Antimicrobial Activity of Some Essential Oils AgainstPaenibacillus larvae, the Causal Agent of American Foulbrood Disease

Essential oils from savory (Satureja hortensis), lavandin (Lavandula hybrida), eucalyptus (Eucalyptus globulus), lemon grass (Cymbopogon citratus), peppermint (Mentha × piperita), oregano (Origanum vulgare), rosemary (Rosmarinus officinalis), and thyme (Thymus vulgaris) were tested for antimicrobial activities against Paenibacillus larvae, the causal agent of American Foulbrood Disease (AFB) of honey bees. Trials for determining the minimum inhibitory concentration (MIC) of these oils revealed that lemon grass and thyme were the most effective with MIC values between 50 to 100 $mUl/liter and 100 to 150μl/liter, respectively, in tests with 8 Paenibacillus larvae strains from different Argentinean geographical regions. The findings indicate that lemon grass and thyme oils could be used as effective inhibitors of AFB in honey bee colonies.