Metarhizium anisopliae Produces Dimethyl Disulfide and Dimethyl Trisulfide as Broad-Spectrum Volatile Nematicides

Metarhizium spp. are widely used as biocontrol agents against insect pests, but the chemical basis underlying their nematicidal activity remains largely unknown. Here, bioassay-guided fractionation and GC–MS identified dimethyl disulfide (DMDS) and dimethyl trisulfide (DMTS) as the major volatile nematicidal compounds produced by Metarhizium anisopliae . Both compounds exhibited concentration-dependent activity against three plant-parasitic nematodes (PPNs), with 24 h LC 50 values of 0.19–1.38 μg/mL for DMDS and 0.04–0.07 μg/mL for DMTS. In tomato pot trials, the fermentation broth achieved 79.49% control efficacy against Meloidogyne incognita , significantly higher than abamectin (68.24%). The GFP-labeled fungus colonized tomato roots and persisted in the rhizosphere for 60 days. Molecular docking and physiological assays suggested that DMDS and DMTS disrupt calcium homeostasis, impair mitochondrial function, and induce ROS accumulation. These findings provide new insight into the volatile-mediated nematicidal activity of M. anisopliae and support its development as an environmentally friendly bionematicide.