Nesting biology of Tetrapedia amplitarsis (Hymenoptera: Apidae: Tetrapediini)

Tetrapedia amplitarsis is an oil-collecting solitary bee that nests in pre-existing cavities and differs from the other species of the genus in several biological aspects, as nest architecture and phenology. The aim of this study is to present detailed information on its nesting biology. Monthly field sampling was conducted from December 2011 to November 2013 using trap-nests in the Serra do Japi, Jundiaí, São Paulo, Brazil. Thirty nests were sampled, in which 168 brood cells were built. The nests consisted of molded cells in urn shape, made with a mixture of sandy material and floral oil, in linear series with horizontal orientation. Completed nests had one to 14 brood cells. Most nesting activities occurred in the hot/wet season, and the offspring emerged in the cold/dry season. The offspring time development ranged from 24 to 316 days, suggesting a univoltine life cycle but with the possibility of the occurrence of a second generation. The sex ratio was significantly female-biased (2.62♀:1♂). Unknown causes and fratricide were the main factors of mortality. Dermestes sp, microlepidoptera, and Anthrax oedipus were the natural enemies associated with the nests. Our results highlight a different Tetrapedia bee, for which many biological aspects are yet to be studied.