Nematicidal activity of monoterpenoids against the pine wood nematode (Bursaphelenchus xylophilus)

摘要

The nematicidal activity of twenty-six naturally occurring monoterpenoids was evaluated with a 96-microwell plate bioassay against the pine wood nematode, Bursaphelenchus xylophilus. Responses varied with test compounds and dose. Good nematicidal activity against male, female and juvenile nematodes of B. xylophilus was achieved with carvacrol, thymol, geraniol, nerol, (-)-meiithol, beta-citronellol, (+-)-citronellal and citral (mix. of cis and trans). Phenol, alcohol and aldehyde compounds were generally more toxic to B. xylophilus. Carvacrol and thymol showed the most potent nematicidal activity among test compounds. LC_(50) values of thymol and carvacrol against juvenile nematodes were 0.096 and 0.099 mg ml~(-1), respectively. Citral and citronellol showed similar toxicity to juvenile nematodes. Citronellal was more toxic to juvenile nematodes (LC_(50) = 0.253 mg ml~(-1)) than geraniol (LC_(50) -- 0.417 mg ml~(-1)). LC_(50) values of nerol and menthol against juvenile nematodes were 0.979 and 1.021 mg ml~ (-1), respectively. LC_(50) values of the other test compounds and trunk-injection nematicide, levamisole hydrochloride, were > 1.0 mg ml~(-1) within 4 hours after treatment.