In vitro Nematocidal Potential of Ricinus communis and Mangifera indica Leaf Extracts Against Root-Knot Nematodes (Meloidogyne spp.)

Abstract

Root-knot nematodes (Meloidogyne spp.) are among the most destructive plant-parasitic nematodes causing substantial yield losses in agricultural production worldwide. The extensive use of synthetic nematicides for their control has raised concerns regarding environmental pollution, human health risks, and the development of resistance, thereby necessitating the search for eco-friendly alternatives. This study evaluated the in vitro nematocidal activities of aqueous leaf extracts of Ricinus communis L. and Mangifera indica L. against second-stage juveniles (J2) of Meloidogyne spp. Nematodes were extracted from infected roots and rhizosphere soils of Musa spp. using the modified Baermann funnel technique. Aqueous leaf extracts were prepared by maceration and screened for phytochemical constituents. The extracts were tested at concentrations of 40, 60, 80, and 100 mg mL⁻¹, while distilled water served as the control. Nematode mortality was assessed at 24-hour intervals over a 120-hour exposure period. Data were subjected to two-way analysis of variance and treatment means separated using the Least Significant Difference (LSD) test at the 5% probability level. Phytochemical screening revealed the presence of alkaloids, flavonoids, tannins, saponins, phenols, terpenoids, and steroids in both plant extracts, suggesting their potential nematocidal properties. The extracts exhibited concentration- and time-dependent nematocidal activities, with mortality increasing significantly (P < 0.05) as concentration and exposure duration increased. Ricinus communis consistently demonstrated greater nematocidal activity than M. indica at all concentrations and exposure periods. The highest mortality rates were recorded at 100 mg mL⁻¹ after 120 h of exposure, resulting in 83.44% and 65.94% mortality for R. communis and M. indica, respectively. The findings indicate that both plant extracts possess promising nematocidal properties, with R. communis showing superior efficacy, and may serve as environmentally sustainable alternatives to synthetic nematicides for the management of root-knot nematodes.