Lack of prolonged activity of lavender essential oils as acaricides against the poultry red mite (Dermanyssusgallinae) under laboratory conditions.

Managing the poultry red mite, Dermanyssusgallinae (De Geer) by conventional means (i.e., synthetic acaricides) has become increasingly problematic. As a possible alternative, research has identified several plant essential oils that are toxic to D. gallinae. However, essential oils are highly volatile and any acaricidal effect they exert could be short-lived in practice. This study investigated the short-lived toxicity of six lavender essential oils to D. gallinae. In sealed Petri-dishes, mites were exposed to filter papers impregnated with essential oil at a concentration of 0.14mg/cm(3). When filter papers were used immediately after impregnation, 66-90% D.gallinae mortality was observed after 24h, depending upon the essential oil used. If impregnated filter papers were left in a fume cupboard for 24h prior to use, mortality rates of D.gallinae fell to 11% or less.