Feeding Preferences of Agrilus zanthoxylumi (Coleoptera: Buprestidae) in Relation to Host Plant Volatiles

The Chinese pepper buprestid beetle, <i>Agrilus zanthoxylumi</i> Li Meng Lou, 1989 (Coleoptera: Buprestidae), is a major trunk-boring pest affecting the yield and quality of <i>Zanthoxylum bungeanum</i>. Clarifying its feeding preferences among different pepper varieties and their associations with host-derived volatiles is important for understanding and improving effective management strategies. This study conducted feeding tests under no-choice and dual-choice conditions to evaluate the beetle's feeding preferences among three <i>Z. bungeanum</i> varieties-Fugu, Dahongpao, and Feng. Gas chromatography-mass spectrometry (GC-MS) was employed to analyze leaf volatiles, with factor analysis and partial least squares discriminant analysis (PLS-DA) used to identify key volatiles. Results showed that <i>A. zanthoxylumi</i> exhibited the highest resting frequency and feeding amount on <i>Z. bungeanum</i> Fugu leaves, with the lowest on <i>Z. bungeanum</i> Dahongpao leaves. Significant differences in unique volatiles were observed among the three varieties. <i>Z. bungeanum</i> Fugu contained 17 unique components, including (E)-4-hexen-1-ol, (-)-limonene, and (-)-α-pinene, with significantly higher quantities than <i>Z. bungeanum</i> Dahongpao and <i>bungeanum</i> Feng. Multivariate analyses further revealed distinct distributions in volatiles, with γ-terpinene, α-terpineol, and linalyl acetate emerging as key compounds distinguishing varieties. These results indicate that the feeding preferences of <i>A. zanthoxylumi</i> are closely related to host volatiles, suggesting variety-specific compounds may serve as primary chemical cues driving its preferences.