Sebastião Laroca

Floral biology of Stachytarpheta maximiliani Scham. (Verbenaceae) and its floral visitors

This study describes the reproductive system of Stachytarpheta maximiliani (Verbenaceae), including its floral biology, nectar and pollen availability and insect foraging patterns, identifying whose species act as pollinators. It was carried out in a Brazilian Atlantic rain forest site. Observations on the pollination biology of the Verbenaceae S. maximiliani indicate that their flowering period extends from September through May. Anthesis occurs from 5:30 a.m. to 5:00 p.m. and nectar and pollen are available during all the anthesis. Many species of beetles, hemipterans, flies, wasps, bees and butterflies visit their flowers, but bees and butterflies are the most frequent visitors. The flowers are generally small, gathered in dense showy inflorescences. A complex of floral characteristcs, such as violet-blue color of flowers, long floral tubes, without scents, nectar not exposed, high concentration of sugar in nectar (about 32%), allowed identification of floral syndromes (melittophily and psicophily) and function for each visitor. The bees, Bombus morio, B. atratus, Trigonopedia ferruginea, Xylocopa brasilianorum and Apis mellifera and the butterflies Corticea mendica mendica, Corticea sp., Vehilius clavicula, Urbanus simplicius, U. teleus and Heraclides thoas brasiliensis, are the most important pollinators.

Coexistência entre abelhas sem ferrão e formigas: ninho de Paratrigona myrmecophila (Apidae) construído em ninho de Camponotus senex (Formicidae)

A nest of Paratrigona myrmecophila Moure, found in a nest of Camponotus senex (Fr. Smith), is described. Besides records on nest structures, some notes on interspecific interactions, nest defense, population size, honey organoleptic properties, and comments on the coexistence of these two organisms are provided.

Diurnal anthophilous fauna in Brazilian Chaco vegetation: phenology and interaction with flora

Phenology is the basis for understanding the life cycle of plants or animals throughout the year. Thus, we surveyed diurnal anthophilous fauna on plant species in the Brazilian Chaco to determine (1) groups of floral visitors and occurrence; (2) richness and abundance of fauna in relation to flowering flora and meteorological variables; (3) groups of visitors that pollinate or thieving flora; (4) distribution of herbaceous and woody strata throughout the year of flowering; (5) variation in flowering as a whole community, in the context of abiotic factors; and (6) the predominant plant families and species. We sampled eight groups of floral visitors, totalling 105 sampled species and 644 specimens. The flies and bees were the richest groups, with bees forming the most abundant group. The phenology of the fauna and flora was not clustered and exhibited a continuous and bimodal flowering. The abundance and richness of floral visitors were positively related to the quantity of plant species and flowering, as well as rainfall. Herbaceous and woody strata are important for the maintenance of anthophilous fauna throughout the year. Plant species with the highest abundance and the longest flowering period presented the highest richness and/or abundance of floral visitors. The percentage of pollination was higher than that of resource theft. Bees and flies were the main groups of pollinators, whereas flies were the main thieves. The present survey is only a starting point for future studies on the networks of interactions between plants and their floral visitors in the Brazilian Chaco.

Phenology and pollination ecology of Prosopis rubriflora (Leguminosae, Mimosoideae), a species from the semi-arid Brazilian Chaco

Prosopis L. is particularly rich and important in the Chaco region where forest vegetation currently persists as fragments. Its species are very important for the conservation and management of Chaco vegetation, and understanding their phenology and reproductive biology is essential. Here, we studied the phenology and pollination biology of P. rubriflora Hassl. in the Brazilian Chaco compared to other species of the genus. Differing from other Prosopis species, P. rubriflora is evergreen, and most phenophases are nonseasonal and bimodal (except fruiting), with a continuous pattern. Prosopis rubriflora is andromonoecious, but only weakly, since plants produce relatively few staminate flowers. Flowers showed three floral stylar phenotypes: short, medium and long style. Short-style flowers are functionally staminate because the stigma is nonreceptive. To compensate for the small size of P. rubriflora red brush flowers, attraction is compressed and transferred to the spike, which functions as a collective pollination unit. This compression may favour self- and intraplant pollination, which may reduce and/or prevent the occurrence of protogyny and partial, i.e. temporal, herkogamy in hermaphrodite flowers. Prosopis rubriflora has generalist pollination, but differs from the other Prosopis species because it is also pollinated by hummingbird, most likely due to its “ornithophilous” characteristics. This species is the first of the genus recorded as pollinated by hummingbirds. Although the exotic bee Apis mellifera L. presents high frequency of visit, this bee is not effective pollinator, due to its foraging style that does not favour cross-pollen flow. Native insects and hummingbird species are main pollinators because they present trapline foraging.