Most people agree that honey is superior to sugar, for humans that is. It becomes all the more incomprehensible that the same people with firm conviction claim that sugar is as good as honey for bees, some even claim that honey would be dangerous/poisonous for bees. We’ve all heard and read how dangerous heather honey is as a winter food, right? Then some finally admit that the low price of sugar is the main reason.
The majority of beekeepers therefore collect all the honey in the autumn and exchange it for sugar water. The arguments for doing so are a bit different – some claim that the bees just sit still and therefore don’t need anything other than carbohydrates and therefore sugar is fine. Some claim, as allready mentioned, that honey is toxic to bees, for example autumn honey is said to cause dysentery due to the high content of minerals.
Concrete research on the importance of food for the development and longevity of bees is rare, especially field studies. Barker 1977 (1) found in his study that sugar gave a significantly longer lifespan than honey in a laboratory environment. The opposite result was obtained by a later study, significantly better performed because it was repeated three years in a row, by Milenovic et al (2) where bees fed with honey fared slightly better than with sugar water (difference not significant). There it was also found that acid inverted sugar was dangerous for the bees as the residual acid negatively affected the stomach. DeGroot already showed in 1953 (3) in his study that bees can survive on pure carbohydrates for about 30 days and that protein is necessary for longer life. DeGroot also showed that bees’ need for essential amino acids is similar to that of mammals, while studies on the effect of minerals and vitamins are lacking. Studies (4,5) on mammals have shown that they need vitamin B to regulate the intake of proteins and carbohydrates as well as nutrient absorption and metabolism. As mentioned, there are few studies on bees’ need for vitamins, but studies that have been done show, among other things, that Vitamin B, just like for mammals, improves nutrient absorption and makes the bees use their food in an optimal way. Haydak and Dietz (6), 1965 showed that vitamin B is required for growth of the larvaes and lack of thiamine or riboflavin stopped the development of the hypopharyngeal glands (HPGs) (7) after the young bees crawled out of the cells. In a new study from 2021 with young bees (that have just crawled out of the cells) where different diets were tested with respect to Vitamin B and amino acids, it was found that mortality increased when B vitamin was lacking (8). In addition, it was found that the bees preferred diets with mineral and vitamin content similar to what is found in natural pollen, see table below.
Practical application: During the bee’s development from egg to larva and to the finished bee, proteins, minerals and vitamins are needed in addition to carbohydrates. The big question then is whether carbohydrates alone are enough when the bees are in clusters?
The above question can then be divided into two different parts:
a. Do the bees make brood during the winter, which would require a great need for both proteins, carbohydrates as well as minerals and vitamins?
b. Do older bees need anything more than carbohydrates for maintenance during the winter?
Let’s start with the first point – do bees brood during the winter? For a long time I thought that winter nrood was something to be avoided because it increases food consumption and thus increased the risk of dysentery. That’s what we were taught on the beginner’s course and to avoid this, the bees should be crowded, i.e. preferably winter in only one box. This misconception/myth was thoroughly debunked by the article series on dysentery that Randy Oliver wrote. In a study from 1935, Alfonsus (12) showed that the real cause of dysentery is excess water in the rectum. Therefore, bees need to brood as a last resort to get rid of excess water (9). Brood-laying costs the bees a lot of energy, partly because the existing bees age from the brood handling and partly because it requires extra food to raise the brood but also for the higher temperature that brood care requires. Still, they do this and the reason is that if they don’t, they can’t get rid of the excess water and finally dysentery happens in the colony. This insight means that the need for high quality pollen is needed throughout the year and must be in the food box because the bees cannot leave the cluster to collect pollen further down in the hive. However, this does not automatically mean that older bees need anything other than carbohydrates.
Practical application: Bees make brood, when necessary, even during the winter, as a last resort to get rid of excess water. Therefore pollen must be in the feeder box.
Then the question remains whether older bees can survive on carbohydrates alone. DeGroot found in his study that the lifespan of both young bees and older bees increased significantly when the bees received proteins equivalent to what is found in pollen, but that the amount needed by the older bees was considerably lower than what the young bees needed. In addition, older bees refrained from eating pure protein supplement but preferred to eat sugar solution containing protein. The amount of protein needed to keep the protein levels constant was at levels corresponding to what is found in honey, see table below.
The table below compares the lifespan of older bees fed pure sugar and sugar with the addition of pollen bread or pollen substitute. Older bees can obviously eat pure pollen but also get a longer lifespan from the amount of pollen found in honey. Milk protein gave longer lifespan but only in the right concentration (1% or lower) in higher levels the lifespan was shortened.
