-The nesting behavior of Centris (Hemisiella) vittata Lepeletier was studied in the Urbano Santos Cerrado in the northeast of Maranhão State, Brazil. To date, this species has only been studied in trap-nests. The nesting behavior of this species in a natural condition is recorded for the fi rst time. Nesting occurred in preexisting holes in dead trunks of aroeira, Astronium myracrodruon (Anacardiaceae), at the end of the rainy season. The cells were constructed with a mixture of sand and oil. After fi nishing the nests, females used only oil to line the entrance wall. Two females collected sand at the same time to build their nests, and another one was seen collecting resources at Byrsonima sp. (Malpighiaceae). The pollen load of one bee was analyzed and was found to contain mainly Hymenaea courbaril (Leg-Caesalpiniaceae). Development from egg to adult took about 60 days. Protandry was observed, being males smaller than females. The nests were parasitized by Coleoptera and Diptera. However, the females only showed aggressive behavior against females of the same species or genus. KEY WORDS: Solitary bee, nest, preexisting hole, bionomy Centridini bees are solitary, medium to large sized species which use different kinds of nesting substrata. The tribe includes species that excavate simple or compound nests in fl at ground or in vertical banks (Vinson & Frankin 1988, Batra & Schuster 1977, Rozen & Buchmann 1990, Aguiar & Gaglianone 2003. Other species build their nests in holes of wood, such as tree trunks, inside termitaria or use preexisting cavities, such as cells abandoned by wasps or other bees (Coville et al 1983, Silva et al 2001, Aguiar et al 2006, Ramos et al 2007a, old beetle boring (Michener & Lange 1958) and trap-nests (Garófalo et al 1989, Pereira et al 1999, Aguiar & Garófalo 2004, Mendes & Rêgo 2007.These bees are considered effective pollinators for a variety of plant species, particularly "oil plants" such as Malpighiaceae, Krameriaceae and Scrophulariaceae (Vogel 1974, Neff & Simpson 1981, Buchmann 1987, Rêgo & Albuquerque 1989.Due to the essential ecological role played by these bees in a wide range of fl oral communities, studies of the biology of these species are important for conservational efforts to be developed for solitary bees and the plant species they pollinate. The aim of this study was to provide data on the nesting behavior of Centris vittata Lepeletier, a species distributed in several Brazilian ecosystems.
Material and MethodsThe study was carried out in an area predominated by Cerrado fragments in the municipality of Urbano Santos (3º12'28'' S, 43º24'12'' W), northeast of Maranhão State, in Santo Amaro farm, owned by Comercial & Agrícola Paineiras, about 500 km from São Luís. The main soil types are sandy (well drained and with low natural fertility), quartz sand and red-yellow latosol. The dominant vegetation is that typically found in the Cerrado, although seasonal semideciduous forests and patches of mixed vegetation may also be found (Brasil 1984). The area, where ...