Materials and methods
Characterizing plant responses to herbivory: direct
induction vs. priming, systemic vs. local responses
Chemical defense responses can result from direct induction,
such that the levels are higher after the initial herbivory
or cue of herbivory; and/or they can be primed,
such that levels of defense are higher or more rapid after
subsequent herbivore attack (Frost et al. 2008). In the first
experiment below, we sample leaves only after herbivory,
allowing us to measure induced defenses elicited by vibration,
but not to separate out direct effects vs. priming. In
the second experiment, we include a no-herbivory treatment,
allowing us to separate out priming from direct
effects of chewing vibrations on plant responses. Induced
responses can also be local, occurring only in tissues near
the site of herbivory, or systemic, occurring over a larger
spatial scale within the plant (Kessler and Baldwin 2002).
Chewing vibrations are propagated rapidly to other leaves