Paper deals with the effect of the botanical preparation BioNEEM™ on growth and pathogenicity of various ecotypes of entomopathogenic fungusBeauveria bassianaas well as comparison of its effect with effect of pyretroid Fastak on ecotypes of this species. Investigations were carried out under controlled laboratory conditions. It was found that at the field dose various ecotypes ofB. bassianareact differently to contamination of substrate with the preparation examined. These differences are relatively small and do not change the role played by this fungus in the environment.B. bassianais active in the habitat where both preparations are present.