Understanding pollen specialization in mason bees: a case study of six species
- PDF / 1,482,412 Bytes
- 16 Pages / 595.276 x 790.866 pts Page_size
- 119 Downloads / 180 Views
HIGHLIGHTED STUDENT RESEARCH
Understanding pollen specialization in mason bees: a case study of six species Megan K. McAulay1,2 · Saff Z. Killingsworth2 · Jessica R. K. Forrest1,2 Received: 2 January 2020 / Accepted: 10 October 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Many bee species are dietary specialists and restrict their pollen foraging to a subset of the available flowers. However, the reasons for specialization—and the reasons certain plant taxa support numerous specialists—are often unclear. Many bees specialize on the plant family Asteraceae, despite evidence its pollen is a poor food for non-specialists. Here, we studied six mason bee (Osmia) species, including three Asteraceae specialists, to test whether observed pollen-usage patterns reflect larval nutritional requirements, to investigate what aspects of Asteraceae pollen make it unsuitable for non-specialists, and to understand how Asteraceae specialists tolerate their seemingly low-quality diet. We reared larval bees on host and nonhost pollen and found that Asteraceae specialists could develop on nonhost provisions, but that other bees could not survive on Asteraceae provisions. These effects did not seem related to nutritional deficiencies, since Asteraceae provisions were not amino acid deficient, and we found no consistent differences in digestive efficiency among pollen types. However, Asteraceae specialists completed more foraging flights per larva, generally collected relatively larger provisions, and produced more frass (waste) than the other species, suggesting quantitative compensation for low food quality. Toxins, deficiencies in unmeasured nutrients, or aspects of pollen grain structure might explain poor survival of non-specialists on Asteraceae provisions. Our results suggest that floral host selection by specialist bees is not related to optimizing larval nutrition. We recommend further investigation of host-selection behaviour in adult bees and of pollen digestion in larvae to better understand the evolution of bee–flower associations. Keywords Amino acids · Nutrition · Oligolecty · Osmia (Megachilidae) · Asteraceae
Introduction
Communicated by Roland A. Brandl. Our study goes beyond past studies of pollen specialization in bees by examining mechanisms underlying bee survival on different pollens and by studying foraging behaviour of the bees in the field. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00442-020-04786-7) contains supplementary material, which is available to authorized users. * Megan K. McAulay [email protected] 1
Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON K1N 6N5, Canada
Rocky Mountain Biological Laboratory, Crested Butte, CO 81224, USA
2
Biologists have long wondered why some species specialize on a subset of the available resources while others are generalists (Darwin 1859; Futuyma and Moreno 1988; Simon and Toft 1991; Eby 1998; Forister et al. 2012; Hardy et al. 2020). For example
Data Loading...
