In vitro inhibitory actions of some essential oils on Ascosphaera apis, a fungus responsible for honey bee chalkbrood
Haïfa Boudegga, Naïma Boughalleb, Naïma Barbouche, Mohamed Habib Ben Hamouda and Mohamed El Mahjoub
Chalkbrood is a highly contagious disease of the honey bee Apis mellifera caused by the heterothallic fungus known as Ascosphaera apis. The disease appears to be most prevalent in the spring when the brood area is increasing. Certain essential oils are known for their antibacterial and antifungal properties. In this study, a number of essential oils have been shown to be particularly effective in controlling the in vitro growth of A. apis. We tested nine essential oils using two in vitro methods, a direct contact method and a confrontation method. The essential oils used were: Lavandula angustifolia; Rosmarinus officinalis; Thymus vulgaris; Salvia officinalis; Mentha x piperita; Pelargonium graveolens; Prunus dulcis; Citrus aurantium; and Olea europaea. Thyme oil produced the best results, followed by the Pelargonium oil. The remaining essential oils were shown to have limited efficacy against A. apis in this in vitro test system, but may contribute to the enhancement of biological or integrated pest management strategies in apiculture.