Impact of herbivore kairomones on plant growth, defense, and development

Despite substantial research exploring plant defense induction during and after herbivore attack, little is known about whether and how plants use pre-attack cues such as kairomones (herbivore-emitted chemicals not associated with attack that are detected by – and thus provide benefits to – a plant) to preemptively induce defense. Herbivore kairomones have recently been documented in multiple systems; slug/snail mucus, an easily obtained and manipulable kairomone, can be used to ask novel questions about plant risk perception and induced responses. The fact that slugs preferentially attack seedlings, a highly vulnerable life history stage, highlights the selective advantage of pre-attack mucus detection and response. I am working with researchers at Tufts University and The University of Wisconsin-Madison on research exploring whether different risk cues affect growth and defense of different-aged seedlings, how ontogenetic shifts in susceptibility determine patterns of responses, and the immediate and legacy consequences of risk perception and ontogeny in the field settings. These questions are asked using the slug Arion subfuscus and the sugar maple Acer saccharum in experiments exploring interactions between risk cue quality and seedling age over both short (~1 month) and long (>1 yr.) time periods. The manipulation of herbivore cues, ontogeny, and differential susceptibility within and across seasons explores whether current plant defense reflects the ‘ghost of herbivory risk past’; present-day defense may often only make sense in light of past information received by plants.