Identification and fumigant effects of nematicidal volatile organic compounds produced by nematophagous fungi against root-knot nematodes

Plant-parasitic nematodes of the genus Meloidogyne, commonly known as root-knot nema- todes, pose a significant threat to global agricultural productivity. Due to concerns about environmental impact and human health risks, the use of commer - cially available synthetic nematicides has become increasingly restricted. Consequently, the search for natural molecules with nematicidal properties has emerged as a promising alternative. In this study, we found that nine nematophagous fungal iso- lates belonging to the genera Arthrobotrys, Mona- crosporium, Duddingtonia, and Pochonia produce volatile organic compounds (VOCs) with nematicidal activity against Meloidogyne incognita. The major VOCs, identified by SPME–GC–MS, exhibited high mortality rates against second-stage juveniles (J2) of M. incognita, with LC₅₀ values comparable to, and LC₉₅ values lower than, those of the commercial nematicide fluensulfone. All identified VOCs sig- nificantly inhibited egg hatching in vitro, and several compounds, at concentrations of 200 μg ml⁻ 1, nearly eliminated in vivo nematode reproduction in soy - bean plants under fumigation assays. Among them, 1-octen-3-ol, 3-octanone, and benzaldehyde showed the greatest potential as natural bionematicidal fumi- gants. This is the first report of nematicidal VOC pro- duction by A. cladodes, A. conoides, A. robusta, A. musiformis, and M. thaumasium.