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Stingless bees (Meliponini) are expected to play a central role in structuring mutualistic networks in the Neotropics, as they are generalist and often abundant pollinators. Living in populous social colonies with a perennial life cycle, they require continuous large amounts of resources and often forage on abundant flowerings such as mass‐flowering throughout the year.In this field research, we seek to understand how temporal variations on foraging activity of stingless bees and abundance of mass‐flowering partner plants affect the topology of the plant–pollinator mutualistic networks. The networks were compared between spring and summer, periods of high and low abundances of flowerings and mass‐flowering, respectively.Bees were sampled on flowers, in replicates of floodplain fields in Atlantic Forest of southern Brazil. Interactions with partner plants were considered effective only when bees had pollen on their bodies (potential pollinators). Through analysis of pollen grains attached to their bodies, several topological metrics of networks and functional categories were obtained. The robustness or networks resistance to secondary species loss due to simulated focal species extinction was also measured.The networks maintained similar general structure throughout the year (high nestedness, moderate modularity and connectance, low community‐level specialisation and negative dependency asymmetry). Particularly, nestedness and dependency asymmetry did not change between the two seasons. Community‐level specialisation was higher in summer, contrary to expectations, when there was a collapse in the supply of floral resources and also a reduction in the abundance and foraging pressure of stingless bees. As there was also a greater number of specialist pollinators in summer, the hypothesis of temporal displacement due to foraging pressure from generalists was proposed. At the same time, stingless bees oscillated between network hubs in spring and connectors in summer, reflecting the variation in their abundance between these two seasons. In spring, the greater concentration of foraging by these generalists in the abundant mass‐flowering probably attenuated their diffuse competitive pressure on all other pollinators, even though the foraging overlap was higher in this period. In this period of high abundance of floral resources, specialist pollinators capable of expanding the realised niche are active.Based on recent theoretical conclusions of dynamic model of mutualistic networks structure that incorporated effects of inter‐specific competition and adaptive foraging, we argue that the adaptive foraging of generalist and abundant stingless bees contributes in an important way to the high nestedness and robustness of networks, which ultimately favour the coexistence of species in the long term. Particularly, taking the high intra‐annual turnover of bee and plant species between the two seasons, and the similar floral constancy of both generalist stingless bees and specialist pollinators, we also infer that stingless bees act as generalised pollinators in the networks rewiring throughout the year. [ABSTRACT FROM AUTHOR]

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We describe the nesting biology of Centris (Paracentris) burgdorfi, a solitary bee that nests in sandstone in northeastern Brazil. The nest consists of a shallow tunnel with access to the brood cells. Females of C. burgdorfi made 1–7 brood cells per nest with each cell requiring 2.58 ± 0.40 ( X ¯ ± SD) days to construct. The average cell-building construction time was longer when compared to other Centris species. Females were larger than males, and this difference was reflected in the size of their respective emergence cells. The temperature within C. burgdorfi nests was lower when compared to ambient temperature. Our study is the first to report the nesting biology of C. burgdorfi. The detailed behavior of the female inside the nest was also described, which is unusual in the study of solitary bee nesting biology. [ABSTRACT FROM AUTHOR]

The article discusses a study that investigated plants used by the Centris tarsata bee species for its larval food supply in southern Brazil and determined if the bee is polylectic or oligolectic in the region. The study was conducted from March 2002 to December 2003 in the Parque Municipal das Araucárias, Guarapuava (PR) in southern Brazil. It was found that the Solanaceae plant family was visited most often, and that two members of the family were the primary pollen sources for the bees in the study area. The selective behavior of females of the bee species suggests that the bees are oligolectic in their larval provisioning.

Sterols are essential molecules in the membrane lipid composition and precursors of important sterol hormones that regulate many developmental processes. Insects are unable to synthesize sterols de novo and, thus, all phytophagous insects depend on an exogenous source of sterols for growth, development, and reproduction. The sterol requirements of social bees are not fully known due to the fact that there is no well-defined diet available throughout the year with regard to floral resources. Our study aimed to characterize the sterols present in pollen stored in Melipona marginata and Melipona scutellaris colonies, as well as evaluating their presence in the mandibular, hypopharyngeal, and cephalic salivary gland secretions. We analyzed the chemical composition of pollen stored in the colonies and the composition of the cephalic glands of workers in three adult functional phases (newly emerged, nurses, and foragers) by gas chromatography and mass spectrometry. The results showed that the pollen analyzed contained campesterol, stigmasterol, sitosterol, isofucosterol, lanosterol, and small amounts of cholesterol. The glands showed the same compounds found in the pollen analyzed, except lanosterol that was not found in M. scutellaris glands. Surprisingly, cholesterol was found in some glands with relative ratios greater than those found in pollen. [ABSTRACT FROM AUTHOR]

Aiming at promoting interaction among researchers and the integration of data from their pollen collections, herbaria and bee collections, RCPol was created in 2013. In order to structure RCPol work, researchers and collaborators have organized information on Palynology and trophic interactions between bees and plants. During the project development, different computing tools were developed and provided on RCPol website (http://rcpol.org.br), including: interactive keys with multiple inputs for species identification (http://chaves.rcpol.org.br); a glossary of palinology related terms (http://chaves.rcpol.org.br/profile/glossary/eco); a plant-bee interactions database (http://chaves.rcpol.org.br/interactions); and a data quality tool (http://chaves.rcpol.org.br/admin/data-quality). Those tools were developed in partnership with researchers and collaborators from Escola Politécnica (USP) and other Brazilian and foreign institutions that act on palynology, floral biology, pollination, plant taxonomy, ecology, and trophic interactions. The interactive keys are organized in four branches: palynoecology, paleopalynology, palynotaxonomy and spores. These information are collaboratively digitized and managed using standardized Google Spreadsheets. All the information are assessed by a data quality assurance tool (based on the conceptual framework of TDWG Biodiversity Data Quality Interest Group Veiga et al. 2017) and curated by palynology experts. In total, it has published 1,774 specimens records, 1,488 species records (automatically generated by merging specimens records with the same scientific name), 656 interactions records, 370 glossary terms records and 15 institutions records, all of them translated from the original language (usually Portuguese or English) to Portuguese, English and Spanish. During the project's first three years, 106 partners, among researchers and collaborators from 28 institutions from Brazil and abroad, actively participated on the project. An important part of the project's activities involved training researchers and students on palynology, data digitization and on the use of the system. Until now six training courses have reached 192 people. [ABSTRACT FROM AUTHOR]