Trotamundos

BIOTROPICA 35(2): 181–188

2003

Ant Protection against Herbivory in Three Species of Tococa (Melastomataceae) Occupying Different Environments1
Fabian A. Michelangeli 2 L. H. Bailey Hortorium, Cornell University, Ithaca, New York 14853, U.S.A., and Cullman Molecular Systematics Program, Department of Ornithology, American Museum of Natural History, New York, New York 10024, U.S.A.ABSTRACT
The genus Tococa is comprised of 47 species of small trees and shrubs distributed from southern Mexico to Bolivia. About 30 of the species have ant domatia that develop at the base of the leaf blade or at the apex of the petiole. Ant exclusion experiments on three different species of Tococa occupying different environments were carried out to assess their effect in protecting the plantagainst herbivores. Additionally, ant behavior was monitored in control plants to study how they might be conferring protection against herbivory. Herbivory was significantly lower on control plants (ants maintained) than on experimental plants (ants removed), demonstrating the role of the ants as defenses against herbivores. Herbivory rates in open and disturbed areas were higher than in the forestunderstory. Ant exclusion experiments showed that both timid and aggressive ants protect their host plants against potential herbivores by killing or warding off scouts of leaf-cutter ants (Atta sp.) and removing the eggs of Lepidoptera and Coleoptera from the surface of the plants.

RESUMEN
El genero Tococa esta compuesto por 47 especies de arbustos y arboles pequenos distribuidos desde el sur deMexico ´ ´ ˜ ´ hasta Bolivia. Cerca de 30 especies poseen domacios que se desarrollan en la base de la lamina de la hoja o en el ´ apice del pecıolo. Se llevaron a cabo experimentos de exclusion de hormigas en tres especies de Tococa en distintos ´ ´ ´ habitat con el fin de evaluar su rol potencial de proteccion contra la herbivorıa. Adicionalmente, se observo el ´ ´ ´ ´ comportamiento de lashormigas en las plantas del grupo control con el fin de estudiar su papel como defensa contra los herbıvoros. Las diferencias en las tasas de herbivorıa entre plantas con y sin hormigas fue siempre significativa, ´ ´ demostrando ası el rol de las hormigas como defensa contra los herbıvoros. Ademas, en las zonas abiertas y secundarias, ´ ´ ´ la cantidad de herbivorıa fue siempre mayor que en el dosel delbosque. Estos experimentos tambien demuestran que ´ ´ tanto las hormigas tımidas como las agresivas protegen a las plantas que habitan, ya sea matando o ahuyentando los ´ exploradores de las hormigas cortadoras de hoja (Atta sp.) o removiendo los huevos de Lepidoptera y Coleoptera de la superficie de las plantas. Key words: ant behavior; Atta; Azteca; Crematogaster; forest–savanna ecotone; forestunderstory; gallery forest; gap; myrmecophytism; Tococa; Venezuela.

in which plants provide the ants with some type of structure that facilitates the establishment of the ant colony on the plant, and ants provide protection against potential herbivores and/or pruning of lianas and epiphytes. Additionally, the plants may provide the ants with food, Beltian bodies as in the case of Acacia orMullerian ¨ bodies in Cecropia. The structures inhabited by the ants are usually hollow chambers (usually referred to as ant domatia, myrmecodomatia, or simply doIS THE SYMBIOTIC ASSOCIATION BE TWEEN ANTS AND PLANTS

MYRMECOPHYTISM

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Received 31 May 2002; revision accepted 3 April 2003. Current address: Cullman Molecular Systematics Program, New York Botanical Garden, 200th St. and SouthernBlvd., Bronx, New York 10458, U.S.A.; e-mail: fabian@nybg.org

matia) located in a variety of plant organs, such as roots in Myrmecodia (Huxley 1986), stems in Cecropia (Janzen 1969) and Cordia (Davidson et al. 1989), thorns in Acacia (Janzen 1966), and leaves in Hirtella (Spruce 1908, Prance 1982). Some of the earlier studies on ant-plants considered the ants to be detrimental rather than...