2021 Volume 103 Issue 5 Pages 367-371
In this study, we aimed to evaluate the risk of pine wilt disease (PWD) caused by the pinewood nematode (PWN) due to the trimming of pine twigs. For this, we determined if the pine twig trimming attracts the adults of the Japanese pine sawyer (Monochamus alternatus), a potential vector of this disease. Twelve healthy pine (Pinus densiflora) trees (six each in the treatment and control group) were selected as test trees. Twigs of the six individuals in the treatment group were intensively trimmed in mid-July 2020. Feeding wounds and oviposition scars created by M. alternatus following trimming were compared between the treatment and control groups. The number of feeding wounds did not significantly differ between the two groups (mean, 4.7 and 4.0 per tree). However, oviposition scars were observed only in the treatment group (mean, 1.8 per tree), indicating a significant treatment effect. Conclusively, the pine twig trimming attracts the mature females of M. alternatus for oviposition, thereby increasing the possibility of PWN transmission into the pine trees. Accordingly, to reduce the risk of PWDPWN, twig trimming should be avoided during the season when females carry many nematodes.
