In vitro assessment of Bionectria ochroleuca metabolites: A promising approach for controlling root-knot nematode, Meloidogyne incognita

Meloidogyne incognita, a highly destructive root-knot nematode, causes substantial crop losses worldwide by infesting plant roots, which disrupts nutrient and water uptake. This pest is notoriously challenging to manage due to its broad host range and growing resistance to many chemical nematicides, emphasizing the urgent need for sustainable, eco-friendly alternatives. In this context, the current study investigated the nematicidal potential of secondary metabolites derived from the entomopathogenic fungus, Bionectria ochroleuca against M. incognita. The in vitro assays demonstrated a dose- and time-dependent inhibition of egg hatching and juvenile survival. At a crude metabolite concentration of 100%, egg hatching was reduced to 5.64% and juvenile mortality increased to 95.4% after 72 h. Gas Chromatography-Mass Spectrometry (GC-MS) analysis identified key metabolites, including palmitic acid, butanedioic acid, lactic acid, and oleic acid, which appear to inhibit nematode growth through mechanisms that impair cell membrane integrity, disrupt energy metabolism, and interfere with essential metabolic pathways. Further, metabolite enrichment analysis revealed their involvement in the biosynthetic pathways, such as unsaturated fatty acids, galactose metabolism, and phenylalanine metabolism. Molecular docking studies supported these findings by showing high binding affinities of these metabolites to virulent nematode proteins, including Cytochrome c oxidase subunit 1 and NAD(H) oxidase, suggesting interference with essential biological processes within the nematode. Overall, these findings position the metabolites of B. ochroleuca as promising candidates for managing nematode infestations, offering a potent alternative to chemical nematicides and thereby contributing to sustainable agricultural practices.