Nematicidal activity of crude extract from Torreya grandis against root-knot nematode Meloidogyne enterolobii and preliminary insights into its mechanism

Root-knot nematodes like Meloidogyne enterolobii cause severe crop losses, yet chemical nematicides pose environmental and health risks. This study explored the nematicidal activity and mechanism of Torreya grandis crude extract. In vitro assays showed 10.00 mg/ml and 5.00 mg/ml extracts killed 100 % of J2 juveniles within 12 and 24 h, respectively, with 10.00 mg/ml strongly inhibiting egg hatching (only 4 juveniles in 10 days) and triggering the highest avoidance response (index 0.47). The LC₅₀ values decreased over time, while LT₅₀ prolonged with lower concentrations. Greenhouse trials revealed the extract reduced tomato root-knot index, with a maximum control efficacy of 30.23 %. Mechanistically, it inhibited nematode acetylcholinesterase, carboxylic acid esterase, superoxide dismutase, and catalase activities. These results highlight T. grandis crude extract as a promising eco-friendly nematicide, laying the groundwork for developing plant-derived alternatives to chemical nematicides.