Chemical composition acaricidal activity and honeybee safety of essential oils from Origanum acutidens, Satureja hortensis, and Juniperus communis against Varroa destructor

Varroa destructor is a destructive ectoparasite of honeybees (Apis mellifera). This study investigates the chemical composition and bioactivity of essential oils obtained from three medicinal plants (Origanum acutidens, Satureja hortensis, and Juniperus communis). The chemical components of the essential oils were determined by Gas Chromatography-Mass Spectrometry (GC-MS). These oils were evaluated for their acaricidal, repellent, and insecticidal activities against V. destructor, as well as their lethal effects against honeybee larvae. The results revealed that the essential oils of O. acutidens (LC50: 2.18, LC90: 6.07 µL/L) and S. hortensis (LC50: 1.79, LC90: 5.77 µL/L) exhibited strong acaricidal effects, while those of J. communis (LC50: 3.75, LC90: 4.16 µL/L) exhibited moderate activity. S. hortensis showed the highest repellent effect against V. destructor (ED50: 0.44, ED90: 1.25 µL/L), followed by O. acutidens (ED50: 0.58, ED90: 4.22 µL/L) and J. communis (ED50: 0.87, ED90: 46.3 µL/L). Furthermore, the larval mortality rates remained below 5% in all treatments, indicating negligible toxicity to honeybee larvae. Overall, this study highlights for the first time the comparative acaricidal and repellent efficacy of these three essential oils under identical experimental conditions, emphasising their potential as natural and environmentally friendly alternatives for controlling V. destructor. Further research is needed to optimise application methods and evaluate long-term effects under field conditions.