Pine wild disease (PWD) is caused by pine wood nematode, Bursaphelenchus xylophilus and insect vector, Monochamus alternatus. Since its first incidence in Japan in early 20th century, several control strategies (e.g. cleaning sawyer, selective planting of resistant trees) have been conducted, but the annual loss of pines by PWD still reaches half a million (Togashi and Shigesada 2006*). To make a projection of epidemic dynamics of PWD and to propose an effective control, we construct host-parasite-vector model with genetic variability in nematode virulence.

We first study the effect of introduction of resistant trees. We found that the higher the resistance and the frequency of resistant trees, the more virulent does the nematode population become. The amount of dead trees at equilibrium can nonetheless be reduced by introducing resistance. We also analyzed the system of M. saltuarius, which is thought to be responsible for the spread of PWD in northern Japan.

*Pop. Eco. 48: 271-283