A number of stress factors acting on bees in a so-called cocktail effect can cause colony death. In particular, the low quality and low diversity of pollen and the substitution of sugar for honey is identified as one of the causes of a significant reduction in bee immunity to disease from the larval to the adult stage. In addition, there is virtually no effective and safe agens useful for suppressing the spores and growth of the culture of Paenibacillus larvae, the bacterium causing the bee foulbrood, which is the most important current bee disease. This disease has been controlled for many years with pyrethroids, organophosphates and anti-biotics, which can subsequently contaminate bee products, especially honey. Feed for bees according to this technical solution containing sugar, water and 0.1 to 20% by weight of Chlorella sp. algae in the form of dried algal biomass is an attractive food for bees and represents a varied source of nutritional substances in a period that is poor in natural pollen sources. In addition, it has been shown to have a positive effect on increasing health resistance. Secondary metabolites of algae generally differ from higher plants, fungi and bacteria not only in their chemical structure but also in their spectrum of biological activities, such as antibacterial, allelopathic, antiviral, fungicidal activity or inhibitory effects against a number of enzymes. The composition of the biomass of this algae is varied, very similar to pollen, with a high protein content (up to 40-60%) and also contains a group of substances that have an inhibitory effect on the causative agent of the foulbrood, the bacterium P. larvae.
