That bees are essential to life on Earth we have known for some time. But now a new study has added a surprising piece to our understanding of their behaviour. In fact, a team of researchers has made an interesting discovery: pollinators do not choose the flowers from which to feed randomly, but do so following a precise nutritional logic. Just like an athlete who calibrates their diet according to the needs of the moment, wild bees and bumblebees also modulate their diet by combining protein, fat and carbohydrates according to the needs of the colony and the resources available in nature.
Specifically, research conducted by a team of experts from Northwestern University and the Chicago Botanic Garden observed eight species of wild bumblebees in the Rocky Mountains of Colorado for eight years. The goal was to accurately map the diet of these insects by analysing pollen collected and transported to the colonies. Once samples were taken from the different flowers visited by the bees and studied in the laboratory to determine their nutritional composition, the results were surprising.
Indeed, the analysis revealed that the macronutrient content of pollen varies greatly not only from flower to flower, but also throughout the seasons. Some pollens, for example, contain as little as 17 per cent protein, while others reach very high concentrations of up to 86 per cent. In general, spring flowers provide more protein-rich pollen, which is useful for sustaining the early and more energy-intensive phase of colonies, while towards the end of summer, pollens richer in fats and carbohydrates prevail, which are instead essential for survival in the run-up to winter.
According to Justin Bain, lead author of the study published in Proceedings of the Royal Society B: Biological Sciences, each type of pollen has its own “nutritional signature”: some can be compared, for example, to a steak, rich in protein; others to a light salad, with more fibre and sugar. In short, bees, far from being random visitors, know how to interpret this diversity and select flowers to compose a real food plan.
