Flight and Walking Performance of Dark Black Chafer Beetle Holotrichia parallela (Coleoptera: Scarabaeidae) in the Presence of Known Hosts and Attractive Nonhost Plants

Holotrichia parallela damages seriously on peanut (Arachis hypogaea) pods. Elucidation of its flight and walking performance in the presence of different plants may provide an insight in its host selection process and an explanation to its strong olfactory preference to an attractive nonhost, castor bean (Ricinus communis). We determined the relationships among flight performance, mate choice, and body weight of H. parallela beetles, and then investigated their flight and walking patterns in the presence of known hosts and attractive nonhost plants using a flight mill and a locomotion compensator, respectively. Body weights were not related to mating success, regardless of sex. The flight proportion of selected females drastically decreased compared with nonselected females, nonselected males, and selected males. Within mated males, heavier individuals exhibited poorer flight performance than lighter ones. In flight bioassay, peanut showed an arrestment effect on virgin females. For walking activity factors (distance, time, and speed), the host plants velvetleaf (Abutilon theophrasti) and Siberian elm (Ulmus pumila) elicited the strongest responses in females and males, respectively. Interestingly, the most preferred adult host, Siberian elm, and the nonhost, castor bean, elicited the highest values of two orientation factors (orientation and upwind length) in females. The chemical similarity hypothesis, which states that feeding or oviposition of insects mistakenly on nonhost can be traced to their chemical similarity to actual hosts, could explain the attraction of H. parallela to castor bean.