Honeydew: chemical composition and why do bees collect it

Underestimated in some countries as a honey with poor quality and in other praised as a treat, honeydew has been for a long time a subject for discussion among bee keepers. Long ago it was known that honeydew is not suitable food for bee hibernation. What is actually honeydew, and why do bees collect it?

Honeydew is a sweet secretion of some insects, and it is collected by bees, especially when sources of natural nectar are scarce. It is often considered that the honeydew is unwanted ingredient of flower honey. It mainly dark color and has a strong smell like molasses. For honeydew people usually think that the honey is poor quality and that can be used only in baking industry.

Honeydew however can be various, such as different types of nectar that is collected by bees. Not only that insects that feed on various plants produce different types of honeydew, but different types of insects that feed on the same type of plant do not produce honeydew of the same composition. Honeydew is not always dark color, and it doesn’t always have a strong smell. You can come across of honeydew of light color with the taste of flower honey.

Insects that produce honeydew feed on plant juice of the plant where they live. Their mouths are adapted to penetrate the tissue of the plant and from it suck out the plant juice. In fact, insect only partially consumes the juice from the plant by directly sucking it in. these insects have in their mouth a special tube, through which from saliva they release enzymes into the tissue of the plant. These enzymes stimulate the plant to secrete sweet juice, but at the same time help creating complex sugars.

Various types of insect find food in different parts of the plant, although the biggest producers of honeydew are those insects that drain the juice directly from the plant tissue. Aphids are most generous in secreting honeydew, and are located in the oak, beech, lime, poplar, willow, maple and some fruit trees. Aphids live in conifers, so thanks to them abundant yields of honeydew are received in those areas rich with this tree.

Apart from aphids numerous other insects secret honeydew, all of them are capable to suck in great amounts of juice, and from it extract necessary ingredients, and to expel excess substances and prevent them to become hardened excrement. When aphids multiply so much you can see the leaf and tree covered by honeydew, it even covers the ground surrounding the tree.

Immediately after secretion honeydew is colorless, but under the influence of the air it receives light brown color. One degree of coloration certainly comes from dust and dirt. These substances not only influence the color, but the taste of honeydew. Honeydew in average contains 5-18% of dry matter upon secretion, and after the drops hardens, dry matter rise to 35-50% or more. Degree of drying influences on the maturity of honey in the process of turning honeydew into honey.

Chemical composition:

Chemical composition is considerably different from flower nectar. Differences are mostly created because of passage of juice through insect’s intestine.

Honeydew always contains enzymes of saliva glands and intestines. Invertase, diastase, peptidase and protease are identified in honeydew, and these enzymes cause the difference in honeydew, especially there is a difference in the specter of carbon hydrates.

Sugar content varies considerably. Saccharose is a predominant sugar in plant juice and it is dissolved in insect intestines. That is why in, processed honeydew, glucose and fructose are mostly present in large percentages, according to some measures, the average of fructose 31,8%, glucose 26,08%, saccharose 0,8%. Other sugars are located in honeydew. There also identified: raffinose, and maltose melecitoza. Occasionally a presence of trehalose and fructose maltose was occasionally determined. Of other sugars there are: melibioza, mannose, rhamnose and stachyose. It has been pointed out that some of these sugars are poisonous for bees, such as raffinose and melibioza.

Honeydew can contain sugar phosphates or sugar alcholos: inositol and sorbitol.

Will the BEES collect honeydew, will depend not only on other sources o nectar, but on the amount and quality of sugar in honeydew.

Honeydew contains considerable number of nitrous components. Nitrous content in honeydew varies from 0,2-1,8% of dry matter. 70-90% of this is amino acids and amids. Certain number of other components is typical for honeydew: organic acids, lemon and apple, amber, fumaric acid and isocitric acid are identified somewhere.

Honeydew regularly contains mineral salts: potassium, chlorine and sulfur. Nitrate and ammonia are also indentified.

There are following tests:
1. Alcohol. One part of the honey is dissolved in the same amount of water. To this solution you add 96% alcohol. If there is honeydew, the solution becomes dim and at the bottom of the tube there is a deposit. In the contrary the solution remains clear.
2. Test by lime water. Clear water from freshly slaked lime is mixed with the same amount of water solution of honey. It is shaken and heated on a mild fire until it boils. If there is honeydew the compound becomes dim, and sediment fall to the bottom.