Olfactory and visual responses of the long-legged chafer Hoplia spectabilis Medvedev (Coleoptera: Scarabaeidae) in Qinghai province, China

The long-legged chafer, Hoplia spectabilis Medvedev, has recently been recorded in outbreak numbers in pastureland of Qinghai province, China. Field trapping experiments, using cross-pane funnel traps, showed that H. spectabilis adults were not significantly attracted to host plant branches (Dasiphora fructicosa). However, they were slightly attracted to similar host plant branches infested by conspecific beetles, possibly due to weakly attractive volatiles, such as (Z)-3-hexenyl acetate, released from the beetle-damaged host leaves. That compound was weakly attractive when released from traps. However, H. spectabilis beetles showed strong visual responses to trap panes painted yellow or white, with weaker responses to blue and red or green, and the least to black panes. Black cross-pane funnel traps intercepted significantly more beetles at 0.2-1.5 m above ground than did the traps at 2.5 m. The mean flight height based on trap catches was 0.88 „b 0.76 yielding an effective flight layer of 1.9 m. Flight response of the beetles to different colored barrier traps occurred between 10:00 and 18:00, and peaked between 12:00-14:00 when daily temperatures reached their maximum. Unbaited yellow or white cross-pane funnel (barrier) traps are recommended for both monitoring and mass-trapping operational programs against this economically and ecologically important scarab beetle.