The field efficacy of Lepidium latifolium and Zataria multiflora methanolic extracts against Varroa destructor.

Varroa destructor is the most serious pest of honeybee (Apis mellifera), causing high economic losses in the beekeeping industry worldwide. The intensive utilization of many chemical substances against the mites resulted in resistance development. One of the applicable and alternative treatments being used for their control is plant-derived products (PDSS). The aim of this study was to evaluate the acaricidal activity of Lepidium latifolium and Zataria multiflora leaf extracts on V. destructor in field conditions. Four different concentrations (100, 200, 400, and 500 ppm) of the methanolic extracts were sprayed to treat each colony. The efficacy and side effects on adult bees were compared to Apistan chemical strips (ACSS). The acaricidal activity was the highest (100%) for L. latifolium extract at 500 ppm after 12 days and 86.26% for Z. multiflora. The infestation rate was decreased to 0.0% with L. latifolium and to 13.74% with Z. multiflora. The highest reduction was observed with L. latifolium followed by Z. multiflora extract at 500 ppm concentration. Both of the extracts showed negligible effect on bees, and it can be concluded that these PDSS as biodegradable agents could be used for V. destructor control in honeybee colonies.