Co-infestation by two major pests suppresses phenylpropanoid defense and reprograms volatiles to facilitate stable cohabitation on rice

Classical ecological theory predicts that herbivorous species are in competition when they share the same host plant, yet in agricultural systems certain pest insects can stably coexist on the same plant, and even perform better when they feed together than if they feed alone. As yet, the molecular mechanisms underlying such collaborative cohabitation have remained unclear. Here we unravel how two major rice pests, the brown planthopper (BPH, Nilaparvata lugens) and the rice leaf folder (RLF, Cnaphalocrocis medinalis), achieve stable cohabitation by jointly suppressing plant chemical defenses.

Prior BPH feeding induced strong rice resistance that reduced RLF performance, whereas prior RLF feeding did not affect BPH. This asymmetric consequence of resistance induction was fully abolished when both pests initiated feeding simultaneously. Metabolomics and network analyses identified phenylpropanoid-derived chlorogenic acids and coniferin as key BPH-induced defense compounds detrimental to RLF but not BPH.