Introduction Bees are primary pollinators in most regions of the world (Bawa, 1990; Silberbauer-Gottsberger & Gottsberger, 1988). Their flight range strongly influences the sexual reproduction of most flowering plants and can further determine the genetic structure of plant populations (Campbell, 1985; Waser et al., 1996). The distance that bees travel in search of a resource can directly affect agricultural crops, given that bee pollination is necessary to generate 30% of the human food supply (Slaa et al., 2006). To increase the efficiency of collection and exploitation of good resources (Kerr, 1994; Contrera & Nieh, 2007), eusocial bees developed a sophisticated communication system that allows foragers to recruit other bees to profitable food sites (

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Pollen types found on the bodies of bees visiting Humiria balsamifera var. floribunda in a restinga area in Maranhão, Brazil. A -Humiria balsamifera (Humiriaceae), B -Byrsonima (Malpighiaceae), C -Chamaecrista ramosa (Fabaceae), D -Borreria (Rubiaceae), E -Chrysobalanus icaco (Chrysobalanaceae), F -Doliocarpus (Dilleniaceae), G -Ouratea (Ochnaceae), H -Cuphea tenella (Lythraceae), I -Mouriri guianensis (Melastomataceae), J -Stryphnodendron adstringens (Fabaceae), K -

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Euglossini bees are considered pollinators of a wide variety of plants in the Neotropical region, but little is known about their floral preferences. In this study, we identified the botanical species used as pollen and nectar sources by three Euglossa species (Euglossa cordata, Euglossa townsendi, and Euglossa securigera) using pollen residue found in brood cells from trap nests installed in an urban fragment in São Luís, Maranhão, Brazil. In 14 analyzed Eg. cordata nests, 23 pollen types were observed, in 7 Eg. townsendi nests, 10 pollen types were observed, and in 1 nest of Eg. securigera, 6 morph types were identified. Solanum (Solanaceae), Zanthoxylum (Rutaceae), Mimosa pudica (Fabaceae), and Chamaecrista (Fabaceae) pollen types were common to all three bee species. Principal components analysis showed 83.04% variability on the first two axes, demonstrating substantial similarity among the samples. Solanum, Mimosa pudica, and Zanthoxylum were the principal components in the ranking. Larger diversity values (mean = 0.80) in some samples indicate that the species gathered resources in a heterogeneous manner; this resembles the findings of other studies of Euglossa. In general, the bees exhibited overlapping niches with regard to the most abundant pollens in the nests, but the females showed individual plasticity when gathering the floral resources.