Abstract: Pine wood nematode Bursaphelenchus xylophilus is a notorious invasive species from North America, which can kill a large amount of pine trees and causes economic losses and ecosystem destruction. There is a close relationship and ecological interaction between B. xylophilus and its companion microorganisms. This paper listed the species of companion microorganisms, reviewed their important ecological roles in the propagation and pathogenicity of the nematode, and discussed the pine wilt disease from the viewpoint of microecosystem. The companion fungi can supply food for B. xylophilus, hold the cycle of second infection of the nematode, increase the proportions of dauer juveniles, and benefit the infection and distribution of B. xylophilus. The companion bacteria can enhance the pathogenicity of B. xylophilus, promote the propagation of the nematode, benefit the pinene degradation, and thereby, promote the adaptability of the nematode.

Key words: pine wood nematode, companion fungi, companion bacteria, ecological interaction