Untersuchungen über das Zuckerbild der Hämolymphe der Honigbiene ( Apis mellifica L.)—I. Das Zuckerbild des Blutes Erwachsener Bienen

Abstract

The blood sugar spectrum of the adult honeybee ( Apis mellifica L.) has been analysed by paper chromatography. Blood of emerging worker bees, drones, and queens does not contain measurable quantities of sugar. The blood chromatograms of all bees examined show negative spots (clearer than the background) which are localized at the level of maltose (probably trehalose) and between glucose and sucrose. In the blood of 24-hr-old worker bees and drones emerged without help and having had the possibility of feeding on the comb, fructose and glucose and sometimes other sugars (sucrose, maltose, fructomaltose, oligosaccharides) can be detected quantitatively. Generally fructose predominates. This sugar spectrum is characteristic for the blood of marked summer bees up to the age of 3 weeks, of winter bees, and of drones in the free-flying colony and for caged bees put on a sugar or pollen diet. Protein food (pollen, casein) and the origin (race) of bees do not influence the sugar spectrum of the blood. Blood of older (4–5-week-old) summer bees captured in the colony does not contain measurable quantities of sugar; foragers captured outside the colony have blood with abundant sugar (fructose, glucose, also often sucrose and other sugars). Blood of worker bumble-bees and drones of unknown age ( Bombus lapidarius, Bombus hypnorum, and Bombus pratorum) has a similar sugar spectrum. Experimentally produced Nosema infections did not influence the sugar spectrum of the blood; a spontaneous septicaemia infection made the sugar disappear in the blood. Feeding experiments with pure solutions of nine sugars showed that the monosaccharides (fructose, glucose, galactose) pass directly into the blood. Compound sugars (sucrose, maltose, melezitose, trehalose) are hydrolysed, and appear mostly as breakdown products (fructose, glucose) in the blood; they can be partly detected in unchanged form (melezitose, sometimes sucrose and maltose). Sugars poisonous for bees (melibiose, raffinose) appear neither directly nor in hydrolysed form in the blood. The bees get paralysed and die after having consumed the original sugars. Galactose also is poisonous for bees. In contradistinction to higher animals, the blood sugar spectrum of the honeybee is not constant but directly dependent on the food composition. The ‘normal’ blood spectrum of bees of the free-flying colony is the reflection of sugars absorbed with the food (nectar, honeydew, honey, sugar) or of their hydrolysis products.