Factors Affecting the Number of Bursaphelenchus xylophilus (Nematoda: Aphelenchoididae) Carried by Newly Emerged Adults of Monochamus alternatus (Coleoptera: Cerambycidae)

Abstract

Using ca. 1 m long logs of Pinus thunbergii, an experiment and an examination were conducted to elucidate the effects of Bursaphelenchus xylophilus density and water content in xylem on B. xylophilus abundance carried by Monochamus alternatus adults at emergence. The nematode density in xylem was determined in November and December. The water content was determined in August after the end of bettle emergence. Both factors were shown significantly to affect the nematode abundance within beetles. Beetles carried less than 30 nematodes at the nematode densities of less than 10 per gram dry xylem while some beetles carried more than 100, 000 nematodes at nematode densities of more than 100 per gram, resulting in a large variation in the number of nematodes carried by beetles. The frequency distribution of nematode abundance within beetles was not significantly affected by the part of the tree from which beetles emerged, i.e. trunks of branches, not by the time of host tree decline. © 1989, JAPANESE SOCIETY OF APPLIED ENTOMOLOGY AND ZOOLOGY. All rights reserved.