>Resistance to American foulbrood disease by honey bee colonies Apis mellifera bred for hygienic behavior
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>Marla SPIVAK*, Gary S. REUTER
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>Abstract – Honey bee colonies, selected for hygienic behavior on the basis of a freeze-killed brood assay, demonstrated resistance to American foulbrood disease. Over two summers in 1998 and 1999, 18 hygienic and 18 non-hygienic colonies containing instrumentally inseminated queens were challenged with comb sections containing spores of the bacterium Paenibacillus larvae subsp. larvae that causes the disease. The strain of bacterium was demonstrated to be resistant to oxytetracycline antibiotic. Seven (39%) hygienic colonies developed clinical symptoms of the disease but five of these recovered (had no visible symptoms) leaving two colonies (11%) with clinical symptoms. In contrast, 100% of the non-hygienic colonies that were challenged developed clinical symptoms, and only one recovered. All non-hygienic colonies had symptoms of naturally occurring chalkbrood disease (Ascosphaera apis) throughout both summers. In contrast 33% of the hygienic colonies developed clinical symptoms of chalkbrood after they were challenged with American foulbrood, but all recovered. The diseased non-hygienic colonies produced significantly less honey than the hygienic colonies.

 -- from Apidologie 32 (2001) 555–565 555 © INRA/DIB-AGIB/EDP Sciences, 2001

Comment:
Marla Spivak has been working with hygienic bees for almost ten years now, using scientific breeding techniques such as instrumental insemination. These bees are resistant to various diseases, by virtue of their excellent housekeeping instinct. But - they are not resistant or immune to the agents that cause these diseases and can succumb in a certain percent of hives. 11 percent of the hygienic hives were *unable* to prevent full blown AFB.

This compares to 100% of non-hygienic hives broke down when infected with diseased brood (only one was able to recover on its own). Doing the math, however, one could reduce AFB incidence from one hive in a hundred to one hive in a thousand. With such a low rate as this, one would scarcely have any reason to hesitate to destroy the occasional susceptible hive. Or, *where permitted*, the diseased hives could be isolated and treated.

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