Laboratory evaluation of Heterothalamus alienus essential oil against different pests of Apis mellifera

The Heterothalamus alienus oil was investigated in laboratory for control of different pests that affect the colonies of bees, Apis mellifera, against Varroa destructor mite, the bacterium that causes the American Foulbrood, Paenibacillus larvae and the fungus that produces the chalkbrood, Ascosphaera apis. The oil composition was analyzed by GC and GC/MS, the main components of the oil were beta-pinene (44.4%) and trans-muurola-4(14),5-diene (9.2%). The concentration to kill 50% of the mites in 24 h (LC50) was 0.59 mg/cage. Inferior and superior limits were the following ones: 0.34 mg/cage and 1.01 mg/cage, LC50 was estimated for 48 h, and 72 h showed a slight increase with respect to the record of the 24 h. Paenibacillus larvae strains were Grain positive and catalase negative, the oil presented MIC values of 800-900 mg/L and MBC of 1000-1200 mg/L. Disks of impregnated filter paper with H. alienus oil around colonies of A. apis in growth inhibited the micelial growth significantly by 51% in the first experiment (seven days) and by 31% in the second experiment (eight days).