Abstract
Behavioral responses of Bursaphelenchus lignicolus to bitter and pungent substances were tested. The assay procedure was as follows. A pair of holes were perforated in agar plates in petri dishes. They were filled with agar containing a test chemical and untreated agar respectively. A pad of absorbent cotton impregnated with a suspension of the nematodes reared on the colonies of Botrytis cinerea was placed in the center of the agar plates. After incubation in darkness at 25°C for 3 days, the number of the nematodes in the treated and untreated agar disks were counted and analysed statistically. Among the nineteen substances tested, allyl isothiocyanate, naringenin, L-tyrosine, L-tryptophan and calcium chloride showed attractive effects; and, the first compound was most active. Capsaicin and magnesium chloride exhibited repellency, the former being highly active. The threshold values of activity for allyl isothiocyanate and capsaicin were comparable with that of 1-monoolein which was found at 1×10X-4M. Quinine hydrochloride, phenyl thiourea, caffein and diallyl disulfide exhibited moderate nematicidal activities.
