Pinewood nematode retention rate of its insect vector, Monochamus saltuarius adult emerged from Pinus koraiensis in pine wilt disease damaged stand in South Korea

Pinewood nematode, Bursaphelenchus xylophilus, the pathogen of pine wilt disease (PWD), can infect another healthy host only by its insect vectors, mainly the Monochamus beetles. To understand the relationship between B. xylophilus and Monochamus beetle is the key factor to clear up the pathology of PWD and to adapt proper control methods. In South Korea, we have applied single tree elimination method on PWD infected hosts in case of intermittent occurrence. We analyzed B. xylophilus retention rates and the number of B. xylophilus in its insect vector, Monochamus saltuarius emerged from dead logs damaged by PWD and dead branches of healthy host trees in Pinus koreaiensis stand. The average weight of M. saltuarius adult emerged from dead logs by PWD is heavier than that from dead branches of healthy host. The frequency of B. xylophilus retention of M. saltuarius in dead logs damaged by PWD was more than two times than dead branches of healthy host. B. xylophilus were mainly found in abdomen of M. saltuarius adult among its body parts. These results indicate that M. saltuarius adult with B. xolopohilus in its body emerged from uncontrolled dead branches of healthy host may infect the other healthy hosts as the potential spread source of PWD.