Rapid diagnosis of the infection of pine tree with pine wood nematode (Bursaphelenchus xylophilus) by use of host-tree volatiles.

Attraction of the Bursaphelenchus xylophilus nematode toward 18 volatiles of Pinus species was evaluated by a Petri-dish bioassay under laboratory conditions to develop a rapid diagnostic kit. Among these compounds, α-pinene, β-pinene, and camphor showed significantly higher attractiveness to B. xylophilus in both the reproductive and dispersal stages, whereas these compounds were not active against Bursaphelenchus mucronatus . A trap tube was developed as a diagnostic kit, which consisted of a tube filled with 0.8% agar and a matrix impregnated with an attractant: α-pinene, β-pinene, or camphor. All tested compounds attracted a significantly higher number of B. xylophilus than that in the control treatment. No significant difference was observed among attractants. The cotton-ball matrix was significantly more effective than the filter-paper matrix for attracting B. xylophilus in the artificial pupal chamber bioassay. In a bioassay with pine wood nematode (PWN)-infected pine tree logs, B. xylophilus was initially attracted after an 8 h trap period and the number of B. xylophilus increased with time. The trap tube using camphor and the cotton-ball matrix were most effective for attracting B. xylophilus . The semiochemical-based tube-trapping method is simple to use, requires minimal labor, and is economical and effective for detecting B. xylophilus living in host pine trees during field sampling.