ABS 2022
Picky Eaters: Generalist Bees Sample Pollen on Flowers by Ingestion Before Collection
Jenny K. Burrow1, Jacob S. Francis2, Faith E. Dall1, Michelle Bowe1, Anne Leonard3, Avery L. Russell1, Maggie M. Mayberry1. 1Department of Biology, Missouri State University, Springfield, Missouri, United States; 2Department of Entomology and Nematology, University of California, Davis, Davis, California, United States; 3Department of Biology, University of Nevada, Reno, Reno, Nevada, United States

Determining how animals assess food quality is fundamental to understanding foraging behavior. Generalist bees collect floral nectar and pollen, and the quality of these two foods is highly variable among plant species. Given often strong nectar and pollen preferences, bees likely assess the quality of both foods. Yet while bees assess nectar quality while ingesting it, pollen is stored externally in pollen-baskets. We investigated how bumblebees might assess pollen quality, predicting they might assess quality by ingesting small amounts while foraging. We collected foragers from the field and quantified pollen species diversity and abundance in the pollen-baskets and gut. Field results in combination with a controlled lab assay established that foragers consume pollen directly from flowers. We also found that pollen foragers were more likely to have pollen in their crops than nectar foragers and that pollen diversity was greater for pollen foragers. Our results implicate ingestion and potentially gustatory cues as mechanisms used by generalist bees to assess pollen quality, suggesting that pollen and nectar are assessed similarly, even though stored very differently.