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Access to abundant and diverse floral plant sources is essential for generalist bees as they obtain all energy and nutrients required from pollen and nectar. Despite their importance, we still know little about the precise nutritional requirements of most bee species. Here, we investigated differences in floral and amino acid profiles of pollen collected by five bumblebee species in southern Germany, which had access to the same spectrum of plant species and thus sources of nutrition. We found that different bumblebee species visited different floral spectra for pollen collection but nevertheless had highly similar pollen amino acid profiles. This finding suggests that common bumblebee species only slightly differ in their nutritional target for amino acids in pollen. In fact, floral and chemical composition of pollen loads appear to be largely determined by the plant community present at a site as bumblebees attempt to maximize site-specific nutrient collection efficiency. [ABSTRACT FROM AUTHOR]