Communication between undamaged plants can elicit changes in volatile emissions from neighbouring plants, thereby altering their susceptibility to aphids

Plant volatiles play an important role in intra- and interspecific plant communication, inducing direct and indirect defenses against insect pests. However, it remains unknown whether volatile interactions between undamaged cultivars alter host plant volatile emissions and their perception by insect pests. Here, we tested the effects of exposure of a spring barley, Hordeum vulgare L., cultivar, Salome, to volatiles from other cultivars: Fairytale and Anakin. We found that exposing Salome to Fairytale induced a significantly higher emission of trans-beta-ocimene and two unidentified compounds compared when exposed to Anakin. Aphids were repelled at a higher concentration of trans-beta-ocimene. Salome exposure to Fairytale had significant repulsive effects on aphid olfactory preference, yet not when Salome was exposed to Anakin. We demonstrate that volatile interactions between specific undamaged plants can induce changes in volatile emission by receiver plants enhancing certain compounds, which can disrupt aphid olfactory preferences. Our results highlight the significant roles of volatiles in plant-plant interactions, affecting plant-insect interactions in suppressing insect pests. This has important implications for crop protection and sustainable agriculture. The airborne interactions between certain undamaged spring barley (Hordeum vulgare L.) cultivars induce changes in volatile emission in receiving plants by enhancing the production of certain ideal volatile organic compounds. These changes trigger strong repellent effects on aphids (Rhopalosiphum padi L.), suggesting the significant roles of volatile-mediated plant-plant interactions in the development of integrated pest management for sustainable agriculture practices.