LAUSR

Laboratory experiments were conducted to investigate the possible nematicidal effect of the four terpenes, carvacrol, geraniol, eugenol and thymol, against the stem and bulb nematode Ditylenchus dipsaci (Kuhn, 1857) Filipjev, Proceedings of the Helminthological Society of Washington, 3, 80–82, 1936, isolated from infested garlic cloves. In in vitro tests the observed nematicidal activity of terpenes in descending order was carvacrol > eugenol > geraniol > thymol. Carvacrol exhibited the highest activity of 100% mortality when it was tested at the concentration of 2000 μl/L. No synergistic action was recorded when all four terpenes were used in mixture. In soil experiments thymol showed the highest nematicidal activity amongst all the other terpenes followed by carvacrol. Our results indicate that there is a positive correlation between the concentration and the exposure time. In addition, increasing the dose of each terpene increased paralysis rates of the nematode were recorded. These results strongly show the nematicidal activity of terpenes, but further studies are needed to ascertain their mode of action against nematodes.