Microflora in the honeybee digestive tract: counts, characteristics and sensitivity to veterinary drugs

Experiments were carried out to enumerate and characterize the microorganisms in the midgut and rectum of the honeybee. Counts of aerobic microorganisms were distinctly lower than counts of anaerobes (10(4)-10(5) viable cells per gram of intestinal contents versus 10(8)-10(9) per gram). Total numbers of anaerobic microorganisms were almost identical with counts of anaerobic Gram-positive acidoresistant rods. These bacteria represent the principal groups of microorganisms in the bee digestive tract. Anaerobic and aerobic microorganisms, lactobacilli, coliforms, staphylococci, Bacillus sp, and yeasts were found in all bees. Only one out of 31 isolates (Bifidobacterium asteroides) was identified at the species level. Fluvalinate, fumagillin and nystatin significantly increased mortality of bees. Treated bees kept in cages contained more yeasts than control bees in the beehive. The veterinary drugs tested significantly increased counts of yeasts in comparison with the control.