Blue-stain fungi were mainly isolated from the wood of pine wilt-killed Pinus densiflora. Intense blue-stain on the pupal chamber walls of the Japanese pine sawyer (Monochamus alternatus) increased the number of pinewood nematodes (Bursaphelenchus xylophilus) aggregating around such chambers and the number carried by the beetles that emerged from the chambers. There were differences in the numbers of nematodes carried by beetles among individual trees from which the beetles emerged. The beetles emerging from dry chambers carried relatively few nematodes.
Although fourth-stage dispersal juveniles (JIV) of Bursaphelenchus xylophilus, the pinewood nematode (PWN), developed in the presence of both Monochamus alternatus and Psacothea hilaris, the numbers and the percentage of JIV were far higher in the presence of the former than of the latter. JIV first appeared 7 days after pupation of M. alternatus and the number increased from the day of beetle eclosion to the third day thereafter, then remained stable. We conclude that the presence of specific vectors affects both the life history of the PWN and the numbers of nematodes carried by vectors emerging from killed pine trees.