Greetings
Four years ago I published a series of articles in the ABJ about "Keeping Bees without Chemicals". This is what everyone wants. I used information from first hand experience, friends, research and anecdotes from Bee-L to make a case that chemical free beekeeping is feasible. However, it did not work for me. The reasons are complex and have to do with the fact that we do not keep bees in isolation, the population of honey bees is cosmopolitan and we often share our neighbors problems. I have not given up and continue to collect information from all quarters. The issues are well summarized here

> Natural selection ... may lead to unexpected results concerning the performance of the colony and beekeepers have to realize that their wish list (strong colonies with gentle bees producing high honey yields) may no longer be fulfilled by bees resulting from such selection.

> A basic and important question is whether the observed stable host–parasite relationships are more an effect of the host or the parasite. Without doubt, selection acts on both and according to the established hypothesis of the development of host–parasite relationships depends mainly on the means of transmission. Generally, pathogens that rely mainly on horizontal transmission are likely to develop more virulent host–parasite relationships, while vertical transmission should favor more benign relationships (Fries and Camazine, 2001).

> We can summarize that natural selection towards Varroa tolerance in the honey bee is possible and in some cases a partial tolerance has already been confirmed. Unfortunately, none of the described cases show a clear correlation of tolerance to a specific host factor. Therefore, it remains unclear whether the study of these tolerant populations will be helpful for the determination of tolerance factors.

> However, we must also state that we have not achieved the original aim to get rid of the parasite or at least to solve the problems related to Varroosis. There is neither a Varroa treatment available which fulfills all the criteria "safe, effective and easy to apply" nor a honey bee which is sustainably tolerant to Varroosis under temperate climatic conditions. Rather, we now face new problems with secondary diseases and damage in honey bee colonies caused by synergistic effects of Varroosis plus other pathogens or environmental factors.

Biology and control of Varroa destructor
Peter Rosenkranz, Pia Aumeier, Bettina Ziegelmann
Journal of Invertebrate Pathology 103 (2010) S96–S119

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