In case of extracts, common hop (Humulus lupulus L.) and myrtle (Myrtus communis L.)
methanolic-dichloromethane extracts exhibited the highest growth-inhibitory effect with
MICs ranging from 2 to 8mg/ml. Acute oral toxicity of themost active natural products was
determined on adult honey bees, showing them as non-toxic at concentrations as high as
100 mg peer bee.