Seasonal variation in nutritional preference in a ground nesting bee

All insects must balance the acquisition of different nutrients while foraging to achieve a nutritional target. In the case of bees, females tend to reach taxon-specific targets by balancing the macronutrient mixture of proteins and lipids across pollens they collect. However, recent findings suggest that preferences for different nutrients (i.e., nutritional preference) may shift though time, especially for bees that forage amid continuous phenological turnover of floral species. Shifts in nutritional preference over time may indicate a flexible nutritional target, rather than a fixed one, allowing the persistence of bee species. To test the hypothesis that nutritional preferences shift over time, we sampled pollen loads of Halictus ligatus, a widespread generalist with an extended foraging season. Individuals were sampled weekly from March-September in 2024 at an experimental garden comprised of native forbs. We quantified pollen availability weekly among all plants and compared it with the relative composition of plant species in collected pollen loads. Preliminary data reveal that H. ligatus foraging choices diverge significantly from resource availability across seasons, suggesting possible shifts in nutritional preference. Ongoing work explores whether these choices reflect preferences for plant species with unique protein-to-lipid ratios by measuring the macronutrient composition of pollen loads and floral resources at the study site through time.