Dispersal capacity of Monochamus saltuarius on flight mills

Abstract

Pine wilt disease (PWD) is caused by pine wood nematode (PWN), Bursaphelenchus xylophilus (Steiner & Buhrer) Nickle, transmitted by Monochamus saltuarius (Gebler) (Coleoptera: Cerambycidae) to healthy Korean white pine, Pinus koraiensis Siebold & Zucc. (Pinaceae). It is a serious threat to forest ecosystems worldwide. To better understand and predict the spread of PWD in Korean white pine forests, we investigated flight distance, time, and velocity of M. saltuarius adults using computer-linked flight mills under laboratory conditions. In addition, we investigated the impact of biological characteristics on flight distance of this vector insect. Flight distance and time were individually measured during flight mill experiments (30 min per session) and repeatedly measured twice a week. Our results revealed large variation in flight distance within the population. Half of the beetles tested in this study flew more than 1 km and no difference was found between males and females when only fliers were considered. The average flight velocity of females was higher than that of males, but intermittent flights were observed more frequently in males compared to females. Both unmated male and female M. saltuarius adults can fly more than 5 km during their entire lifespan based on these flight mill experiments. Consequently, guidelines for managing dead pines in infected areas should consider a large buffer zone around PWN-invaded areas so that uninfected areas are beyond the dispersal capacity of M. saltuarius.