, Volume 165, Issue 2, pp 417–425 | Cite as

Is extrafloral nectar production induced by herbivores or ants in a tropical facultative ant–plant mutualism?

  • R. J. Bixenmann
  • P. D. Coley
  • T. A. Kursar
Plant-Animal interactions - Original Paper


Many plants use induced defenses to reduce the costs of antiherbivore defense. These plants invest energy in growth when herbivores are absent but shunt energy to defense when herbivores are present. In contrast, constitutive defenses are expressed continuously regardless of herbivore presence. Induction has been widely documented in temperate plants but has not been reported from tropical plants. Most tropical plants have higher, more constant herbivore pressure than temperate plants. In this situation, it is hypothesized that constitutive defenses rather than induced defense would be favored. Using natural herbivores of four species of Inga saplings on Barro Colorado Island, Panama, herbivore presence was crossed with ant presence to determine their effects on extrafloral nectar production. Analysis of nectar samples revealed that Inga species do not induce nectar production in response to herbivores. This result is not due to an inability of the plants to respond, as the plants in this study increased nectar production in response to light and ant presence. Contrary to most induction experiments with temperate ecosystem plants, these results demonstrate that tropical plants do not induce one type of defense, and they suggest that the most adaptive defense strategies are different for the two ecosystems.


Constitutive defense Inga Facultative mutualism Plant–insect interaction Herbivory 



This project was supported by short-term awards from the Smithsonian Tropical Research Institute, a Grants-in-Aid of Research award from Sigma Xi (RJB) and funding from NSF grants DEB-0640630, DEB-0234936, and OISE-0531803 (PDC and TAK). The field work would not have been possible without the help of our field assistants: Laura Jara, Venicia Cerrud, and Aneth Sarmiento. RJB would like to thank Tania Brenes-Arguedas and John Lokvam for their help during the initial stages of GC method development. We would like to thank all the friends and colleagues on BCI for their ideas and conversation regarding this project and ecology in general. We would also like to thank Joshua Tewksbury and one anonymous reviewer for comments that improved the quality of this paper. The field portion of this study complies with the current laws of the Autoridad Nacional del Ambiente de la Republica de Panama.


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Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  1. 1.Department of BiologyUniversity of UtahSalt Lake CityUSA

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