Fig. 2.

Ecological consequences of emitting and receiving volatile cues. The arrows indicate the direction of VOC transport. The boxes indicate the potential outcomes of the response and whether the emitter or receiver gains a beneficial (+) or a detrimental (-) effect on fitness. SAR indicates that the emitting plant may gain systemic acquired resistance. We refer to allelopathy as a phenomenon whereby the emitter releases chemicals that have detrimental effects on the performance of the receiver plant (Inderjit and Duke, 2003). Eavesdropping is the process whereby a receiver intercepts and uses information encoded in chemical cues that evolved to provide information to a different recipient (Karban, 2015). MBH indicates the mutual-benefits hypothesis, whereby the emitter and receiver benefit from the transport of VOC cues, irrespective of their relatedness, through the responses of receivers reducing the risk of herbivory (Kalske et al., 2019).