Rice Distinguishes Eggs of a Specialist versus Generalist Herbivores and Emits Species-Specific Volatiles to Recruit an Egg Parasitoid

Plants release herbivore-induced volatiles that attract parasitoid wasps. Whether plants can distinguish eggs of different insect species and mount targeted indirect defenses remains unclear. Here, we provide evidence that rice exhibits differential responses. Rice responds differently to eggs of its specialist pest species, the striped stem borer ( Chilo suppressalis, SSB), from eggs of two generalists, the Asian corn borer ( Ostrinia furnacalis, ACB) and the fall armyworm ( Spodoptera frugiperda, FAW). Notably, only SSB egg induces a volatile blend that strongly attracts the egg parasitoid Trichogramma japonicum . D-limonene and methyl salicylate (MeSA) were identified as two key attractants contributing to this differential attraction. Mechanistically, the response to SSB eggs triggers an oxidative burst, salicylic acid accumulation, and jasmonic acid suppression, which is associated with the activation of two biosynthetic genes, OsTPS46 and OsPAL3 . CRISPR-Cas9 knockout of either gene markedly reduces or even eliminates volatile emission and reduces parasitoid attraction, and exogenous application of the synthetic blend significantly restores this defect. Together, our work provides a detailed analysis of specific genetic and chemical components underlying differential parasitoid attraction in a major crop and identifies a two-gene module that may enable precision biocontrol strategies.