PARENT SESSION
Friday, August 11, 8:00-11:30 am
COS 106 - Species interactions: mutualism, symbiosis, and parasitism
L-3, Lobby Level, Cook Convention Center
Presiders: L Altfeld
Leaf volatiles and the defensive responses of Neotropical plant-ants: evidenced for host-plant specificity.
Bruna, Emilio *,1, 2, 3, Darrigo, Maria Rosa 3, Furuya Pacheco, Angela 3, Vasconcelos, Heraldo 3, 4, 1 Department of Wildlife Ecology & Conservation, Gainesville, FL, USA2 Center for Latin American Studies, Gainesville, FL, USA3 Biological Dynamics of Forest Fragments Project, Manaus, AM, Brazil4 Instituto de Biologia, Uberlanida, MG, Brazil
ABSTRACT- Ant species that defend plants from herbivores in exchange for rewards such as food or shelter are a defining characteristic of tropical forests and these interactions have become model systems with which to study the evolutionary ecology of mutualisms. In many ant-plant mutualist systems, ants patrol the leaves and stems of their host-plants and search for herbivores. Such patrolling can be inefficient, however, since herbivores are often at low density and their activity is unpredictable both spatially and temporally. It has therefore been argued that there should be strong selection for rapid and efficient systems of ant-plant communication that would both eliciting defensive responses and direct workers to sites of herbivore activity. Because ants use elaborate systems of chemical communication, several authors have suggested that chemical volatiles emitted by damaged plants may be an important class of stimulatory cue. Although there is mounting evidence to support this hypothesis, one key issue that has yet to be addressed is the potential for specificity in ant responses to their host-plant volatiles. We challenged colonies of two Amazonian plant-ants, Azteca sp. and Pheidole minutula, with extracts of leaf tissue from their host-plant species, other sympatric ant-plant species, and non-myrmecophytic taxa. We found that ants responded rapidly and dramatically to the application of host-plant extracts. Furthermore, these responses were always significantly greater than the response to extracts from other myrmecophytic plants. While both Azteca sp. and P. minutula responded to extracts of non-myrmecophytic plant species, the intensity of these responses was generally low. These results provide evidence that ant-plants contain species-specific volatiles designed to elicit plant defensive responses, in addition to a suite of generalized volatiles common to many plant species.
Key words: ant-plants, mutualisms, Azteca