During the summer of 2016 there were some reports in the Netherlands about ‘concrete honey’. This ‘honey’ tends to cristallize very strongly. As a consequence, bees are not able to consume it. Concrete honey, and its milder variant cement honey, has a high content of melizetose. Melizetose is a trisaccharide, consisting of 2x glucose + 1x fructose. In fact it is normal sugar (saccharose) to which another glucose is attached.
Always beware of melizetose
The beekeeper should always be aware about a possible supply of melizetose, in particular when the bees forage on chestnut or linden, or when larch trees are within flying distance. In case of larch, melizetose seems to originate from honey dew produced by scale insects. In the literature also plants from the ranunculaceae (for instance buttercups) are mentioned as sources of melizetose. Without doubt there are even more plants which produce this sugar.
Disadvantages of melizetose
The disadvantages of melizetose for the bees can be prevented by administering additional sugar. This way the melizetose is diluted, and the bees do not suffer from the detrimental effects.
The concrete honey casus was a reason for me to pay some attention on the subject ‘sugar’ and honey bees.
In fact, glucose is the only useful sugar for bees, glucose is the only source of energy they can utilize. Fructose is only utilizable in the presence of a certain type of lactic acid bacteria. In case this lactic acid bacteria is not present, about half of the regular sugar saccharose, for instance in the winter sugar feeding, is unusable for the bees. Plain sugar is not utilizable directly for bees, as is melizetose. These sugars must firstly converted into utilizable sugars. This takes place by micro organisms, present in the gut of the bees and on other parts within the bees (e.g. mouth parts) and in the rest of the bee system.
Sugars in honey
According to the corresponding chapter in the book Food Chemistry, in total up to 40 different sugars occur in honey. By far the most part consists of the so called mono sugars glucose and fructose, sometimes also galactose. Particular sugars consist of special combinations of glucose and fructose, but also some ‘higher’ saccharides are present, i.e. sugars consisting of 3 or more mono sugars connected to each other. Normally these special sugars in honey occur in small quantities, on average 1,5% in the range 0,1 – 8,5%.
Also mono sugars other than glucose and fructose are worth mentioning. The mono sugars galactose and mannose are toxic for bees. These sugars originate from the hemicelluloses in the cel walls of pollen. The same holds true for pectic sugars (galacturonic acid), these are not good for bees.
The importance of sugars in relation to bee health can be illustrated from the fact that the presence of stachyose (a tetra sacccharide, consisting of 2x galactose, 1x fructose and 1x glucose) in patties made from soy beans lead to colony loss, in particular when these patties are fed to bees in autumn.
A sugar, which should not be forgotten in this short overview, is trehalose. This is a disaccharide, which occurs as a storage sugar in the muscles of the bee flying system. It is composed of 2x glucose. Due to the alfa bound between the glucoses, trehalose can easily be converted into glucose on behalf of the energy supply during flight.
Program bee health
As a part of my program for bee health I have asked some beekeepers to administer pure glucose to their bees during the season. I am waiting to hear their findings. This is a simple practical research item, which can be of benefit for all beekeepers and which does not cost millions.