In vitro effectiveness of plant extracts on the mortality of root-knot nematodes

Objective: Identify plants with nematicidal potential to Meloidogyne enterolobii and Nacobbus aberrans species for their application in sustainable agricultural practices. Design/methodology/approach: Six aqueous extracts (AE) of Origanum vulgare, Foeniculum vulgare, Dracocephalum moldavica, Thymus vulgaris, Dysphania ambrosioides and Melissa officinalis leaves were evaluated for the control of second instar (J2) juveniles of Meloidogyne enterolobii and Nacobbus aberrans. The solution obtained was designated as standard (100%) and was diluted with distilled water to concentrations of 25, 50 and 100%. Sterile distilled water was included as a test sample. Each concentration was repeated 4 times, using 400 J2/concentration. Mortality observations were performed at 6, 24 and 48 h. A nonparametric factorial analysis was performed based on the use of aligned ranks under the R study statistical analysis. Results: The factorial analysis of variance of the main effects P (Plants) and T (Time) for the variable mortality of the J2 of M. enterolobii (Me) and N. aberrans (Na), indicated highly significant differences (p≤0.05) as well as interaction effect between P*T. All aqueous extracts evaluated at a concentration of 100% achieved higher mortality in J2 of Me at 24 hours of exposure and at 12 hours at a concentration of 25% in J2 of Na. Limitations on study/implications: This work is positioned as a fundamental starting point for future research in this field, and represents the first effort to propose the implementation of new plant species with nematicidal effect on Root-knot nematode. Findings/conclusions: Our results show for the first time the in vitro nematicidal activity of plant extracts of Dysphania ambrosioides, Melissa officinalis, Foeniculum vulgare and Thymus vulgaris against the nematodes M. enterolobii and N. aberrans. These findings make it necessary to continue with future research to evaluate their effectiveness under soil conditions, as well as metabolomic analysis aimed at identifying compounds responsible for this activity.