Nutrients for Bees

The nutrients a bee needs are carbohydrates for energy, protein and amino acids for growth and brood rearing, fats and sterols, vitamins, minerals and water. The honey bee gets almost all of these from two natural sources: carbohydrates from nectar and honey, and everything else from pollen. This page explains what each nutrient does, where it comes from in nature, and which needs feeding can and cannot meet.

What do honey bees eat?

The food system of a honey bee colony rests on two pillars:

• Nectar and honey: Consist almost entirely of sugar and water. They are the colony's energy source.
• Pollen: The only natural source of protein, amino acids, fats, sterols, vitamins and minerals. Bees pack pollen into cells and mix it with honey and secretions, storing it as bee bread (perga).

In addition, water is a vital requirement for the bee. Over a year a colony collects tens of kilograms of pollen and much more nectar than that. The diversity of these foods matters as much as their quantity: pollen from different plants provides more balanced nutrition than pollen from a single source.

Carbohydrates: the bee's fuel

Carbohydrates are the fuel for the flight muscles, for the shivering that heats the cluster in winter and for wax production. The main sugars in nectar are sucrose, glucose and fructose. While processing nectar, bees use the enzymes they secrete to split sucrose into glucose and fructose, evaporate the water and turn it into honey.

Not every sugar is suitable for bees. Lactose, galactose, mannose and some plant sugars cannot be used by bees; some are toxic. That is why only white sugar (sucrose) or glucose–fructose syrups made for bees are used as bee feed; milk powder, brown sugar, molasses and grape molasses are not suitable.

• Honeydew honey and winter: Some honeydew honeys (pine, oak, etc.) and high-mineral honeys can cause more waste to build up in the bees' gut over winter. In long, cold winters this can contribute to defecation inside the hive (signs of dysentery).
• Honey that sets in the comb: Some honeydew honeys high in melezitose harden in the comb; bees find this honey hard to use in winter.

Protein and amino acids: the building blocks of brood

Protein is needed for larval growth, for the development of the glands of young nurse bees and for royal jelly production. The bee's only natural protein source is pollen. The protein in pollen is broken down into amino acids in the bee's body and used.

There are 10 essential amino acids that the honey bee cannot make itself and must obtain from food: arginine, histidine, lysine, tryptophan, phenylalanine, methionine, threonine, leucine, isoleucine and valine. The value of a pollen depends not only on its total protein content but also on whether it contains enough of these amino acids.

• The protein content of pollen varies greatly by plant: Some plants' pollen is rich in protein, others' is poor.
• A single source is risky: In large monoculture areas or in dearth periods, bees may be left dependent on the pollen of only one or two plants; this can adversely affect brood rearing and the bees' lifespan.
• Who eats it: Most of the pollen is consumed by young nurse bees; the larvae are fed on the food they secrete. Foragers, on the other hand, live mainly on carbohydrates.

Fats and sterols

Pollen is the bee's source of fat and fatty acids. As well as being an energy store, fats form part of cell membranes and some hormones. Bees can live for a long time thanks to their fat body, which is especially well developed in winter bees.

Sterols are particularly important: the honey bee cannot make sterols itself and gets them entirely from pollen. 24-methylenecholesterol, the most abundant sterol in bee tissues, is passed to the larvae via the nurse bees. This is one of the reasons why pollen substitutes cannot be as successful as natural pollen.

Vitamins and minerals

The best-known vitamin requirement for bees is the B vitamins; these are needed for producing larval food and for brood development, and they come naturally from pollen. The role of other vitamins in bee nutrition has been less researched. Evidence for the benefit of giving bees additional vitamin supplements is limited; details are on the Nutritional Supplements and Vitamins page.

Minerals (potassium, phosphorus, magnesium, calcium, iron, zinc, etc.) also come mainly from pollen, and partly from water. The most abundant mineral in pollen is potassium. The mineral requirement is small, but an excess is also harmful: high-mineral feeds and salty water can cause digestive problems, especially in winter.

Water: the forgotten nutrient

Water is needed to dilute honey, prepare larval food, cool the hive and dissolve the sugar in fondant. On hot days a significant proportion of foragers carry nothing but water. If there is no clean water near the apiary, setting up a water point stops the colony going to distant and dirty sources for water.

Functions and sources of nutrients

Nutrient	Natural source	Main function	If deficient
Carbohydrate	Nectar, honey	Energy, heating, wax production	Starvation, winter losses
Protein / amino acids	Pollen, bee bread	Brood, royal jelly, glands	Less brood, shorter bee lifespan
Fats and sterols	Pollen	Cell structure, hormones, fat body	Brood development weakens
Vitamins	Pollen	Larval food, metabolism	Brood development may be affected
Minerals	Pollen, water	Body functions	Effect little researched; excess harmful
Water	Natural sources, water point	Cooling, dilution, larval food	Brood care suffers

Nutritional needs by life stage

• Larvae: Fed on food secreted by nurse bees. Queen larvae are fed only royal jelly; worker larvae receive food with added honey and pollen in later days.
• Young nurse bees: The group in the colony that consumes the most pollen; without protein they cannot produce royal jelly.
• Foragers: Live mainly on honey and nectar, that is, on carbohydrates.
• Winter bees: Emerge in autumn from well-fed larvae; they carry larger reserves of fat and protein in their bodies, which is why they can live for months.
• Queen: Fed throughout her life on royal jelly secreted by the workers; her laying rate depends on the food the colony can provide her.

Which nutrients does feeding provide?

The feeds a beekeeper gives replace only part of the natural foods:

• Syrup and fondant provide only carbohydrates; they contain no protein, fat, vitamins or minerals.
• Pollen substitute provides protein but cannot fully replace natural pollen in terms of amino acid balance, sterols and vitamins.
• Natural pollen or frames of bee bread are the most complete protein source; but they should be taken only from healthy colonies and from your own apiary.

So the best nutrition strategy is to set up the apiary in a place with varied flower sources throughout the year and to use feeding only as a supplement in periods when nature is not enough. Which feed to give in which situation is explained on the Feeding: Syrup, Fondant and Pollen page.