L’activité antibactérienne de plusieurs huiles essentielles sur les formes végétatives et spo- rulées de six souches de Bacillus larvae White, agent de la loque américaine, a été évaluée in vitro. Les résultats indiquent que les huiles d’oranger (Citrus sinensis), cannelle (Cinnamomum sp), cumin (Cuminum cyminum), giroflier (Eugenia spp), thym (Thymus vulgaris) et verveine (Verbena) présen- tent in vitro des pouvoirs bactéricides et sporicides ; celle de la cannelle a montré la meilleure activité, avec une concentration minimale bactéricide de 50 ppm et sporicide de 100 ppm. À la concentration de 400 ppm, incorporée dans le candi, cette huile a été efficace aussi contre la loque américaine dans une expérience en rucher. L’aromathérapie peut donc permettre de contrôler la loque améri- caine sans avoir recours ni aux sulfamides ni aux antibiotiques et de préserver le caractère naturel du miel.
The action of 21 essential oils against six strains of Bacillus larvae White, the causal agent of American foulbrood of honeybees, was studied in vitro. In a preliminary trial (table II) the effectiveness of either pure or diluted (1:5) oils was assessed by the diffusion agar method (Carta et al, 1989). The more effective ones were then tested in nutrient broth, at doses ranging from 50-400 mg/kg, to determine the minimal bactericide and sporicide concentrations. The most significant results were obtained with the oils of Citrus sinensis, Cinnamomun sp, Cuminum cyminum, Eugenia spp, Thymus vulgaris and reconstituted oil of Verbena (tables III and IV, fig 1). The same oils proved to be non-toxic for adult honeybees at the dose of 400 mg/kg. Cinnamomun oil was the most effective, with minimal bactericide and sporicide concentrations of 50 and 100 mg/kg respectively. This oil also gave positive results in controlling the American foulbrood in field trials, particularly in autumn and winter, when administered in semi-solid food (honey + easter sugar, 1:1.5) at a concentration of 400 mg/kg. In particular, the action of Cinnamomun oil on disease growth was evaluated in two distinct trials using four and five nuclei, respectively, obtained from the same colony (Apis mellifera ligustica Spin) so that each of them contained an approximately equal amount of adult bees, brood, honey and pollen beside a young queen (Liendenfelser, 1968). In both experimental trials, the worker brood was also carefully examined periodically by laboratory tests (Lloyd, 1986). The results showed that during autumn and winter, when the bees' consumption of the extra food is favoured by the environmental conditions (weather, scarcity or absence of flowers), Cinnamomun oil acts also in vivo on B larvae. However, its use in the control of American foulbrood poses several practical problems including the time and the method of administration to take full advantage of the bactericidal properties found in vitro. Ii essential oils can be used against American foulbrood, the toxicological risks and the establishment of undesirable resistance factors associated with use of chemicals would be avoided.
Activity of various essential oils against Bacillus larvae White in vitro and in apiary trials (Activité in vitro sur bacillus larvae White de plusieurs huiles essentielles et essai d'utilisation au rucher) / Floris, Ignazio; Carta, C.; Moretti, M. D. L.. - In: APIDOLOGIE. - ISSN 0044-8435. - 27:2(1996), pp. 111-119.
Activity of various essential oils against Bacillus larvae White in vitro and in apiary trials (Activité in vitro sur bacillus larvae White de plusieurs huiles essentielles et essai d'utilisation au rucher)
FLORIS, Ignazio;
1996-01-01
Abstract
The action of 21 essential oils against six strains of Bacillus larvae White, the causal agent of American foulbrood of honeybees, was studied in vitro. In a preliminary trial (table II) the effectiveness of either pure or diluted (1:5) oils was assessed by the diffusion agar method (Carta et al, 1989). The more effective ones were then tested in nutrient broth, at doses ranging from 50-400 mg/kg, to determine the minimal bactericide and sporicide concentrations. The most significant results were obtained with the oils of Citrus sinensis, Cinnamomun sp, Cuminum cyminum, Eugenia spp, Thymus vulgaris and reconstituted oil of Verbena (tables III and IV, fig 1). The same oils proved to be non-toxic for adult honeybees at the dose of 400 mg/kg. Cinnamomun oil was the most effective, with minimal bactericide and sporicide concentrations of 50 and 100 mg/kg respectively. This oil also gave positive results in controlling the American foulbrood in field trials, particularly in autumn and winter, when administered in semi-solid food (honey + easter sugar, 1:1.5) at a concentration of 400 mg/kg. In particular, the action of Cinnamomun oil on disease growth was evaluated in two distinct trials using four and five nuclei, respectively, obtained from the same colony (Apis mellifera ligustica Spin) so that each of them contained an approximately equal amount of adult bees, brood, honey and pollen beside a young queen (Liendenfelser, 1968). In both experimental trials, the worker brood was also carefully examined periodically by laboratory tests (Lloyd, 1986). The results showed that during autumn and winter, when the bees' consumption of the extra food is favoured by the environmental conditions (weather, scarcity or absence of flowers), Cinnamomun oil acts also in vivo on B larvae. However, its use in the control of American foulbrood poses several practical problems including the time and the method of administration to take full advantage of the bactericidal properties found in vitro. Ii essential oils can be used against American foulbrood, the toxicological risks and the establishment of undesirable resistance factors associated with use of chemicals would be avoided.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
