2007 Annual Report 1a.Objectives (from AD-416) 1. Reformulate the delivery system to improve release rate. 2. Field trial to assess new formulation. 3. Gas Chromatograph analysis on treated colonies. 1b.Approach (from AD-416) Essential oils have shown to be effective in controlling Varroa mite. In order to achieve a better effect when applying the oils to the colony a new delivery system will be developed. Documents Trust with Almond Board of CA. Log 28814.) 3.Progress Report This report serves to document research conducted under a Trust Agreement between ARS and the Almond Board of California. Additional details of research can be found in the report for the parent project 5342-21000-014-00D, Improving Crop Pollination Rates by Increasing Colony Populations and Defining Pollination Mechanisms. In FY 2007, we selected three oils (thymol, origanum and clove) for vaporization based on their toxicity to Varroa. The smoker used to vaporize the oils produced consistent amounts of essential oil in the vapor phase. We conducted toxicity trials with Varroa and determined that 3% active ingredient (AI) resulted in mite mortality. At 3% AI, there were higher levels of mite mortality (as measured by mite drop on to sticky boards) for all oils after treatment compared with before. We tested 5%AI and found that bee mortality was unaffected. We currently are testing higher levels of AI on mite mortality in colonies. Progress on this project was monitored by annual reports to the Almond Board and presentations at the Annual Meeting of the Almond Board.