longifolene, with AglaOBP1 exhibiting the strongest binding. Nevertheless, 200 ns MD simulations revealed a shift: the AglaOBP3–(+)-Longifolene complex displayed the greatest structural stability, not AglaOBP1. MM/PBSA corrected the initial docking screen and confirmed that AglaOBP3 had the strongest thermodynamic binding affinity for (+)-Longifolene (ΔGbind = −30.94 ± 2.57 kcal·mol−1). This study provides novel molecular insights into the olfactory recognition of E. angustifolia volatiles in A. glabripennis, laying a foundation for future functional validation and sustainable pest management.