Phytochemistry and Nematicidal Activity of the Essential Oils from 8 Greek Lamiaceae Aromatic Plants and 13 Terpene Components

Eight essential oils (EOs) as well as 13 single terpenes were studied for their nematicidal activity against Meloidogyne incognita, for three immersion periods (24, 48, and 96 h). The EOs were isolated from eight Greek Lamiaceae species: Melissa officinalis, Sideritis clandestina, Origanum dictamnus, Ocimum basilicum, Mentha pule glum, Origanum vulgare, Vitex agnus castus, and Salvia officinalis. The EOs nematicidal activity was correlated to their chemical composition as well as to the pure terpenes' activity tested individually. Clear dose and time response relationships were established. The EOs of O. vulgare, O. dictamnus, M. pulegium, and M. officinalis exhibited high nematicidal activity against M. incognita, and the EC50 values (96 h) were calculated at 1.55, 1.72, 3.15, and 6.15 mu L/mL, respectively. The activity of the nematicidal terpenes was found to decrease in the order L-carvone, pulegone, trans-anethole, geraniol, eugenol, carvacrol, thymol, terpinen-4-ol, and the respective EC50 values (24 h) were calculated in the range of 115-392 mu g/mL. Terpenes tested individually were more active than as components in EO, implementing antagonistic action.