Eating Well

It’s been said ‘an army marches on its stomach’ and any beekeeper worth their salt knows that their honey bees’ diet (including ‘salt’!) is essential to their output, in peace and war. As yet we haven’t been able to fully replicate a complete, naturally-foraged diet with supplementary alternatives. Could that soon change?

By Dave Black

Surely it’s more than a little surprising that, among all the animals we have tamed or caged, apparently honey bees are the only ones that have to be left free to gather their own food. Almost anything in a zoo can remain penned. People keep aquariums of exotic tropical fish at home for years and years. Dogs, horses, sheep, snakes and hamsters can all be housed and fed to live out their lives contentedly into old age, but honey bees can’t manage more than a few summer weeks in containment, ultimately because we don’t know enough about what they eat.

It’s hard to beat the real stuff. A honey bee seeks out dandelion pollen and nectar. Photo: Peter Bray.

Nutrition

Nutrients are substances that an organism must obtain from its surroundings to grow and stay alive, and when it comes to honey bees we don’t know what all these substances are. It’s obvious they harvest nectar, pollen, and water, but there are some details about the nutrients contained in these resources which we have been missing. We can supplement their natural diet (for a little while), but we’ve never managed to substitute an artificial replacement, and planting supplemental forage crops can turn out to be a bit ‘hit and miss’.

Part of the reason this is complicated is that these particular bees live as a colony of dissimilar individuals, and not as a herd of similar ones. Generally honey bees move from a protein-rich diet to a carbohydrate-rich diet as they age. An individual larva’s nutritional needs are different from an adult’s; a drone’s requirement different from a queen’s, or a nurse bee, or a forager.  As the colony as a whole responds to change in its environment, and the size of the proportions of individuals in it shift, the dietary needs of the colony must adjust to an eccentric availability of food resources. If you’re feeding them, what they need in September isn’t necessarily the same as what they need in March. But it’s more than that.

Healthy eating

Honey bees (not so all bees) have adapted to feed on a plant-based diet of floral nectar and pollen. Nectar and honey dew are the natural sources of carbohydrates for honey bees. An adult worker bee uses the equivalent of about 11mg of dry sugar a day.[i] Nectars contain varying proportions of sucrose and its component monosaccharides, glucose and fructose. There are other things in nectar; different sugars, some proteins, minerals, and various phytochemicals. While they can be essential for other animals, they are not thought to be important to honey bees.

Pollen provides the bees with protein and, as a nurse, a bee would consume in the order of 6.5mg per day. A single larva needs to be fed something like 30mg of protein, which works out to be around 100-200mg of pollen, depending on the variety. It is of course not just protein, but a portion of ten amino acids.[ii] The only way the bees have of obtaining these essential amino acids is by consuming them and then using them to make all the proteins they need. In addition, pollen provides lipids,[iii] including essential fatty acids,[iv] starch, fibre, vitamins, and minerals.

Of these, one thing we haven’t studied much is the minerals. At a most fundamental level, honey bees are collections of individual elements, atoms which cannot be converted into different atoms (in contrast to the organic compounds which can be ‘repurposed’). If you studied chemistry you will remember ‘stoichiometry’, probably not fondly. From the very formation of a bee all chemical elements that form that body of the adult must be assembled in the right proportions, so these must exist in their food. To ‘make’ a bee, apart from the atoms of carbon, hydrogen, and oxygen found in carbohydrates (and nitrogen in proteins), all the other atoms are going to come from pollen. Some of these atoms[v] are often deficient in the pollen sources available to the hive and that has the potential to limit the number of bees that can be ‘made’.[vi] For example, the eucalypt pollens, and kiwifruit, all appear to lack sodium, and that might be why bees sometimes seem to like ‘salty’ water.

Lipids are a large group of organic molecules defined by their insolubility in water. Chemists subdivide the group into eight more precise groups of molecules like fatty acids, glycerols, sterols and others. To most of us they are all the waxes, fats and oils that make up living structures. They store energy, insulate, and act as chemical messengers – the hormones that modulate bee behaviour. The sterols are components of the membranes of all plant and animals’ cells (in your case its cholesterol), and a small amount of sterols are important in bees for ovary and egg development and for producing the moulting hormone, makisterone.

There’s a range of pollen substitutes on the market for beekeepers to provide their honey bees, but delivery of a complete diet has thus far eluded beekeepers and scientists alike.

