Foulbrood Diseases of Honey Bees—From Science to Practice

Bacterial diseases are quite common in animals, and in most cases one animal is host to many bacterial pathogens. However, only two bacteria are known to cause disease in honey bee and these two bacteria are only pathogenic to honey bee larvae. One of these bacterial brood pathogens is the bacterium Paenibacillus larvae (P. larvae), causing American Foulbrood (AFB). AFB is the most serious honey bee brood disease because AFB is not only able to kill infected larvae but may also lead to the death of entire colonies. AFB is highly contagious and can spread quite fast within an apiary and between apiaries. Therefore, AFB is a notifiable epizootic in many countries and mandatory control measures often include the culling of diseased colonies or even of all colonies of an affected apiary. So far, no satisfactory strategies which can prevent or cure the disease are available. To change this situation, a better understanding of the pathogenesis of AFB is urgently needed. In the following chapter, the current state of AFB research is presented. The two P. larvae genotypes ERIC I and ERIC II are introduced, and their relevance for both research and practice is explained. Several P. larvae factors necessary for pathogenesis and virulence are described together with the methods used for their discovery and evaluation. A model on the interaction between P. larvae and larvae during pathogenesis is presented integrating all the novel data. Special emphasis has been put into outlining the practical implications of the newly generated knowledge.