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Epidendrum denticulatum (Orchidaceae) produces nectar on the petioles of buds, flowers, and fruits (extrafloral nectaries) but no nectar is found on its flowers, and it is probably a deceptive species. In the Brazilian Atlantic rainforest, some aspects of both the ecology and behavior of Camponotus sericeiventris (Formicinae) and Ectatomma tuberculatum (Ponerinae), two ant species foraging on E. denticulatum extrafloral nectaries, were investigated. Both experiments, using termites as baits and field observations, suggest that these ant species are able to prevent reproductive organ herbivory, without affecting pollinator behaviour. Since a low fruit set is often cited as a characteristic of the family, especially for deceptive species, ants attracted to orchid inflorescences protect reproductive structures and increase the probability of pollination success. Epidendrum denticulatum flowers were visited and probably pollinated by Heliconius erato (Nymphalidae) and Euphyes leptosema (Hesperiidae).Key words: ant-plant interaction, foraging behaviour, extrafloral nectaries, pollination ecology. RESUMO Formigas visitam nectáreos de Epidendrum denticulatum (Orchidaceae) em uma área deMata Atlântica: efeitos sobre herbivoria e polinização Epidendrum denticulatum (Orchidaceae) produz néctar nos pecíolos de botões florais, flores e frutos (nectáreos extraflorais), mas não em suas flores, e provavelmente "engana" seus polinizadores. Numa área de Mata Atlântica, investigamos alguns aspectos da ecologia e comportamento das formigas Camponotus sericeiventris (Formicinae) e Ectatomma tuberculatum (Ponerinae), ambas encontradas forrageando em nectáreos extraflorais de E. denticulatum. Tanto experimentos usando cupins como iscas quanto observações de campo sugerem que ambas as espécies de formiga têm a dupla capacidade de limitar a herbivoria dos órgãos reprodutivos da espécie estudada, sem interferir no comportamento dos polinizadores. Uma vez que baixa taxa de frutificação é característica das orquídeas, principalmente de espécies sem néctar floral, as formigas atraídas para suas inflorescências estão protegendo as estruturas reprodutivas e aumentando a probabilidade de sucesso de polinização. As flores de E. denticulatum são visitadas e provavelmente polinizadas por Heliconius erato (Nymphalidae) e Euphyes leptosema (Hesperiidae).Palavras-chave: interação planta-formiga, comportamento de forrageamento, nectáreos extraflorais, ecologia de polinização.

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-The exotic tree Muntingia calabura L. (Muntingiaceae), a species native to Central America, is used as fish feed and fiber and cellulose production in Brazil. This study was carried out in urban areas and verified the reproductive biology of this plant species. Flower and fruit morphology, compatibility system, reproductive phenology, pollination and frugivore animals, and germination of disseminated seeds were recorded by standard field and laboratory procedures. This tree is self-compatible and autonomously self-pollinated, with its flowers being mainly visited by bees and its fruits consumed by birds and bats. Germination of its dispersed seeds is fast and occurs at a high rate. The results of this work suggest that M. calabura is very adaptable to cultivated areas,thus being an excellent choice for urban reforestation. However, its reproductive characteristics place this plant as an invasive species with significant potential in southeastern Brazil.Keywords: Plant reproduction, heterogeneous reforestation and urban ecosystems. ECOLOGIA REPRODUTIVA DA ÁRVORE EXÓTICA Muntingia calabura L. (MUNTINGIACEAE) NO SUDESTE DO BRASIL RESUMO -A árvore exótica Muntingia calabura L. (Muntingiaceae) é nativa da América Central e, no

Fruiting plants that attract frequent visits by fruit-eating birds tend to be predictable patches for a predator. Consequently, the risk of a predator attack increases the longer a bird stays on a fruiting plant. We tested whether large and cryptic species of fruit-eating birds spend more time per feeding visit than smaller and conspicuous ones in fruiting plants of the Brazilian Cerrado. Data were obtained from the literature for eight fruiting plant species and from field observations of birds feeding on fruits of Zanthoxylum rhoifolium (Rutaceae). We searched for a positive linear relationship between the mean visit time and the total length of the species, considering bird color as a covariate. Feeding visits of the large and cryptic bird species lasted longer than feeding visits of small and conspicuous species. Large birds may be safer from predators because large predators are less common. Cryptic birds may be difficult to be detected by predators and, consequently, may be less likely to be attacked by predators than conspicuous birds. Thus, our results provide support to the hypothesis that vulnerable bird species spend less time foraging in fruiting plants.