1. Institute of Animal Science, Apiculture Division , Nowoursynowska 122 , Warszawa , Poland
2. The National Institute of Horticultural Research, Apiculture Division in Puławy , Konstytucji 3 Maja1/3 , Skierniewice , Poland
3. Institute of Animal Science , Departament of Animal Environment Biology , Ciszewskiego 8 , Warsaw , Poland