Trends
Hundreds of studies convincingly demonstrate functioning indirect defenses in wild plants, but breeding approaches have never considered the underlying traits (e.g., food rewards or shelter for carnivores, and volatiles that mediate information-based interactions) as desirable targets.
We argue that induced plant volatiles, owing to their multiple roles as signals, repellents, and antimicrobial compounds, bear an as-yet underused potential for biological control, and that future breeding efforts should enhance the capacity of crops to engage in tritrophic interactions.
We also present ecological and evolutionary considerations that can explain why the constitutive release of volatile compounds that have evolved as inducible defenses is not likely to work, and why extrafloral nectar is likely to represent a better food reward for carnivores than floral nectar.
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