SARE Research Synopsis
Research on the efficacy of drone brood removal for the management of V. destructor in colonies of the honey bee A. mellifera L. was funded by Northeast SARE, USDA and the Organic Farming Research Foundation (Santa Cruz, CA). Experimental colonies were treated with CheckMite+ in the fall. The following spring, quantities of bees and brood were equalized, but colonies were not retreated. The brood nest of each colony consisted of 18 full-depth worker combs and 2 full-depth drone combs housed in two, 10-frame hive bodies. Each worker comb had < 12.9 cm2 of drone cells. Drone combs were kept in the second and ninth positions of the upper brood chamber.
Standard management practices were used throughout the season, including the addition of honey supers above a queen excluder. Colonies were randomly assigned to one of two groups. In the control group, drone combs remained in place throughout the season. In the treatment group, drone combs were removed on June 16, July 16, August 16 and September 16 and replaced with empty drone combs (16 June) or with drone combs removed on the previous replacement date. In the early fall, the average mite-to-bee ratio was significantly greater in the control group than in the treatment group (figure 1).
Drone brood removal did not adversely affect colony health as measured by the size of the worker population or by honey production. Fall worker populations were similar in the two groups. Honey production in treatment colonies was greater than or similar to production in control colonies. These data demonstrate that drone brood removal can serve as a valuable component in an IPM program for V. destructor and may eliminate the need for other treatments on a colony-by-colony basis.
Research on the efficacy of screen bottom boards for the management of V. destructor in colonies of the honey bee A. mellifera L. was funded by Northeast SARE, USDA and the Organic Farming Research Foundation (Santa Cruz, CA). The study extended over three years.
In the first year, 64 colonies were randomly assigned to one of two groups: a treatment group in which colonies received screen bottom boards and control group in which colonies received regular, solid bottom boards. Equal numbers of colonies from both groups were randomly assigned to four apiary sites for evaluation. In both the second and third year, 32 colonies were randomly assigned to one of two treatment groups, but colonies were kept in a single apiary each year. Mite-to-bee ratios were estimated in the early fall each year.
The average mite-to-bee ratio in the treatment group was not significantly greater than the corresponding ratio in the control group in any year (figure 2). Screen bottom boards did not adversely affect colony health as measured by the size of the worker population or by honey production. Fall worker populations were similar in the two groups. Similarly, seasonal honey production was similar in the two groups. These data demonstrate that screen bottom boards do not provide any benefit as a mite control tactic during the honey producing season.