Bee Choice of Food Source and Processing Inside the Hive: Two Essential Mechanisms to Determine Bee Product Quality[Editor's Note: The following presentation were offered at the 6th German Apitherapy and Apipuncture Congress held in Passau from March 27th to April 1st, 2008]
By Janko Božič, University of Ljubljana, Biotechnical faculty - Department of Biology, Večna pot 111. 1000 Ljubljana, Slovenia, Contact: janko.bozic@bf.uni-lj.si
Major components of honey derive outside of the bee hive. Nectar and honeydew have to be collected by the bees and brought inside of the hive where processing and maturation from food source sugar solutions into valuable honey occurs.
Along with the most abundant sugars - glucose, fructose and sucrose - bees also collect other organic and inorganic compounds that are secreted from nectarous glands or by honeydew’s producers.
Plants attract pollinators not only by sugar rewards but they often secrete chemical signals that can trigger research foraging behavior in pollinating bees and further help the bees to stay along the same well-rewarded patch of flowers.
In case of honeydew producers, secretions are actually excretes and bees collect it due to its high sucrose level. Content of the honeydew depends more on physiology of the aphids or scale insects, which are most often source of honeydew. Secretions often contain oligosaharides, which are usually the result of complex physiological and biochemical processes inside of the aphid’s or scale insect’s intestine. There are also other compounds related to the host plant metabolism and physiology.
Special waggle dance communication within the hive enables selection of food sources with the highest profitability. This usually means that bees forage the most profitable food source. Some bees don’t follow the major foraging groups and keep foraging on their own food source.
No significant research has been done on these minor foraging groups inside bee colony. A hypothesis can be developed that this minor foraging could bring some special nectar or honeydew source, which can give specific quality attributes to the final stored honey. One of the crucial steps in investigation would be olfactory preference of different foraging bees: pollen, nectar or honeydew and plant resins collectors.
This is the first possible step in honey production in which bees can significantly contribute to the final quality of the honey. Possible known manipulations of the bees related to the food preference and selection are discussed.
The major contribution of the bees is related to the processing of the nectar and honeydew into the honey. The best known contribution is secretion of two enzymes. Alfa glycosidase contributes to the reduction of sucrose level and increase of fructose and glucose level. An additional enzyme, glucose oxidase contributes significantly to the antimicrobial activity of the honey by producing hydrogen peroxide.
Both enzymes are secreted from hypo-pharyngeal gland of the foraging bees. In younger nurse bees, this gland produces royal jelly proteins. It has been shown that food exchange inside of the hive contributes to the passage of nurse bee secretions into the honey.
It is not well know how much and which compounds are perhaps also secreted by other glands with the secretions inside of oral cavity. There are several possibilities to manipulate honeybee behavior and physiology to increase potential secretions into the honey. Some have already been practice, but detailed technology is under development.
View a PDF version of the presentation.
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