Biotechnical Varroa Control Methods

Two Biotechnical Varroa Control Methods

The treatment of Varroa mites has become increasingly difficult due to its ability to become resistant to miticides. Biotechnical varroa control methods do not have this drawback, and therefore, will become more important in the toolbox of the apiarists. With the support of the Investment Agriculture Foundation of BC and the Bee BC program, the Comox Valley Bee Club has delivered workshops on two main biotechnical Varroa control methods: Drone Brood Removal Method, and Varroa Trap Method.

Workshop materials:

Drone Brood Removal Method

The concept is simple: insert a frame of drone comb into a colony at the edge of the brood nest and allow the queen to fill it with drone eggs. The varroa mites will enter the cells for reproduction and after the drone frame has been capped it will be removed before the mites emerge. Drone brood cells about to be capped are magnets for Varroa mites (up to 12 times likely to enter, versus worker brood cells).

Studies show (with 2 full frames exchanged per month) that mite levels could be kept between 0-7%, which is up to 10 times less than the control colonies!

The Split Drone Frame (containing 2 half frames) allows the continued swapping (i.e. weekly) of capped drone brood without introducing (and removing) more drone cells than necessary (1 full frame for 2 supers equals 5%).

The capped half frame is frozen for at least 2 days and uncapped before inserting it again into the Split Drone Frame. The worker bees will clean out the cells and make some use of the protein. There is no negative effect on the development of the colony and honey production.

Varroa Trap Method

The varroa trap method is one of the oldest known biotechnical varroa treatments beside the removal of drone brood. It combines the concepts of the complete brood removal technique with that of a brood break. Studies of the varroa trap method have demonstrated very high efficiency in reducing the Varroa load in the colonies:

1983, 1988 Klepsch and Maul (Kirchain, Germany): description of method, evaluation of workload, efficiency 94% and 89%, no reduced honey yield.

1989, Fries and Hansen (Denmark), method in northern climate (Gotland, Sweden), efficiency 93%.

A frame cage is used to confine the queen to a trap comb, preferably an older comb since she is less inclined to lay on fresh combs. When applied two to three weeks before the end of the nectar flow no loss in honey production can be expected as the temporary decline bee of the population will occur just after that. The graph (Bee Institute of Kirchhain, Germany) shows that the mite count drastically drops during the treatment.

The queen is separated for 27 days with the aid of a frame cage made from queen excluders, whereby she can only lay eggs in the comb within the frame cage.

During this time, all bees are hatching from the remaining brood combs outside the frame cage. Every nine days, the trap comb from the frame cage will be exchanged and placed beside the frame cage. This action will be repeated three times. The varroa mites eventually only find suitable brood cells for reproduction in the trap combs inside the frame cage. The trap combs are to be removed from the hive after the cells are capped. That way it is possible to eliminate 90% of varroa mites without chemicals. The trap combs can be discarded, if old, or frozen for at least 2 days and returned to the hive after de-capping the cells. The worker bees will clean out the cells and make some use of the protein.

Instead of a 3*9 cycle, the queen can be swapped four times once every week (4*7 cycle). This 28 day variant is well suited for weekend beekeepers.

Artificial Brood Break Method

See also this semi-biotechnical method. The Artificial Brood Break Metohod.