Nesting ecology of the oil-collecting bee Centris (Melacentris) conspersa Mocsáry and its potential association with the cleptoparasite Cyphomelissa diabolica Friese (Apidae: Centridini, Ericrocidini)

Abstract

The genus Centris is by far the most diverse group of oil-collecting bees worldwide. In spite of its broad distributional range through Americas, data on the biology of several species remain unknown. We aimed to study the nesting ecology of Centris (Melacentris) conspersa in two islands in the Atlantic Forest domain, Southeastern Brazil. In both areas, nests were constructed in sloping, shaded areas of clayey soil. Two specimens emerged around one year after the brood cells were collected at the nesting site, indicating that this species is likely to be univoltine. Four females of the cuckoo bee Cyphomelissa diabolica were recorded flying over nest entrances of C. conspersa, what may be the first putative host record for this cleptoparasitic genus. Also, the mutillid Hoplomutilla spinosa was also registered at the nest aggregation. The pollen analysis of the residual content of 32 brood cells revealed a narrow spectrum of plants visited, with only six pollen types from five botanical families. Stigmaphyllon arenicola (Malpighiaceae) was the lone floral oil source identified, and Senna multijuga (Fabaceae) pollen grains were found dominant (63.5 to 100%) in all samples analyzed. Despite occurring in a plant species-rich biome as the Atlantic Forest, C. conspersa can be classified as an oligolectic bee species concerning both pollen and oil collection.