Trials of Apiguard, a thymol-based miticide. Part 1. Efficacy for control of parasitic mites and residues in honey.

A field study was conducted to test the efficacy of Apiguard, a thymol-base d gel miticide, against varroa and tracheal mites. Apiguard was delivered t o colonies in two different package designs (treatment 1 and 2) for 21 days during July. We also collected honey samples before and during treatment t o determine thymol residues. Percent efficacy against varroa was 73-82% and 68-79% for treatments 1 and 2, respectively, compared to 14-23% natural mi te mortality over the same period in untreated colonies. When a ratio of tr acheal mite prevalence in October to prevalence in pre-treatment summer pop ulations was compared between treatments, it was found that this ratio was 8.5 and 6.2 times greater in untreated colonies than in colonies treated wi th treatments 1 and 2, respectively. Although not statistically significant , honey production was reduced by 30% during the Apiguard treatment period, a result which warrants further study. After 17 days of treatment, thymol residues were 1.55 ppm (or mu g/g) in treatment 1 colonies (95% confidence interval, or C.I,, of 0.91-2.18 ppm), and 2.64 ppm in treatment 2 colonies (95% C.I. of 1.92-3.35 ppm); residues for the latter were significantly hig her. Honey collected from control colonies at both sampling periods had no detectable levels of thymol (limit of detection was < 0.03 ppm).