Pollen preference of two Andrenid bees in British Columbia’s oak-savannah ecosystem

Julie Wray, Elizabeth Elle

Abstract


Although understanding the dietary requirements of species is an essential component of their conservation, the extent of specialisation is unknown for most pollinators in Canada. In this paper we investigate pollen preference of two bees, Andrena angustitarsata Vierick [Hymenoptera: Andrenidae] and A. auricoma Smith.  Both species range widely throughout Western North America and associated floral records are diverse.  However, these species were primarily associated with spring-blooming Apiaceae in the oak-savannah ecosystem of Vancouver Island, BC, specifically Lomatium utriculatum [Nutt. ex Torr. & A. Gray] J.M. Coult. & Rose, L. nudicaule [Pursh] J.M. Coult. & Rose, and Sanicula crassicaulis Poepp ex. DC. Floral records and scopal pollen composition from two regions on Vancouver Island indicate specialisation in oak-savannah habitats where Apiaceae are present. Both species were also caught in low abundances in residential gardens where Apiaceae were scarce, and our results indicate they were foraging on unrelated plants with easily accessible nectar and pollen rewards. Further study of these species is needed to understand whether preferences observed locally in BC exist elsewhere in their range. Our findings contribute to understanding pollen preference in natural and urban areas, and highlight two bee species to consider for conservation action in a highly sensitive fragmented ecosystem.


Keywords


Andrenidae; Apidae; oligolecty; pollen preference

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References


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