Nesting activity of Centris aenea Lepeletier, 1841 was studied in two Brazilian habitats, Caatinga (Monte Santo, Bahia) and Cerrado (Palmeiras, Bahia and Luiz Antônio, São Paulo). Nests were excavated in the ground and did not tend to be aggregated together at the two sites, but at Palmeiras, nests were in a large aggregation. Nest architecture consists of a single unbranched tunnel, sloping to vertical, which leads to a linear series of four cells, placed from 8 to 26 cm in depth. Cells are urn-shaped with a rounded base, and their cell caps have a central hollow process, as in other Centridini. Nest architecture of C. aenea was compared to other species of Centris Fabricius, 1804. Provisions are composed of a pollen mass covered by a thin liquid layer on which the egg is placed. Females were observed gathering oil on Mcvaughia bahiana W.R. Anderson flowers from October to March in the Caatinga, and on Byrsonima intermedia A.Juss. as well as other Malpighiaceae species from August to December in the Cerrado. Pollen is gathered by buzzing flowers of Solanaceae, Caesalpiniaceae, Malpighiaceae, and Ochnaceae. Several nectar sources were recorded. There is indirect evidence that Mesoplia sp. parasitizes nests of C. aenea in the Cerrado.

This study was designed to identify important food resource plants used by bee species in a Caatinga area, as well as describe the local patterns of floral use by bees. A total of 1,145 foraging bees, belonging to 60 species, were captured while visiting 50 plant species. Melochia tomentosa L., Sida galheirensis Ulbr., Erythroxylon catingae P. Cowan, and Ziziphus cotinifolia Reiss. were the most frequently visited plants. Melochia tomentosa, Solanum paniculatum L. and S. galheirensis were visited by larger number of bee species. Some oligolectic bees were identified. Apis mellifera Linnaeus, 1758 and Trigona spinipes (Fabricius, 1793) had the largest trophic niche breadth (2.71 and 2.31). The trophic niche overlap was highest (0.52) between Xylocopa grisescens Lepeletier, 1841 and Frieseomelitta silvestrii (Friese, 1902). The low trophic niche overlap between Apis mellifera and native stingless bees seems to be the result of intensive exploration of only a few flower sources by Africanized bees, not frequently visited by meliponids.