Field trial and prototype optimization of a new agent against the varroa mite, a parasite of honey bees

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The mite Varroa destructor is a noxious parasite of honey bees (Apis mellifera) around the world. In Canada, varroa infestation is the main cause of winter colony losses, which curtail spring pollination of crops and honey production. This causes significant losses in income to beekeepers and presents large colony replacement costs early in the year. The way to minimize winter losses of colonies is to treat them in the fall, when varroa mite populations bloom. Beekeepers have only a limited set of acaricides for this purpose, and some of these products are fading from the market because the mites have developed resistance. We have discovered a new, highly active acaricidal compound, which was successfully tested in two locations in Canada during the fall of 2019. The compound paralyzes mites selectively, causing them to drop from the bees and eventually die. The compound has a fumigant effect, also curtailing mite reproduction inside of brood cells. The compound does not leave detectable residues in the hive and does not harm the bees, unlike some of the currently used (and fading) acaricides. In this grant application we propose to develop a new release device for the active compound we have found and to field test the prototype devices in three locations in Canada. The field test will comprise a negative control (the empty devices), the treatment (with our new acaricide) and a positive control (with a natural acaricide). The latter is essential for the implementation of integrated pest management (IPM) in parallel with the development of our new acaricide. IPM in varroa management consists of rotation of different acaricidal treatments, along with biotechnical control measures that keep mite reproduction low during the spring and summer. IPM strategies prevent or delay onset of resistance, so beekeepers will have varroa management tools for many decades, until mite resistant bees are bred and beyond. Data from the proposed field trials will be essential for the continuation in part of the patent for the new acaricide, which has been filed, and for the future registration of the compound. This, in turn, will ease the creation of a company in Canada that will license the technology.