Quoted: “Bees actually require the non-plant proteins of these pollen-borne symbionts to complete their growth and development — which makes them omnivores,” said Dr. Shawn Steffan, a research entomologist with the Vegetable Crops Research Unit of the Agricultural Research Service in Madison, Wisconsin and the Department of Entomology at the University of Wisconsin-Madison.
In the study, the Dr. Steffan and his colleagues from the University of Wisconsin-Madison, Cornell University and Hokkaido University used isotope- and gas chromatography-based methods to calculate the ratio of nitrogen in two types of amino acids (glutamic acid and phenylalanine) in the tissues of adult bees and in beebread.