- Animals: bees
- Education and Training: demonstration
- Pest Management: cultural control, economic threshold, integrated pest management
- Production Systems: organic agriculture
The most destructive pest of honey bees, Apis mellifera, is the varroa mite, Varroa destructor. These ectoparasitic mites feed on adult and immature bees and reproduce within cells with developing bees. Mite infestations lead to increased transmission of viruses, deformed and underweight bees, reduced honey production and, if not controlled, colony death. The loss of great numbers of colonies has resulted from varroa mite infestation. Control measures are necessary to prevent the death of honey bee colonies. Chemical treatments can leave residues in bee products, such as honey, and have led to mite resistance. A more sustainable option is the use of integrated pest management (IPM), which involves using a combination of several mite reduction techniques which can include chemical and cultural controls. Drone brood removal is a cultural control technique that may be useful as part of an IPM program. Because varroa mites prefer to reproduce in drone cells rather than worker cells, drone brood can act as a sink for varroa mites. Removing capped drone brood infested with varroa mites can be a very effective control measure (Lavagnino and Marletto, 1995; Calderone, 2005). To remove frames of drone brood, however, heavy honey supers must be removed from colonies to access the brood nest. This seriously limits the likelihood of beekeepers adopting this chemical free varroa management technique.
Project objectives from proposal:
To avoid having to lift honey supers to access the brood nest, we recently tested drone removal using a “Tower” configuration (vanEngelsdorp, et. al. (in prep)). In order to implement this system, beekeepers simply need to push adjacent colonies together and permit them to share honey supers (Figure 1) This configuration allows access to both brood chambers and facilitates easy insertion and removal of drone frames (Figure 2). One objective of this project is to quantify the reduced labor involved in implementing this technique and thus increase the likelihood of its wider adoption.
Our work has shown that the tower configuration can slow the growth of the varroa mite population, allowing beekeepers to delay fall treatments (vanEngelsdorp et al., in prep.). However, additional treatments were still necessary to prevent economic loss. In this study, we will attempt to increase the effectiveness of drone brood removal by altering the size of the brood nest. In much of the North Eastern United States, colonies are managed in the equivalent of two deep brood chambers. Each brood chamber contains 10 frames, thus colonies typically contain 20 frames. We will also look at the effect reducing brood chambers to one ten frame chamber. Honey bees naturally produce about 17% drone brood. In our previous work, the removed drone frame represented about 5% of the brood. In this study we will compare 5% drone frame removal with 10% drone brood removal (1 frame of 10).
In addition to making drone brood accessible for removal, tower colonies use a two-queen system of management. Queens are maintained in separate boxes, but honey supers are shared. This management technique is thought to increase the honey bee population, increase colony efficacy, thus freeing more bees to forage which results in increased honey yields (Winston and Mitchell, 1986). However, traditional two queen systems stack brood chambers on top of one another, making this management style impractical. In addition quantifying the effect of drone removal to controlling varroa mites, we will document honey production to see if tower colonies increases honey production.
Further, because adjacent colonies share common honey supers, they act together as one community. If a queen is lost from one colony, bees from the other colony can maintain that colony and protect the equipment from wax moths and small hive beetle. Normally-managed colonies that lose queens have their combs quickly destroyed by these pests. We will document such events.