Living with varroa
The experience of beekeepers in the UK dealing with varroa has changed significantly over the period since its initial discovery. For the first few years, most beekeepers found varroa relatively easy to control with a single autumn treatment, often applied quite late in the season. However, this was followed by an acute phase in which varroa became much harder to control as mite levels were unexpectedly found to increase quickly. In particular this occurred where untreated managed and feral colonies were causing mite invasion problems. Beekeepers then found that it was vital to treat quickly after the end of the honey flow in late summer and in some cases again in the spring. Many who delayed treatment or used controls that were not sufficiently effective lost their bees – up to 50% of colonies in some areas. After this phase of widespread losses, beekeepers found that varroa again became somewhat easier to control – probably because mite invasion had reduced following the loss of feral and poorly managed colonies. For a period of several years colony losses due to varroa were relatively infrequent. However, mite levels sometimes still increased requiring a swift and effective response. More recently, the development and spread of pyrethroid resistant varroa has presented beekeepers with serious and significant new challenges. Beekeepers in affected areas have again found varroa difficult to control, and some have lost their colonies to the infestation.
Mike Brown, CSL National Bee Unit
As resistance spreads, all beekeepers will have to learn and adopt new methods of monitoring and controlling the infestation in their hives. However, the experience of beekeepers overseas successfully coping with the development of resistance in their countries demonstrates that they are able to adapt to the changing circumstances to continue beekeeping as successfully as ever.
Figure 53: It is vital that honey bee colonies go into the autumn and winter with young healthy bees and low mite populations
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