The development of HopGuard® as a winter treatment against Varroa destructor in colonies of Apis mellifera

The development of new veterinary medicinal products to control Varroa destructor is very important for the successful management of honey bee colonies. We tested natural plant compounds (hop acids) as active ingredients for a new veterinary drug for Varroa control. Tolerability of bees and efficacy against mites was tested in the laboratory and in the field. In laboratory tests, hop beta acids were proven to be safe for bees (5 % mortality) and effective against mites (93.3 % mortality); there is a six-fold safety margin for bees after individual dermal application compared to the lowest dosage highly toxic to mites. In a clinical study, these results were confirmed: bee colonies tolerated the treatment (<10 % mortality), while most of the mites were killed (efficacy up to 88 %). The treatment did not affect the adult bee population and winter survival of colonies.