The nematocidal activity and the structure-activity relationships of stilbenes.

The pinewood nematode, Bursaphelenchus xylophilus (Steiner et Buhrer) Nickle, is the causative agent of the pine wilt disease which has been devastating forests of Pinus densiflora Sieb.et Zucc. and P. thunbergii Parl. in Japan. To prevent the pine wilt disease, the development of nematocidal compound is required. Twenty-one synthesized stilbenes (1)-(20), (23), salicylic acid (21), and phenylsalicilate (22) were examined for their nematocidal activity against an isolate of B. xylophilus (T-4). Among the tested compounds, two fluorinated stilbenes (15) and (13), were found to be most potent compounds against T-4, demonstrating 99% and 98% lethality at 10 ppm concentration. The LD50 values of compounds 15 and 13 were 3 ppm, respectively.