Nest construction and architecture of the Amazonian bumble bee (Hymenoptera: Apidae)

Abstract

The Amazonian bumble bee, Bombus transversalis, is mostly restricted to tropical rain forest of the Amazon Basin. Little is known of its biology, in part because its surface nests are cryptic and hard to find. Here we examine nest site characteristics, nest architecture and construction behavior from 16 colonies observed in different regions of Amazonia. We quantify structural features of the nest habitat and external and internal characteristics of the nests. We ascertain that nests are constructed on terra firme, on the surface of the ground and incorporate elements of growing vegetation as physical support. Nests consist of a thatched canopy of tightly woven leaves and rootlets, beneath which lies the brood and food storage pots. To build the nest, workers cut and transport leaves from the surrounding forest floor. Nests are dry inside, despite torrential rainfall and external relative humidity levels near 100%. Nests may be reused although a colony appears to persist for only one season.