Relationship between pine wilt disease development in asymptomatic carrier trees of Bursaphelenchus xylophilus (Nematoda: Apelenchoididae) and their use by Monochamus alternatus (Coleoptera: Cerambycidae)

Abstract

To clarify the effect of asymptomatic carrier trees on the epidemic spread of pine wilt disease, we inoculated Bursaphelenchus xylophilus (Steiner and Buhrer) Nickle into ~10-year-old Pinus thunbergii Parl. trees to make asymptomatic carrier trees of the nematodes, and then we examined the relationship between pine wilt disease development in these trees and their use by Monochamus alternatus Hope. Mature adults of M. alternatus were attracted by and oviposited on trees that died in summer and fall, regardless of whether they died in the year of nematode infection or were asymptomatic during the infection year and died the next year. These results suggest that trees that die in summer and fall should be disposed of to help control M. alternatus and limit epidemic spread of the disease. In addition, we suggest the possibility that M. alternatus larvae may not grow and develop in trees that die after the infection year or that M. alternatus adults that emerge from such trees do not carry many B. xylophilus.