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

Abstract Plant-parasitic nematodes of the genus Meloidogyne , commonly known as root-knot nematodes, pose a significant threat to global agricultural productivity. Due to concerns about environmental impact and human health risks, the use of commercially 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 isolates belonging to the genera Arthrobotrys , Monacrosporium , 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 significantly inhibited egg hatching in vitro, and several compounds, at concentrations of 200 μg ml⁻ 1 , nearly eliminated in vivo nematode reproduction in soybean plants under fumigation assays. Among them, 1-octen-3-ol, 3-octanone, and benzaldehyde showed the greatest potential as natural bionematicidal fumigants. This is the first report of nematicidal VOC production by A. cladodes , A. conoides , A. robusta , A. musiformis , and M. thaumasium .