Comparative field efficiency of the extracts of plant materials for controlling Varroa destructor in relation to brood development in honey bee (Apis mellifera) colonies

Plant extracts are non-chemical compounds which play a vital role in ectoparasitic mite control and are considered safe to human being and bees. In this regard, a research experiment was laid out at Honeybee Research Institute, National Agricultural Research Centre, Islamabad, Pakistan in field conditions for evaluating comparative effectiveness of ethanolic plant extracts (basil, garlic, lemon, lemongrass and thyme) at three concentrations (500, 400 and 200 ppm) to reduce varroa damaging bee colonies (Apis mellifera). Data was recorded on reduction per cent infestation of V. destructor on adult bees and brood, dead fallen varroa per colony, mean percentage of mite mortality and sealed worker brood area after four treatment applications in experimental bee colonies. Results showed that all plant extracts at 500 ppm concentrations performed better against varroa mite as compared to control. The extract of these plants were found also safe to A. mellifera. The highest (143 ± 1.20) dead fallen varrroa and the mean 82.11% mortality of mite was recorded with the extract of lemongrass after four treatments application and was found significant from all other treatments. Similarly, maximum brood area of worker (1207.4 ± 19.63 cm2) at 500 ppm concentration of lemongrass was recorded in V. destructor infested colonies. Ethanol extracts of lemongrass and thyme proved the best and can be efficiently applied against varroa to increase honey production in field conditions.