Chemotaxis of the pinewood nematode, Bursaphelenchus xylophilus, to volatiles associated with host pine, Pinus massoniana, and its vector Monochamus alternatus.

The pinewood nematode (PWN), Bursaphelenchus xylophilus, the most important invasive species in pine forests of Asia, is transported to new pine hosts by beetles of the genus Monochamus. Third-stage dispersal juveniles (J(III)) aggregate in pupal chambers around the vector as it matures. We demonstrated that the ratio of three terpenes (alpha-pinene, beta-pinene, and longifolene at 1:2.7:1.1) released by larval Monochamus alternatus strongly attract J(III), whereas the different ratio (1:0.1:0.01) of these three terpenes found in healthy xylem of Pinus massoniana attracts only the propagative stage (J(n)) of the nematode. We suggest that the volatiles produced by the host plants could be the basis of a chemoecological relationship between plant parasitic nematodes and their vector insects. Capture of J(III) with terpene-baited trap tubes deployed for 2 hr in the field was demonstrated. This technique may lead to the development of rapid sampling methodologies for use at either ports-of-entry or in the field.