The known unknowns of wild bee nutritional ecology and conservation

Pollen nutritional quality is a crucial component of bee health and has emerged as a primary factor that can promote resilience to disease, pesticides, and climate change. Much of this foundational work has reasonably focused on tractable model bee species such as honey bees (Apis mellifera) and bumble bees (Bombus spp.). Yet, many basic questions remain about how pollen as a nutritional resource structures interactions among diverse communities of bees and plants in working lands. For example, understanding how co-flowering plant species within a focal community vary in pollen macronutrient content is a critical step for charting baseline conditions and informing restoration efforts. Likewise, we know almost nothing about the scale or potential drivers (e.g. genetic variation, phenotypic plasticity) of population-level variation in pollen nutritional traits that are likely relevant to the performance of wild bees. Here, we 1) summarize our recent efforts to understand how pollen protein and lipid content may structure interactions between wild bees and flowers in Great Basin/Sierra Nevada communities; and present new data on 2) the scale of geographic and potential climactic drivers of variation in pollen nutritional content among 35 species of wildflowers, and 3) new techniques in nutritional analytical chemistry to characterize variation in pollen traits. These data and perspectives on the field of bee nutritional ecology are pertinent for addressing pollinator conservation ecology in a changing world.