Practical application: Brood raised on sugar alone become weak and have a short lifespan because the amount of protein found in the bees’ fat body is not enough to raise brood. If bees are forced to brood without adequate amounts of protein, the bees may eat the eggs and young larvae (10).
Older bees that hibernate on sugar alone lose weight and thus their lifespan. Even older bees thus need proteins, vitamins and minerals to maximize their lifespan in the winter cluster. Their needs are less than the young bees, because they only need to maintain the body and the amounts needed are found in the honey (enough protein to keep the weight constant). For growth, higher levels are needed which are found in pollen bread and royal jelly.
In a Polish study (11), hives with different levels of honeydew (0-30%) were tested over three years, where no difference was found in winter losses between 0% and 30% honeydew in the winter food. However, it was found that 10% or more honeydew significantly reduced the amount of Nosema spores in the colonies, whether it is specific to honeydew or whether all honey has this effect is unclear. Table 2 shows that the content of honeydew does not affect the winter losses (0% honeydew has the same loss as 30% honeydew). Table 3 shows how the degree of Nosema-infected colonies decreases with increasing honeydew content.
Practical application: the above study indicates that honeydew boosts the immune system. Unclear if this applies only to honeydew or to honey in general. More research is needed.
A lot of research is needed to understand in detail how bees’ metabolism works, but to claim that bees survive just as well on pure granulated sugar is obviously not true. If sugar is to be used, you need to add both proteins in the right amount and correct distribution of the essential amino acids, but also vitamins and probably minerals. In the end, you get a product that is a bit like honey, but unatural, and you can question the point of it. It is important that one add the protein to the sugar and not give it to the bees as a protein cake because the bees tend to not eat it that way.
What is definitely lacking are field studies comparing pure sugar colonies with colonies that are allowed to keep their honey and pollen in the right amounts. Bees survive on a pure sugar diet, but the question is how well they survive and if there is a measurable difference between sugar colonies and honey colonies. To my knowledge, such studies have not been done and therefore we plan to carry out such a study on a smaller scale next season.
Ví have already tried winter in on honey and pure sugar, but in separate years, and there we saw clear differences in how the bees survive the winter. In both cases all the bees survived, but when pure sugar was used the bees were weak in the spring and took a long time to get strong. Not until the middle of June had the sugar colonies reached a bee strength that could produce a surplus, while colonies receiving honey were strong and produced a surplus as early as the beginning of May. If this effect was due to how the winter was or if it has to do with the food, we will hopefully get an answer in the next comparative study.
In the coming study we will measure what the bee strength looks like before and after the winter, what the development looks like and how well the colonies are doing the following summer.
Referencies
1. Barker, Labarotory comparison of high fructose corn syrup, graper syrup, honey and sucrose syrup as maintenace for caged honey bees
2 . http://www.resistantbees.com/fotos/estudio/feeding.pdf.
3. De Groot, Protein and amino acid requirements of the honeybee.
4. Gonzalez-Soto, M., and Mutch, D. M. (2021). Diet regulation of long-chain
PUFA synthesis: role of macronutrients, micronutrients, and polyphenols
on 1-5/1-6 desaturases and elongases 2/5. Adv. Nutr. 12, 980–994.
doi: 10.1093/advances/nmaa142
5. Dabrowski, Z. (1974). Studies on the relationships of Tetranychus urticae Koch
and host plants. V. Gustatory effect of water-soluble vitamins. J. Polskie
Pismo Entomol.
6. Haydak, M. H., and Dietz, A. (1965). Influence of the Diet on the Development and
Brood Rearing of Honey Bees. Proc. XV. Beekeeping Cong. Bucharest.
7. Herbert Jr, E. W., Shimanuki, H., and Caron, D. (1977). Optimum protein levels
required by honey bees (Hymenoptera, Apidae) to initiate and maintain brood
rearing. Apidologie 8, 141–146
8. Walaa Ahmed Elsayeh 1,2*, Chelsea Cook 3 and Geraldine A. Wright. (2021) B-Vitamins Influence the Consumption of Macronutrients in Honey Bees
9. Omholt, SW (1987) Why honeybees rear brood in winter. A theoretical study of the water conditions in the winter cluster of the honeybee, Apis mellifera J. Theor. Biol. 128: 329-337.
10. Robert Brodschneider and Karl Crailsheim (2010). Nutrition and health in honey bees
11. Healthfulness of honeybee colonies (Apis mellifera L.) wintering on the stores with addition of honeydew honey
12. Alfonsus, E. C. (1935). The cause of dysentery in honeybees. Journal of Economic Entomology, 28(3): 568-576.
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