Seasonal variations in the incidence of Monochamus alternatus adults (Coleoptera: Cerambycidae) and other major Coleoptera: a two-year monitor in the pine forests of Hangzhou, Eastern China

Abstract

The Japanese pine sawyer, Monochamus alternatus Hope (Coleoptera: Cerambycidae), is the key factor in the subsequent Bursaphelenchus xylophilus distribution and dispersal from wilt-killed to healthy pines during maturation feeding and oviposition. Therefore, effective monitoring of M. alternatus populations is needed for the surveillance of pinewood nematode disease in infected or noninfected areas. The results presented here involved the seasonal variations of M. alternatus adults and other major Coleoptera in pine forests from 2011 to 2012 in the Xiaoshan District, which is surrounded by B. xylophilus-infected areas, in Zhejiang Province, Eastern China. M. alternatus adults occurred at one generation per year, and the active period for adults lasts from middle-May to early-September, with peak numbers recorded in late-June. The data indicated that the population density of M. alternatus in the investigated forests is very low. However, bark beetles and pine weevils at a high-density level, were active and emerged earlier than M. alternatus. We suggest that a high alert level must be maintained regarding the damage of bark beetles or pine weevils, which might lead to the facilitation of B. xylophilus invasion process.