In recent years there has been a growing concern about harmful chemical residues finding there way into the wax and pollen in the hive. Beehives are exposed to these chemicals by many past and present treatments for varroa mites, as well as the bees returning to the hive carrying pollen laced with pesticides, herbicides or fungicides. It’s not known how long this contamination will last in the frames and to what extent it hinders the health of the bees. Many beekeepers are adopting the practice of yearly comb rotation, thus gradually removing the contaminated frames from the hive.
One recent survey, however, has shown that being too aggressive with comb rotation can increase the chances of winter loss by as much as ten percent.
It’s during the winter months, while working on equipment, where I find it most effective to rotate old comb out of my deeps. This is the time of year I prepare the equipment for splits that will be made the following spring. I remove old black comb and replace it with new frames of foundation. I usually switch out two frames per box. Recently I started marking the tops of the frames with the last two digits of the year to better track how old the frames are.
This past year I have read about several studies talking about the contaminates in the pollen that the bees bring back to the hive. Scientists are beginning to find a correlation between pollen laced with pesticides, fungicides and herbicides and the immune system of the bees. Two harmful effects have been observed. First, the hive is much more likely to contract a virus, especially Nosema ceranae. Second, with all these sublethal chemical residues in the hive, the life of the queen bee is shortened and her effectiveness in laying fertilized eggs throughout her life.
One recent survey cautioned when replacing old comb that you shouldn’t exceed fifty percent of the frames. For reasons that are still being investigated, beekeepers that were too aggressive in comb replacement experienced a ten percent higher winter loss. If you click on the link below I recommend you watch the four minute video. It explained the survey much more clearly than the write up. Lastly, one interesting finding in this study was that hives started from packages were less likely to survive winter than those started from a split.