A Spring Evaluation Of Thymol Formulated In A Sucrose Dust For The Control Of Varroa destructor, a Parasite Of The Honey Bee (Apis mellifera) In Alberta, Canada

摘要

We evaluated thymol formulated in a sucrose dust, as a control for the Varroa mite (Varroa destructor) under the cool spring conditions of northern Alberta, Canada. Our study compared two different application schedules of this formulation (four applications of 30 g at 7 d intervals or two applications of 60 g at a 14 d interval, per colony) to a commercial thymol product, Apilife VAR~R, or an untreated control group receiving sucrose without thymol. The number of Varroa mites falling on adhesive bottom boards was counted for 30 d during the treatment period. Treatments were then removed, highly effective synthetic acaricide strips (amitraz) were applied and the number of residual mites was counted for an additional 12 d. Overall, the thymol treatedgroups had higher mite counts during the treatment period compared to the untreated group, while the reverse was observed during the post-treatment interval. During the treatment period counts differed significantly on only two dates. On these dates weobserved that all the thymol treatments had significantly higher counts compared to the untreated group, but only the application of 60 g of dust at the 14 d interval had similar high counts compared to Apilife VAR~R. Nonetheless, the percentage of Varroa counted during the treatment period, compared to the total counted during both the treatment and post-treatment period, was similarly high for all the thymol treatments (>94%). Our results suggest that spring treatments with thymol dust provide a goodalternative to Apilife VAR~R and that reducing the application frequency of dust from four to two applications does not reduce treatment efficacy.