An inherited hiccup

An accident of evolution that happened long before bees were bees makes sterols particularly important. 600 million years ago, the ancient ancestors of all insects, (the Ecdysoza; as ecdysis means to moult a cuticle or ‘outer skin’), gave up the ability to make the sterols they need.[vii] The Ecdysoza and all their descendants rely on phytosterols made by plants. This has made it both important and more difficult to understand steroid metabolism in bees and, in social bees, how they are conserved and transferred among the nestmates.[viii] Unfortunately sterol analysis techniques for insects are not particularly well developed.[ix]

Biotechnology steps in

This April a group of biotech entrepreneurs, largely from a Belgian company called Apix Biosciences, published some work on a ‘nutritionally complete’ pollen replacement diet. Developed with collaboration from scientists at the universities of Washington, Newcastle, Pretoria, and the Hebrew University of Jerusalem, Apix Biosciences is hoping for commercial release of the product in the US sometime in 2026, with an eye on a claimed five billion kilogramme market demand. I ought to note at this point that the company is currently raising venture capital to fund the product.

According to the paper[x] the key to its success was the discovery – by selectively removing nutrients from diets fed in cage trials – that one particular sterol, isofucosterol, is much more important than had been previously realised, essential actually. Without it, brood production declined and the bees suffered with neuromuscular impairment. In field trials with the University of Washington 64 colonies used in blueberry and sunflower pollination (known for its nutritional stress) the new ‘complete’ diet successfully mitigated the season’s ill-effects compared to available alternatives. It might indeed be a promising solution.

This study challenged the ‘essential’ status of the main sterol found in honey bees, 24MC, inferred in previous work since the 1980s.[xi] Time, and more research, will tell whether the new study is right, but it underscores the importance of a more complex and nuanced understanding of dietary sterols for honey bee’s nutrition, and of the importance of organising a resilient variety of forage opportunities for them.

You can’t buy honey bee health. Not for the moment, at least.

Dave Black is a commercial-beekeeper-turned-hobbyist, now retired. He is a regular science writer providing commentary on “what the books don't tell you”, via his Substack Beyond Bee Books, to which you can subscribe here.

References

[i]Huang Z. Feeding honey bees. Michigan State University Extension Bulletin E-3369. 2018;1-3.

[ii]Arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.

[iii]Especially the sterols, 24-methylenecholesterol (24MC), beta-sitosterol, isofucosterol, campesterol, cholesterol, and desmosterol.

[iv]Palmitic, linoleic, alpha-linolenic, oleic and stearic.

[v]Sodium, sulphur, copper, phosphorous, potassium, and zinc.

[vi]Filipiak, M., Kuszewska, K., Asselman, M., Denisow, B., Stawiarz, E., Woyciechowski, M., Weiner, J., 2017. Ecological stoichiometry of the honeybee: Pollen diversity and adequate species composition are needed to mitigate limitations imposed on the growth and development of bees by pollen quality. PLoS ONE 12, e0183236. https://doi.org/10.1371/journal.pone.0183236

[vii]Brunoir, T., Mulligan, C., Sistiaga, A., Vuu, K.M., Shih, P.M., O’Reilly, S.S., Summons, R.E., Gold, D.A., 2023. Common origin of sterol biosynthesis points to a feeding strategy shift in Neoproterozoic animals. Nat Commun 14, 7941. https://doi.org/10.1038/s41467-023-43545-z

[viii]Vanderplanck, M., Zerck, P., Lognay, G., Michez, D., 2020. Generalized host‐plant feeding can hide sterol‐specialized foraging behaviors in bee–plant interactions. Ecology and Evolution 10, 150–162. https://doi.org/10.1002/ece3.5868

[ix]Furse, S., Koch, H., Wright, G.A., Stevenson, P.C., 2023. Sterol and lipid metabolism in bees. Metabolomics 19, 78. https://doi.org/10.1007/s11306-023-02039-1

[x]Bogaert, T., Reams, T., Maillet, I., Kulhanek, K., Duyck, M., Eertmans, F., Fauvel, A.M., Hopkins, B., Bogaert, J., 2025. A nutritionally complete pollen-replacing diet protects honeybee colonies during stressful commercial pollination—requirement for isofucosterol. Proc. R. Soc. B. 292, 20243078. https://doi.org/10.1098/rspb.2024.3078

[xi]Chakrabarti, P., Lucas, H.M., Sagili, R.R., 2020. Novel Insights into Dietary Phytosterol Utilization and Its Fate in Honey Bees (Apis mellifera L.). Molecules 25, 571. https://doi.org/10.3390/molecules25030571