TRANSMISSION OF PAENIBACILLUS LARVAE SPORES THROUGH SOCIAL CONTACTS WITHIN HONEYBEE COLONIES (APIS MELLIFERA CARNICA POLLMAN, 1879)

American foulbrood is a widely distributed, very persistent honeybee disease, caused by the spore forming bacterium Paenibacillus larvae. The disease is highly contagious and unless recognized at an early phase, can give rise to significant losses for beekeepers. The purpose of this study was to investigate what would happen with the level of P. larvae spores concentration in honey sacs during the transmission of food through social contacts and during various times of digestion of the spore contaminated food. A method described by Ritter and Kiefer (1993) for determining the presence and the number of P. larvae spores in honey samples was modified in a way that through the number of the grown P. larvae colonies on MYP agar it was possible to determine the concentration of P. larvae spores in the honey sac of individual bees. Regardless of the quantity of food delivered through social contacts, the known concentration of P. larvae spores remained unchanged. After various times of digestion, the concentration of P. larvae spores was also constant. Therefore, the ability of honeybees to reduce the number of P. larvae spores from their honey sac by filtration was not proven.