Drone Brood Removal — just do it

As Andrew Matheson queried in Beekeepers Quarterly Autumn 1991 during his time as Director of IBRA, why isn’t bee research taken up by beekeepers?

This is still the case today. In IBRA magazine Bee World (vol 83 no 3 2003) there is an original article about recent research into the removal of capped drone brood as an effective means of reducing the infestation of honeybee colonies with varroa, conducted at the Swiss Bee Research Centre near Berne. The results were conclusive in stating that:
1. The removal of drone brood is an efficient means of slowing the development of varroa populations.
2. It is not possible to calculate the size of the varroa population in a hive by examining the infestation rate of drone brood.
3. Varroa do not adapt themselves to this biotechnical control method. The research reminds us that even during the summer there will always be more varroa in worker cells simply because there is usually 10 times more worker brood in a normal colony than the area of drone brood.
4. This method allows the deferral of acaricide treatments until the end of summer.

Removal of drone brood has no negative effect on the development of the colony and honey production.

The research resulted in some guidelines for beekeepers:
1. Introduce a drone frame to the brood nest at the end of March/early April.
2. Insert the drone frame at the edge of the brood nest where the comb can be quickly built up and eggs laid in it.
3. Do not allow the drones to emerge as the emerging varroa will only swell the existing varroa population.

This method alone for reducing varroa during the summer will not keep varroa under control.

At least three earlier research studies showed that varroa preferred drone brood for reproduction by a ration of 8:1. I have used and advocated drone brood removal combined with the regular autumn treatments since 1993. The NBU has promoted this method of varroa control. Surprisingly I hear this simple method of control is still not part of some beekeepers’ routine inspections.

There is a need to dispose of the comb containing the larvae and the varroa. The simplest method is a solar wax extractor. The wax is new and a superb colour which, when added to all the other scraps, becomes a valuable commodity to trade. With pyrethroid resistance likely to arrive soon, drone brood removal will be a valuable technique. Perhaps beekeepers not already doing this can make it part of their New Year resolutions. It may also lead to more regular brood nest inspections and prevent the loss of a swarm.

Maurice Field
(from ‘Gwenyn Kernow’ the newsletter of Cornwall BKA, courtesy of BEES)

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