Bees rely on two distinct floral resources, nectar and pollen, for the complete nutrition necessary for the survival and function of their colony. Nectar serves as the primary source of carbohydrates, fueling the energy needs of adult bees for all their strenuous activities. Pollen is the sole natural source of protein, fats, and micronutrients, making it indispensable for the growth and development of young bees and the overall health of the hive. Both substances are collected by forager bees, processed, and stored within the hive as honey and beebread, which are the stable food reserves.
Nectar: The Primary Fuel Source
Nectar is a sugary liquid produced by plant glands called nectaries, and it is the bee’s main carbohydrate source, equivalent to their immediate energy supply. The raw liquid collected from flowers is mostly water, with a sugar concentration that often ranges from 25% to 55%. The sugars within nectar are primarily sucrose, glucose, and fructose. The ratio of these three varies greatly depending on the plant species.
This carbohydrate-rich liquid powers the high metabolic demands of adult worker bees. The sugars provide the energy required for all physical activity, particularly the intense muscular work of flying and foraging. Nectar also supplies the energy for essential hive functions, such as heat production to regulate the colony temperature and the secretion of beeswax for comb construction. Trace amounts of amino acids, minerals, and vitamins are also present.
Pollen: Essential for Growth and Development
Pollen is the reproductive dust of plants, and for bees, it is the fundamental source of protein and other macronutrients. Its composition includes crude protein, which can vary significantly from 6% to over 30% of dry weight, along with lipids, vitamins, and minerals. The protein is made up of amino acids, ten of which are considered essential for honey bees. A varied diet of pollen from different plants is necessary to ensure all these amino acids are obtained.
This high-protein diet is critical for the growth of larvae and the physiological development of newly emerged nurse bees. Young worker bees consume large amounts of pollen to develop the hypopharyngeal glands, which are necessary to produce the brood food, including royal jelly. The protein and lipid content in pollen directly influences the health and longevity of the queen and the workers. A single worker larva requires an estimated 124 to 145 milligrams of pollen to reach maturity.
From Flower to Hive: Processing the Harvest
The raw materials collected by forager bees must be chemically and physically transformed into stable, long-term food stores once they return to the hive. Nectar is converted into honey through enzyme action and dehydration. When the forager bee collects nectar, it stores the liquid in its honey stomach and adds enzymes, such as invertase. These enzymes begin to break down the complex sugar sucrose into the simpler sugars, glucose and fructose. House bees then repeatedly pass the nectar, adding more enzymes, and deposit the partially processed liquid into open honeycomb cells.
The bees then vigorously fan the cells with their wings to evaporate the excess water content, reducing it from around 80% down to 13% to 18%. This low moisture content and the presence of natural preservatives, like gluconic acid and hydrogen peroxide, prevent fermentation. This process creates honey, a dense, stable food source.
Converting Pollen to Beebread
Pollen is converted into beebread, a more digestible and storable form, by house bees in the comb cells. The pollen pellets brought in by foragers are packed tightly into the cells, with workers using their heads to tamp down the material. Nectar, honey, and saliva containing enzymes are added to the packed pollen. This mixture then undergoes a natural fermentation process, primarily driven by lactic acid bacteria. Fermentation increases the acidity, which preserves the beebread and breaks down the tough outer coating of the pollen grains, making nutrients more accessible.