Figure 3.

Summary of mechanisms driving social bee fitness and thus colony population growth as revealed by our study. High plant species richness in a habitat (dark green) ensures continuous availability and increases overall (nutritional) quality of available resources (light green). Continuous resource availability increases foraging activity and thus resource intake by bees resulting in an increased quantity and nutritional quality of stored food (dark yellow). Increased quantity of food stores enhances colony fitness and reproduction (i.e. brood volume, queen- and worker production), resulting in larger populations. In biodiverse environments, resource quality does not limit bee fitness.