EVALUATION OF NEMATICIDAL EFFECTS OF MONOTERPENES AGAINST ROOT-KNOT NEMATODE, Meloidogyne incognita

Abstract

Nematicidal activity of 12 monoterpenes namely, camphene, (R)-camphor, (R)-carvone, 1-8-cineole, cuminaldehyde, (S)-fenchone, geraniol, (S)-limonene, (R)-linalool, (1R,2S,5R)-menthol, citral and thymol was evaluated against root-knot nematode, Meloidogyne incognita J2 in-vivo and in-vitro on eggplant cv. Black Beauty (Solanum melongena L.). In laboratory experiments, all of the tested compounds caused significant mortality of the second larval stage (J2). It was, also, noticed that the tested compounds reduced egg hatching. Carvone, cuminaldehyde, thymol, geraniol, and citral showed the highest nematicidal activity among the tested monoterpenes in vitro. The results of greenhouse experiment clarified that the tested monoterpenes; carvone, cuminaldehyde, thymol, geraniol, and citral, significantly, reduced numbers of root galls, egg masses and population of nematodes of eggplant at concentration 250 mg/kg soil compared to the inoculated control. Carvone was the most effective treatment in reducing root galls, egg masses and final population of the nematode except for oxamyl. Results revealed that all of the tested treatments increased various measures of plant growth characters with the reduction in the root- knot infestation. Among all of the tested monoterpenes, carvone followed by cumminaldehyde were the most effective treatments to increase both fresh shoot & root weights and lengths. None of the compounds was phytotoxic at the tested treatments. Results stated that monoterpenes exhibited significant nematicidal activity in-vitro and in-vivo experiments and could be considered as useful natural namaticidal agents.