Population Density and Host Preference of the Japanese Pine Sawyer () in the Qinling-Daba Mountains of China.

is a serious trunk-boring pest and is the most important and effective vector of the pine wood nematode , which causes pine wilt disease. The pine wilt disease poses a serious threat to forest vegetation and ecological security in the Qinling-Daba Mountains and their surrounding areas. In order to clarify whether the population density of larvae is related to the host preference of adults, we investigated the population density of overwintering larvae and explored the host preference of adults on , , and . The results show that the population density of larvae was significantly higher on than those on and . The development of larvae was continuous according to the measurements of the head capsule width and the pronotum width. Adults of preferred to oviposit on rather than on and . Our results indicate that the difference in the population density of larvae between different host plants was due to the oviposition preference of adults. In addition, the instars of larvae could not be accurately determined, because Dyar's law is not suitable for continuously developing individuals. This study could provide theoretical basis for the comprehensive prevention and control of the pine wilt disease in this region and adjacent areas.