In vitro activity of essential oils from San Luis-Argentina against Ascosphaera apis

From the eight oils evaluated in the vegetative cycle of the fungus, six of them-T. absinthioides, H. latifolia, A. gratissima, L. juneliana, L. integrifolia and L. turbinata-exhibited fungicidal activity against A. apis. On the other hand, the oils of B. coridifolia from female plants and of E. patens did not exhibit any fungicidal activity.

Table II shows the principal compounds (> 5%) of the oils screened. The T. absinthioides oil contained caryophyllene oxide as its principal component (9), B. coridifolia isocaryophyllene and [beta]-caryophyllene (10), H. latifolia borneol and camphor (11), A. gratissima epi-[alpha]-cadinol and caryophyllene oxide (12), E. patens [beta]-caryophyllene and [gamma]muurolene (13), L. juneliana piperitenone oxide and limonene, L. integrifolia [beta]-caryophyllene and L. turbinata limonene and piperitenone oxide (14).

Colin et al. (15) studied other species for the in vitro control of A. apis: the oils of two varieties of Origanum vulgare, Satureja montana and 16 clones of Thymus vulgaris. The most effective oils were the O. vulgare variety from Drome, S. montana and the clones 756, 133, 077 and 557 of T. vulgaris. The S. montana oil consists of four main compounds: carvacrol (31.5%), p-cymene (20.8%), [gamma]-terpinene (11.8%) and thymol (4.2%). The T. vulgaris in the clone 756: p-cymene (25.3%), thymol (9.7%) and carvacrol (39.9%), the clone 133: p-cymene (22.2%), thymol (10.1%) and carvacrol (38.6%), the clone 077: p-cymene (28.6%), thymol (8.7%) and carvacrol (32.0%) and the clone 557: p-cymene (31.3 %), thymol (5.7%), carvacrol (27.3%) and linalool (8.4%). The oils that showed more antifungal activity had carvacrol concentrations of more than 30%.

Bazzoni et al. (16) have studied the oils from the following species: T. capitatus, T. herba-barona, Rosmarinus officinalis (three samples), Myrtus communis, Eucalyptus globulus, Salvia desoleana, S. officinalis, Helichrysum italicum and Cinnamomum species. The oils that had an effect against A. apis were: T. capitatus that contained carvacrol (68.01%), [gamma]-terpinene (6.33%) and p-cymene (6.17%) as its main components T. herba-barona contained carvacrol (60.04%) and p-cymene (6.16%), Cinnamomum species contained cinnamicaldehyde (79.3%) and eugenol (11.9%) and H. italicum contained neryl acetate (51.59%) and nerol (8.22%).

Larran et al. (17) used oils from species cultivated in La Platazone: coriander (Coriandrumsativum L.), laurel (Laurus nobilis L.), false camphor (Cinnamomum glandulifera Nees), basil (Ocimum basilicum L.), tagetes (Tagetes minuta L.), rosemary (R. officinalis L.), eucalyptus (Eucalyptus globulus Labill), and lavandin (Lavandula xintermedia Emeric ex Loiseleur). All were assayed to prove their fungistatic activity at different concentrations: 700, 800 and 900 [mu]L/L. At all concentrations tested, coriander oil was the most effective fungistatic control while basil and tagetes oils were effective only at 800 [mu]L/L. Coriander and basil oils contained linalool as their main compound (68,4% and 42.3%, respectively), and tagetes oil contained (Z)-[beta]-ocimene (44.3%) and (Z)-ocimenone (12.2%).