Plant communication in a widespread goldenrod: keeping herbivores on the move

Abstract

Summary Plant communication has been documented in over 35 plant species spanning 16 families to date; however, the underlying mechanisms through which it shapes plants' ecological interactions remain less clear. Using a combination of field/laboratory bioassays, headspace volatile and leaf chemical analyses in tall goldenrod (Solidago altissima), we tested the hypothesis that plant‐to‐plant communication affects the performance, feeding and movement behaviour of herbivores by changing plants' chemical phenotypes. We found that plant communication accelerates herbivore movement between host plants while simultaneously reducing herbivory. This suggests that plant communication can limit herbivore loads by keeping herbivores on the move between host plants. We demonstrate that volatile chemicals emitted from herbivore‐attacked plants are sufficient to explain metabolic responses in and ecological consequences for the exposed neighbour plant. Volatile profiles of beetle (Trirhabda virgata)‐damaged and undamaged plants show substantial compositional differences, especially in sesquiterpene emission, indicating that these differences have the potential to provide neighbouring plants with specific information about herbivores in the vicinity. Despite qualitative and phenological differences in plants' metabolic responses to herbivory‐induced volatile organic compounds (VOCs) and feeding herbivores, herbivores nonetheless respond similarly to directly damaged plants and plants exposed to VOCs from damaged neighbours as if they were of equivalently poor quality. This study suggests that by enlarging the spatial scale at which induced resistance affects the distribution of plant chemical phenotypes in plant populations, VOC‐mediated plant communication alters the movement behaviour and performance of herbivores. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.12793/suppinfo is available for this article.

When does it pay off to prime for defense? A modeling analysis

“…Primed plants have been shown to exhibit faster and/or stronger responses to herbivore attack compared with plants that do not prime, and priming can lead to decreased caterpillar growth rates (Peng et al, 2011), increased pathogen resistance (van Hulten et al, 2006;Walters et al, 2008) and possibly increased movement of insect herbivores to more palatable plants (Morrell & Kessler, 2016). Therefore, priming is hypothesized to be beneficial for a plant as it may lead to a faster response to the upcoming attack (hereafter called the trigger event), while its costs are estimated to be relatively low compared with immediate defense (Bruce et al, 2007;Frost et al, 2008).…”

Resource co-limited growth in fluctuating environments

“…Nutritional heterogeneity depends on various natural or anthropogenic factors. In agroecosystems for example, herbivore attacks on plants induce the production of volatile chemical signals that prompt chemical defenses in undamaged plants (Morrell & Kessler 2017). Such induced responses increase nutritional heterogeneity of individual plants or groups of aggregated plants for herbivores (Karban 2017).…”

Facing global change: the millennium challenge for plant scientists

“…This indicates spreading the risk of herbivory to neighbours as a fitness‐optimizing strategy. The high variability of VOC types and levels in the field suggests the possibility of herbivore‐driven natural selection on chemical communication (Morrell & Kessler, ). This might modulate crop adaptability to newly introduced pests.…”