A whole-plant perspective reveals unexpected impacts of above- and belowground herbivores on plant growth and defense

Authors: MUNDIM, FABIANE - University Of Florida; Alborn, Hans; VIEIRA-NETO, ERNANE - University Of Florida; BRUNA, EMILIO - University Of Florida

Submitted to: Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/11/2016
Publication Date: 1/10/2017
Citation: Mundim, F.M., Alborn, H.T., Vieira-Neto, E.H., Bruna, E.M. 2017. A whole-plant perspective reveals unexpected impacts of above- and belowground herbivores on plant growth and defense. Ecology. 98(1):70-78.

Interpretive Summary: It has been generally believed that plants can’t simultaneously invest in both growth and defense and thus this assumption has been central to the theoretical frameworks used to study the ecology and evolution of plant defense against herbivores. However experiments designed to test these frameworks have rarely included belowground herbivores. A scientist at the Chemistry group, USDA ARS CMAVE in collaboration with University of Florida scientists found that when the tropical shrub Solanum lycocarpum (Solanaceae) suffered aboveground herbivory by Spodoptera caterpillars it responded with aboveground growth as well as belowground defense. Similarly, belowground herbivory by the nematode Meloidogyne incognita resulted in root growth as well as elevated leaf defenses above ground. Thus in contrast to theoretical predictions plants can simultaneously invest in both growth and defense. These results emphasize the need for a ‘whole-plant’ perspective in theoretical and empirical evaluations of plant-herbivore interactions.

Technical Abstract: Tradeoffs between plant growth and defense are central to theoretical frameworks used to study the ecology and evolution of plant defense against herbivores. However, these frameworks, as well as the experiments designed to test them, rarely include the remarkable diversity of belowground herbivores. We experimentally challenged seedlings of the tropical shrub Solanum lycocarpum (Solanaceae) with either aboveground foliar herbivores (Spodoptera caterpillars) or belowground root herbivores (the nematode Meloidogyne incognita) and measured the resulting changes in plant growth rates, biomass allocation, and the concentration of defensive terpenoids in roots and leaves. We found that plants that suffered aboveground herbivory responded with aboveground growth but belowground defense. Similarly, belowground herbivory resulted in root growth but elevated defenses of leaf defenses. These results underscore the importance of belowground plant-herbivore interactions, and suggest that – in contrast to theoretical predictions – plants can simultaneously invest in both growth and defense. Finally, they emphasize the need for a ‘whole-plant’ perspective in theoretical and empirical evaluations of plant-herbivore interactions.