Suchergebnisse

Megachilidae bees are important pollinators in the Neotropical region, however information on the ecology and behavior of these species is still scarce. The objective of this study was to analyze the nesting biology of sympatric species in the União Biological Reserve, a remnant of Atlantic Forest in the southeastern Brazil. Our results indicated the occurrence of 17 species, representing significant richness compared to other areas in the Atlantic Forest. Five sympatric species built ¾ of all nests found and the architecture of their nests was studied including, for the first time, nests of a species of Megachile (Ptilosarus). The use of petals or leaf fragments in the construction of the nests was observed for species of Megachile (Chrysosarus), confirming previous data. The nesting activity period in the trap-nests occurred mainly in the rainy season, with different peaks among the species. The results indicate that the distinctive characteristics of the species, such as the type of material used in the nests, the dimensions of cavities, and the asynchronous nesting period, could be important for the niche differentiation of these sympatric species, allowing the maintenance and the survival of the most abundant Megachilidae populations in the area.

Studies on bee-plant interactions are relevant to the understanding of temporal patterns in neotropical communities. In isolated habitats such as inselbergs little is yet known about the temporal dynamics in the availability of fl oral resources and interacting bee. In the present study, the objective is to verify the eff ect of seasonality on the bee-plant interaction in an Atlantic Forest inselberg in southeastern Brazil. The bees were sampled monthly in the dry (April/2008-September/2008) and wet seasons (October/2008-March/2009) using an entomological net. A total of 322 bees of 33 species were captured on fl owers of 34 species of plants during the year. Bees richness was similar between seasons (22 species in the wet season and 21 in the dry season), but abundance was higher in the wet season (60% of individuals) and higher diversity occurred in the dry season. Augochloropsis sp1 were the most abundant species and visited the largest number of plant species at each season. In the interaction network, plants with the highest degree were distinct between the seasons. The number of possible interactions was higher in the dry season compared to the wet season and connectance was similar; nestedness however varied between the seasons. The composition of plant and bees species was distinct between the seasons, as well as the interactions between them, mainly due to the alteration in the composition of the plant species and the change in the choice of the bees for the floral resources between the seasons.

We investigated the plant-pollinator interactions of Passifloraceae occurring in fragments of lowland semi-deciduous Atlantic forest. We described floral biology, pollination syndromes and the pollinators of Passiflora alata, Passiflora kermesina, Passiflora suberosa, Passiflora malacophylla and Mitostemma glaziovii. We examined the robustness of the interaction networks to species loss, a plausible scenario resulting from forest fragmentation. The effects of pollination syndrome (flower size) on network robustness was also examined. Passiflora alata, P. malacophylla and P. suberosa were pollinated by bees of different corporal sizes. P. kermesina and M. glaziovii presented the highest diversity of visitors and were pollinated mainly by hummingbirds and butterflies, respectively. Through the analysis of the networks we differentiate the structures of the flower-visitor network with the 'true' plant-pollinator network. The robustness of the flower-visitor network to animal loss was generally high, but it declined when only true pollinators were included in the network. The sequential loss of plants from the flower-visitor network resulted in low robustness: the loss of key plants could have significant cascading effects on the animals feeding on them within the forest fragment. Future studies should consider the interactions between all flowering plants and animals in this habitat in order to guide conservation and management plans for these forest fragments.

We describe and discuss the composition, abundance and diversity of euglossine in three vegetation types of the Atlantic Forest (Lowland Seasonal Semideciduous, Submontane Seasonal and Dense Montane Ombrophilous Forest) in Rio de Janeiro state, Brazil, compare them to previous studies in the region and investigate the importance of the vegetation types, climatic and geomorphological factors on the species composition. Male euglossine bees attracted by fragrances were sampled monthly from August/2008 to July/2009 using entomological nets and traps. Euglossine bee communities exhibited differences in their species composition and abundance along the year and in the vegetation types. The precipitation, altitude and vegetation types demonstrated a significant influence on the ordination of the euglossine communities. Our study found differences in the composition of euglossine bee communities as well as in their patterns of abundance and dominance among different vegetation formations, stressing the importance of the conservation of landscape mosaics in the region.

Under standard greenhouse conditions, the tomato fruits of spontaneous self-pollination are expected to be of lower quality than those of bee pollination, as well as that simultaneously use different bee species which can complement pollination services. To test these hypotheses, we evaluated the complementarity of pollination services from the use of three native stingless bee species that have distinct foraging behaviors, Melipona bicolor Lepeletier 1836, Nannotrigona testaceicornis (Lepeletier 1836) and Partamona helleri (Friese 1900) during flowering of cherry tomatoes in greenhouses. Fruit quality parameters resulted from pollination experiments were measured and the acclimatization of the analyzed bee species was evaluated. Visits of M. bicolor and N. testaceicornis to the tomato flowers contributed significantly to the increase in the average weight, seed number, and thickness of the pericarp (only for N. testaceicornis) of the fruits, compared to the spontaneous self-pollination treatment. Partamona helleri, however, did not show any pollen collection behavior in the experimental conditions. Although N. testaceicornis do not perform the buzzing behavior, fruits from its pollination were equivalent to those fruits from pollination by M. bicolor. The simultaneous use of bee species with different flower-visiting behaviors can optimize tomato pollination in greenhouses, contributing significantly to the quality of the fruits and the increase of productivity and consequently the commercial value.