Fig. 1. Comparison of: a. protein and; b. sugar content of brood food of young (1-3 d) and old (4-6 d) worker larvae (Data summarized from Kunert and Crailsheim, 1987) and laboratory diet, both percentages of dry weight. Protein decrease and sugar increase are due to the increase in sugar added to diets (Aupinel et al., 2005). Range of content is determined by variation in royal jelly protein (Sabatini et al., 2009) and sugar (Brouwers, 1984) content. Protein and sugar in yeast were excluded from calculations.