How do bees balance the nutrient content of pollen for their larvae?

The underlying causes of the global decline of wild bees is important to understand because bees are essential for pollination of both crops and wild plants (Potts et al. 2016). Bees forage on nectar and pollen, where the latter is the main resource used to feed the growing larvae (Lau et al. 2022). Many bees, either at species or individual level, show clear preferences for pollen from certain plant species or genera: at the species level for solitary bees (Persson et al. 2018; Yourstone et al. 2021;2023). It has been suggested that this is caused by an inability by the larvae to digest pollen from certain plant genera, likely because of their chemical protection (Praz et al. 2008; Sedivy et al. 2012). However, it may also be caused by the need to optimise the nutritional balance between macronutrients, i.e., carbohydrates, proteins, and lipids (Leonhardt et al. 2022), and a recent study has shown that the availability of specific macronutrients, rather than flower species per se, shape plant-pollinator networks in real landscapes (Vaudo et al. 2024).

Potential aims

In this project you will look closer into if and how bee species, such as Osmia bicornis (Red mason bee) and Bombus terrestris (Buff-taled bumblebee) optimise nutritional content of its pollen collection over time, and if this is restricted by the quality of the floral resources in the surrounding farmland landscape.

Methods and time plan

You will use existing data on pollen foraging collected by Persson et al. (2018) and Yourstone et al. (2021; 2023), combined with published data on pollen nutritional content (e.g. Hanley et al 2008; Pamminger et al 2019). Depending on your interests and the extent of the project you may also using image analysis to extract you own pollen data already collected from bees (Olsson et al. 2022), and, or make pollen collection in the field during summer and perform nutrient assessments in the lab.

Project duration: 15-30 credits using existing data only, 45-60 credits including field data collection/lab work