Inhibition of Paenibacillus larvae subsp. larvae by the essential Oils of two wild plants and their emulsifying agents.

FUSELLI, SANDRA; GENDE, LIESEL; GARCÍA DE LA ROSA, SUSANA; EGUARAS, MARTIN; FRITZ, ROSALIA

SPANISH JOURNAL OF AGRICULTURAL RESEARCH

Año: 2005 vol. 3 p. 220 - 224

1695-971X

In honey bees (Apis mellifera L.), American foulbrood (AFB) is caused by the infection of the larvae and pupae with the bacterium Paenibacillus larvae subsp. larvae. The antibacterial effects of the essential oils of wild chamomile (Tagetes minuta L.) and Andean thyme (Acantholippia seriphioides A. Gray) against different strains of P. larvae subsp. larvae were evaluated in vitro. The possible inhibitory effects of two emulsifiers of these oils (propylene glycol and soybean lecithin) were also assessed. Significant differences in antibacterial action were seen between the oils and emulsifiers (P < 0.01). Andean thyme had the strongest antibacterial effect; the minimum inhibitory and minimum bactericide concentrations were 200-250 mg l-1 and 300 mg l-1 respectively. An additional inhibitory effect was seen when propylene glycol was used as an emulsifier; no such extra effect was seen when soybean lecithin was employed.