Semiochemical potential of elicitor–induced plant volatiles strengthen wheat defense and enhance Trichogramma-mediated biological control of pink stem borer

Pink stem borer ( Sesamia inferens ) has become a major constraint to wheat production in South Asia, and the increasing reliance on synthetic insecticides has raised concerns related to resistance development, ecological safety, and production sustainability. This study evaluated the efficacy of four plant defense elicitors—jasmonic acid (JA), salicylic acid (SA), methyl salicylate (MeSA), and chitosan—for managing S. inferens under natural field conditions during two winter seasons. Elicitors were applied as foliar sprays at 35 and 45 days after sowing, and their effects on pest incidence and grain yield were assessed. JA at 5 mM was consistently the most effective treatment, reducing dead-heart and white-ear symptoms by 31.7% and 27.9%, respectively, and increasing grain yield by 28.9% compared with the untreated control. SA and MeSA provided moderate suppression (15–24%), whereas chitosan showed only marginal effects. Gas chromatography–mass spectrometry analysis revealed that JA application and herbivory induced a more diverse and distinct volatile blend than that emitted by healthy plants, with hydrocarbons such as eicosane, octadecane, and n-hexadecanoic acid markedly elevated. Laboratory bioassays demonstrated that these volatiles significantly enhanced the foraging efficiency of the egg parasitoid Trichogramma chilonis , producing parasitism rates comparable to natural kairomonal cues. The integrated field, chemical, and behavioural findings demonstrate that JA-induced volatile signaling provides dual benefits: direct suppression of stem borer injury and indirect enhancement of biological control. JA therefore represents a practical, eco-friendly input for strengthening integrated pest management strategies in wheat. • Foliar application of jasmonic acid (JA, 5 mM) reduced dead-heart and white-ear incidence by 31.7% and 27.9%, respectively, and increased wheat grain yield by 28.9%. • JA and herbivory induced a distinct volatile blend, with hydrocarbons such as eicosane, octadecane, and n-hexadecanoic acid showing strong elevation. • Synthetic analogues of major JA-induced volatiles enhanced Trichogramma chilonis parasitism to levels comparable to natural kairomones in laboratory assays. • JA demonstrated dual defensive benefits by providing direct suppression of S. inferens and strengthening indirect defence through improved parasitoid foraging efficiency.