Efficacy of Modified Bottom Boards to Control Varroa Mite (Varroa destructor Anderson&Trueman) in Honeybee Colonies

This study was designed to test whether hive bottom boards modified with polyvinyl chloride pipe or screen-mesh reduces number of Varroa mites in naturally infested honeybee colonies comparing to chemical control. Fifty-six colonies distributed equally between two locations each received one of four experimental treatments: Conventional solid board with/out Apistan, Screen bottom board and Tube bottom board. Results were inconsistent between apiaries. In apiary 1, colonies with Apistan and Tube bottom boards had fewer V. destructor than other treatments in spring only, but this benefit was not apparent in Apiary 2. There were no effects of modified bottom boards on honey yield, brood production, and stored pollen. We conclude that the efficacy of modified bottom boards in reducing varroa mite population in bee colonies remains uncertain due to observed differences of hygienic behavior.