High prevalence of Paenibacillus larvae, the pathogenic agent of American foulbrood disease, in Palestinian honey bee colonies

The spore-forming bacterium Paenibacillus larvae causes a devastating brood disease of honey bees (Apis mellifera) named American foulbrood (AFB). It occurs worldwide and can lead to the death of whole colonies. Presence and prevalence of this pathogen in Palestine were unknown. Therefore, for two consecutive years, a field survey was conducted to screen Palestinian beekeeping locations for P. larvae. Honey samples were collected from 10 colonies each of eight apiaries throughout the West Bank in spring, summer, and fall. The presence of the bacterium was identified microbiologically, via PCR and DNA sequencing. Bacterial genotypes were analysed by repetitive element-PCR fingerprinting using ERIC primers. We unexpectedly detected spores in 87.5% of the inspected apiaries, 22.3% of 130 inspected colonies contained spores. 62.1% of the colonies with spores were lost during the study period. Whereas clinical symptoms of the disease were absent, parameters like reduced brood production and or spotty brood pattern proved to be helpful but indirect indicators for the disease. The detection of P. larvae is the first record of this fatal pathogen in Palestine. The genotype ERIC I was found six apiaries, the more virulent ERIC II genotype was present in two apiaries and is the first report of ERIC genotypes in Palestine. The study emphasizes the need for immediate steps toward efficient treatment limiting the spread of this harmful bacterium within the country and in neighboring countries.