[Role of mildew and mildewed honey in summer-fall mortality in bee hives].

The high summer and autumn lethality of unknown etiology observed in bee families from the Vidin district in 1978 was studied. It was established that amid suffering bee families lethality ranges from 50 to 100%. Results of the microbiological investigations carried out proved negative--no pathogen bee microorganisms were isolated. Negative results were obtained from the parasitological investigations also. Analysis of honey produced by suffering families indicated that the samples are highly positive for mildew affected honey and negative for other poisons. Histological investigations of the mid intestine of live bees from the affected families showed changes characteristic for mildew toxicosis. Laboratory biotests carried out by feeding healthy bees with honey taken from suffering or dead bee families confirm the diagnosis. The experimental bees revealed the typical clinical picture and characteristic symptoms of mildew toxicosis and high lethality.