Pollen columns and a wax canopy in a first nest description of Bombus (Cullumanobombus) morrisoni (Apidae)

Abstract

In this study, we describe the first reported nest of Bombus morrisoni, a species with an extensive range in the arid Intermountain Region of the Nearctic. The mature, naturally terminated nest consisted of 424 nest cells (cocoons), with 328 non-gyne cells and 94 gyne cells. The nest also had two kinds of understudied structures associated with bumble bee nests: pollen columns and a wax canopy. We found five pollen columns rising amid the cocoons. A 0.3-mm-thick wax canopy spanned over the entire nest. An estimated 40 million pollen grains were incorporated into the 19 g wax canopy, demonstrating that B. morrisoni devotes a significant amount of pollen to this non-dietary purpose. Bombus morrisoni is a species of conservation concern due to an observed reduction in their historic distribution. The data generated in our study contributes to the much-needed comparative accounts of bumble bee nesting biology and has consequential implications in supporting management and conservation decisions.