International audiencePollination is an important ecosystem service, especially to self-sterile crops as passion fruit, which depends on the large solitary bee for fruit set. We estimated the species richness of pollinators of yellow passion fruit in Central Brazil and examined whether there was any association with crop yield. We recorded 27 bee species on passion fruit flowers in commercial orchards in the region, from 2004 to 2007. Some 17 species were classified as pollinators (12 as effective and 5 as occasional pollinators). Species richness and frequency of pollinators were positively correlated with reproductive efficacy. Hand pollination substantially increased average fruit set (from 23.3% to 69.8%). Our results indicated that, although native pollinators still maintain economically viable natural fruit set in the region, pollination can be sustained and even enhanced by promoting conservation and management of bee diversity

Detailed studies of the behavior of pollinators allow insights into pollination mechanisms and may indicate which pollinators are more efficient for a particular plant species. Our aim was to evaluate if Melipona fasciculata is an efficient pollinator of eggplant (Solanum melongena L., Solanaceae) in greenhouses. We analyzed (1) the colony foraging pattern of M. fasciculata in greenhouses, (2) the behavior of bees during the visits to flowers, and (3) fruit set and fruit quality after different pollination treatments (hand pollination: autogamy, geitonogamy, xenogamy; bee pollination). Our results show that M. fasciculata is an efficient pollinator of eggplants and, consequently, may be a viable alternative to bumblebees in Brazil.

Floral scent is an important component of the trait repertoire of flowering plants, which is used to attract and manipulate pollinators. Despite advances during the last decades about the chemicals released by flowers, there is still a large gap in our understanding of chemical communication between flowering plants and their pollinators. We analyzed floral scents of guarana (Paullinia cupana, Sapindaceae), an economically important plant of the Amazon, using chemical analytical approaches, and determined the attractiveness of the scent to its nocturnal bee pollinators using behavioral assays in the field. Pollen loads of attracted bees were also analyzed. Inflorescences of guarana emit strong scents, both during day and at night, with some semi-quantitative differences between day- and night-time scents. Synthetic scent mixtures containing some of the identified floral scent components, including the most abundant ones, i.e., linalool and (E)-β-ocimene, successfully attracted the nocturnal Megalopta bee pollinators. Pollen analyses revealed that many of the attracted bees had pollen grains from previous visits to guarana flowers on their bodies. Overall, our data show that guarana flowers attract nocturnal bee visitors by their strong scents and suggest that the chemical communication between this plant and its pollinators is a key component in crop production of this economically important plant species.

The foraging success of a bee species is related to a combination of climatic factors and resource availability. Here, we analyzed how food storage by the stingless bee Scaptotrigona aff. depilis relates to the seasonal variation in floral resources availability in a tropical environment with two well-defined seasons. We found a positive relationship between the amount of food stored and resource availability, suggesting that colonies intensify food collection in the season with higher food availability (rainy season). This ensures the perennial state of stingless bee colonies during the dry season (food scarcity and lower ambient temperatures). Bees collected pollen from at least 60 plant species, but food pots were dominated by just nine plants. Additionally, S. aff depilis attempted to unevenly use the plant species for food storage in the rainy season, which indicates that the colonies maximize their food intake as soon as resources are available.

-Unpredictable environments are a challenge to highly eusocial bees because unreliable food availability, owing mainly to seasonally unpredictable precipitation rates, renders the maintenance of permanent colonies difficult. Here, we investigated the strategy of the stingless bee Melipona subnitida to cope with elevated temperatures and extended, irregular periods of drought in the Brazilian tropical dry forest. We found a high association between colony behaviour (pollen foraging and brood production) and environmental parameters (abiotic factors and availability of pollen sources), suggesting that colonies tightly adjust their activities to the respective environmental conditions. This minimises unnecessary costs related to foraging and brood rearing when forage availability is low. Additionally, M. subnitida selectively foraged at the most lucrative pollen-sources (massflowering trees, plants with poricidal flowers), which indicates that the colonies maximise their food intake as soon as resources are available.Caatinga / floral resources / pollen foraging / brood-cell construction

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In spite of playing an important ecological role as pollinators of tropical ecosystems, orchid bees are still poorly known regarding their floral resources. Aiming at a better comprehension of the importance of different plants visited by the Euglossini and, consequently, their role in the maintenance and reproduction of plant species in tropical ecosystems, this study aimed at identifying the flowers visited by those bees in two different areas of the Atlantic Forest in the northern coast of the state of São Paulo, Brazil. Sampling was carried out from August 2007 to July 2009 in two coastal ecosystems in Ubatuba, Brazil. In order to obtain information on flower resources collected by Euglossini beesin loco, all bees observed on flowers were collected, pollinaria of Orchidaceae occasionally attached to the body of males were identified, and the pollinic analysis of 68 females was carried out. One hundred twelve bees from 14 species were associated to 105 plant species which represented pollen, nectar, resin, and fragrances sources. These data reinforce the relevance of orchid bees to the maintenance and reproductive success of many tropical plants.