LD sub(50) and Repellent Effects of Essential Oils from Argentinian Wild Plant Species on Varroa Destructor

The repellent and acaricidal effects of some essential oils from the most typical wild plant species of northern Patagonia, Argentina, on Varroa destructor Anderson & Trueman were evaluated using a complete exposure test. Honey bees, Apis mellifera L., and mites (five specimens of each per dish) were introduced in petri dishes having different oil concentrations (from 0.1 to 25 mu l per cage). Survival of bees and mites was registered after 24, 48, and 72 h. An attraction/repellence test was performed using a wax tube impregnated with essential oil and another tube containing wax only. The lowest LD sub(50) values for mites were registered for Acantholippia seriphioides (A. Gray) Mold. (1.27 mu l per cage) and Schinus molle L. (2.65 mu l per cage) after 24 h, and for Wedelia glauca (Ortega) O. Hoffm. ex Hicken (0.59 mu l per cage) and A. seriphioides (1.09 mu l per cage) after 72 h of treatment. The oil with the highest selectivity ratio (A. mellifera LD sub(50)/V. destructor LD sub(50)) was the one extracted from S. molle (>16). Oils of Lippia junelliana (Mold.) Troncoso, Minthostachys mollis (HBK) Grieseb., and Lippia turbinata Grieseb. mixed with wax had repellent properties. None of the oils tested had attractive effects on Varroa mites.