Varroa jacobsoni (Oudemans) (= V. destructor) is a parasitic mite of honey bees Apis mellifera (L.), that has had a catastrophic effect on populations of managed and feral honey bee colonies, beekeepers and the beekeeping industry worldwide. Honey bee colony losses in the United States range between 40% and 80% annually. These losses are stressing the bee industry's ability to provide adequate pollination of agricultural crops. In this project we will develop digestible encapsulations filled with essential oils that when fed to the honey bees will kill or incapacitate the mites living on the backs of the bees and the same encapsulations when fed to the larvae of the colony will limit mite feeding in the reproductive cells, thereby reducing populations of the parasitic mites in the honey bee colonies. OBJECTIVES: In Phase I of this project, we demonstrated that several oils were effective in controlling the mites, now in Phase II we plan to perfect these delivery systems with the help of the USDA Bio Products Laboratory, Albany California. Our plan is to increase the mobility of the capsules so when contacted by the bees they will be moved around the colony more easily and thereby impact more mites. In the vapor phase, we intend to extend the release rate of the oils from the capsules up to the forty days, which is the time needed for an effective control of the mites emerging from the pupal cells. The following objectives outline our plan to achieve these goals: We will reformulate the delivery system to improve the release rate of the encapsulated essential oils. In doing this, we will increase contact and vapor phase efficacies by slowing the oil release rate form encapsulation within the colony and by modifying the capsule coat. We will continue to screen previously untested essential oils for their ability to control mites. Field trials of new oils will be evaluated for their bee toxicity, effect on bee behavior, in-vitro Varroa mite toxicity and effect on mite reproduction. Once formulations are perfected we will be testing the product under field conditions in geographically diverse areas of the country. APPROACH: We will select plant essential oils for their ability to control Varroa mites. Earlier research has given us a starting point for this objective. Following the selection of the essential oils we will determine the optimum concentration of essential oils to be used in the delivery system. This will be accomplished by performing palatability tests where the microencapsulated oils are mixed in a sugar carrier and offered to the bees. Consumption rates will be recorded and analyzed. In conjunction with the feeding trial, we will analyze the level of essential oil moving through the colony and ultimately arriving in adult and larval bees, to insure effective levels of essential oils are getting to the target. This analysis will be accomplished through the use of Solid Phase Micro Extraction and gas chromatographic analysis. Once we have established a recommended dosage we will determine the effects of the essential oil formulations on phoretic mite populations and mite reproduction rates. Phoretic mite populations will be determined through use of sticky boards in the honey bee colonies and reproduction rates will be determined by pulling bee pupae from cells and recording the number of reproducing mites in the cells.
