Electrophysiological responses and field attractants of Hoplia spectabilis Medvedev ( Coleoptera: Scarabaeidae ) adults to host plant volatiles

BACKGROUND: The Hoplia spectabilis (Coleoptera: Scarabaeidae) is a major pest threatening local shrubs in the plateau ecosystems of western China. However, little information is available on its chemical ecology. In this study, we aimed to identify host-plant volatiles used for host location by Hoplia spectabilis adults that are specialized to feed upon host plant foliage, and to further develop effective attractants for pest management. RESULTS: Field observations revealed that the beetles exhibited a strong feeding preference for Hippophae neurocarpa over Potentilla fruticosa and Myricaria germanica. Electroantennography (EAG) assays confirmed that both female and male beetles responded strongly to hexane extracts of host plant foliage. By using gas chromatography coupled with electroantennographic detection (GC-EAD) followed by GC-mass spectrometry, we identified 22 electrophysiologically active compounds, with (Z)-hex-3-en-1-ol and nonanal dominating the volatile profile of Hippophae neurocarpa (52.4%). A binary blend B of (Z)-hex-3-en-1-ol and nonanal was the most effective attractant, outperforming multi-component blend M consisting of the 11 EAD-active components shared by the three host plants. Volatilization kinetics demonstrated significantly higher release rates of (Z)-hex-3-en-1-ol and nonanal from blend B than from blend M, interpreting higher captures of beetles by blend B. CONCLUSION: These findings revealed that a binary blend of (Z)-hex-3-en-1-ol and nonanal is a highly effective attractant for Hoplia spectabilis with promising applications in monitoring, mass trapping and integrated pest management programmes. © 2026 Society of Chemical Industry.