Integrated analysis of solvent-extractable secondary metabolites reveals multi-layered resistance to Helicoverpa armigera in chickpea crop wild relatives

The cultivated chickpea gene pool possesses limited resistance to the pod borer, Helicoverpa armigera , necessitating the discovery of novel defense-associated metabolites and resistance sources for sustainable pest management. Crop wild relatives (CWRs) represent a rich but underexplored reservoir of solvent-extractable secondary metabolites, some of which may function as candidate semiochemicals contributing to insect resistance. In this study, a diverse panel of chickpea CWRs, together with resistant and susceptible cultivated genotypes, was evaluated under multi-location field conditions and controlled laboratory bioassays to elucidate the role of secondary metabolites in defense against H. armigera . Several CWR accessions exhibited significantly reduced oviposition, larval survival, feeding damage, and larval weight gain, indicating the combined action of antixenosis and antibiosis mechanisms. Multivariate analyses identified three highly resistant genotypes, ICC 20209 ( Cicer cuneatum ), ICC 17318 ( C. judaicum ), and ICC 17152 ( C. pinnatifidum ), which consistently outperformed cultivated checks across environments and experimental assays. Gas chromatography-mass spectrometry (GC-MS) profiling revealed distinct hexane-extractable metabolite signatures in the resistant genotypes, characterized by enhanced accumulation of fatty acid-metabolites, particularly 9-octadecenoic acid (oleic acid) and tetradecanoic acd (myristic acid). These metabolites are implicated in insect behavioral modulation and host selection. Molecular docking and molecular dynamics simulations putatively demonstrated stable interactions between 9-octadecenoic acid and the H. armigera general odorant-binding protein 2 (GOBP2), suggesting that these metabolites may contribute to altered host recognition. In Y-tube assays, 9-octadecenoic acid reduced the orientation of both female and male moths in a dose-dependent manner, indicating repellent activity at higher doses. Collectively, our findings demonstrate that chickpea crop wild relatives harbor unique solvent-extractable chemical defenses and constitute an important reservoir of bioactive secondary metabolites associated with insect resistance. By integrating multi-location phenotyping, solvent-extractable metabolite profiling, computational analyses, and insect adult orientation assays, this study establishes a mechanistic framework that links specialized metabolism to resistance to H. armigera . These results provide valuable insights for the exploitation of wild germplasm in breeding programs and open new avenues for developing semiochemical-based and metabolite-informed strategies for sustainable insect pest management.