Different bees have different diets at the same buffet

Photo Credit

Forest Service photo by Anthony D. Vaudo

Study site and bees represented in this study. Left: The meadow at Lake Van Norden, CA. Middle top: Bombus (Pyrobombus) vosnesenskii; top right: Osmia (Melanosmia) sp.; bottom right: Melissodes (Eumelissodes) sp.; middle bottom: Calliopsis (Nomadopsis) edwardsii.

Pollen provides bees with their main source of protein and fats, but pollen nutritional quality can vary between plant species. Likewise, different bee taxa may have different nutritional needs which can influence the plants they collect pollen from.

In a new study, researchers looked at the foraging behavior and pollen collection of the most abundant bee taxa (including bumble bees, long-horned bees, mining bees, and mason bees) in a subalpine meadow of the Sierra Nevada mountain range over three years.

The taxa found at the study site collected nutritionally distinct pollen loads, had different nutritional needs, and adjusted their foraging behavior accordingly to favor the same co-flowering plant community.

Bumble bee species that collected similar pollen nutrition foraged flexibly among their preferred host plants each year, potentially to relieve competition for pollen resources. These findings support the design of restoration and revegetation plant lists to include considerations for pollen nutritional diversity to better support the needs of a diverse pollinator community and their pollination services.

This is one of the only studies that directly analyzes the nutritional value of pollen collected by wild bee communities and supports the concept that wildflower communities that offer a diverse array of nutrients in their floral rewards (pollen and nectar) are important for supporting wild pollinators.

This is also one of the first studies to show that different wild bee taxa have different nutritional needs in field settings. These findings will help us understand the foraging preferences and pollination services offered by wild bee communities, which are important for stable ecosystems, agricultural productivity, and the design of restoration plant lists.