Harnessing microbial volatiles for the management of root-knot and root-lesion nematodes

Plant-parasitic nematodes are major constraints to global crop yield and quality, and increasing restrictions on nematicides highlight the need for effective, environmentally compatible alternatives. Here, we evaluated the in vitro and in vivo nematicidal activity of Formula B, a biorational mixture of volatile organic compounds (VOCs) derived from Muscodor spp., against the root-knot and root-lesion nematodes, in comparison with a commercial fluopyram-based nematicide (Velum, Bayer). In vitro assays demonstrated that Formula B significantly reduced nematode motility compared with the water control across all concentrations. For M. incognita, mortality reached 90% after 6 hours at 0.5% and 1% concentrations, consistent with reduced cucumber gall formation. Similarly, P. neglectus showed strong dose- and time-dependent sensitivity. Short exposures (20 minutes to 1 hour) caused partial immobilization and reduced movement, while 24-hour exposure resulted in complete loss of normal motility and high to complete mortality at concentrations above 0.25%. In vivo experiments confirmed these effects. On wheat, Formula B reduced P. neglectus survival and root penetration at all concentrations, with the greatest suppression at 0.5% and 1%, corresponding to 68% and 96% reductions in root invasion, respectively. On cucumber, M. incognita infection was strongly reduced, with 0.5% and 1% treatments decreasing gall index by 93% and 67, respectively, compared with the control. Overall, Formula B exhibited strong nematicidal activity against both sedentary and migratory endoparasitic nematodes by reducing motility, survival, and host infection. These results suggest that VOC-based formulations are promising tools for nematode management, although further research is needed to evaluate their field performance and scalability.