Temporal variation in the composition of ant assemblages (Hymenoptera, Formicidae) on trees in the Pantanal floodplain, Mato Grosso do Sul, Brazil. In this paper we investigate how seasonal flooding influences the composition of assemblages of ants foraging on trees in the Pantanal of Mato Grosso do Sul. During the flood in the Pantanal, a large area is covered by floods that are the main forces that regulate the pattern of diversity in these areas. However, the effects of such natural disturbances in the ant communities are poorly known. In this sense, the objective of this study was to evaluate the effect of temporal variation in assemblages of ants foraging on trees in the Pantanal of Miranda. Samples were collected during a year in two adjacent areas, one who suffered flooding during the wet period and another that did not suffer flooding throughout the year. In 10 sites for each evaluated habitat, five pitfall traps were installed at random in trees 25 m apart from each other. In the habitat with flooding, the highest richness was observed during the flooding period, while there was no significant change in richness in the area that does not suffer flooding. The diversity of species between the two evaluated habitats varied significantly during the two seasons. Most ants sampled belong to species that forage and nest in soil. This suggests that during the flood in flooded habitats, ants that did not migrate to higher areas without flooding adopt the strategy to search for resources in the tree canopy.

Os hábitos alimentares de Bryconamericus stramineus foram estudados em riachos da sub-bacia do rio Guiraí, no estado de Mato Grosso do Sul, centro-oeste do Brasil. As amostragens foram realizadas bimestralmente em sete riachos na bacia do rio Guiraí, Alto Rio Paraná, de outubro/2006 a agosto/2007. Foram capturados 960 exemplares. As amostragens foram divididas em estação chuvosa e estação seca. B. stramineus apresentou hábito alimentar insetívoro; a espécie utilizou 17 itens alimentares, sendo que a tática de consumo das presas variou entre as estações a as localidades. Durante a estação chuvosa nos estômagos prevaleceram as Ordens Hymenoptera, Diptera e Coleoptera, durante a seca predominaram as Ordens Megaloptera e Diptera. Em todos os riachos analisados, B. stramineus apresentou dieta basicamente composta por insetos, sendo os demais itens consumidos ocasionalmente, confirmando a literatura.

Feeding habits of Bryconamericus stramineus were described in different streams of Guiraí River Sub-basin in Mato Grosso do Sul State, Mid-West of Brazil. Fishes were sampled bi-monthly between October/06 and August/07 in seven streams and the samples were separated in two seasons: dry and wet. A total of 960 individuals were captured. B. stramineus showed an insectivore feeding habit, consuming seventeen food items. The feeding tactic of preys capture varied between the seasons and the locations. During the wet season the most important items were Hymenoptera, Diptera and Coleoptera, while Megaloptera and Diptera were the most important during dry season. In all analyzed streams, B. stramineus showed a diet basically composed by insects; the other items spent sometimes, corroborating the literature.