Introduction

Abstract

Pine wilt disease results from a multitude of complicated, biological organisms, that is, the pathogen, a host and an insect vector and climatic conditions. The general disease cycle for pine wilt disease in the Asian temperate zone is as follows. In early summer, the vector of the disease, the Japanese pine sawyer, Monochamus alternatus, which harbors the dispersal fourth-stage (dauer) juveniles of the pathogenic pine wood nematode, Bursaphelenchus xylophilus (PWN) in its tracheal system, emerge from dead pine trees and feed (maturation feeding) on the twigs of healthy pine trees. PWNs invade the healthy host tree through the feeding wounds made at this time. They then feed on the host’s cells and multiply and eventually kill the host tree. After the death of the tree, the PWNs feed on fungi growing in the dead tree and maintain their population until the next year, while mature vectors lay eggs in recently killed trees, and the larvae which hatch from the eggs grow and become vectors the next year.