Departamentul de Apicultură şi Sericicultură, Universitatea de Ştiinţe Agricole şi Medicină Veterinară, Calea Mănăştur 3-5, Cluj-Napoca, Romania; Institut für Biologie, Molekulare Ökologie, Martin-Luther-Universität Halle-Wittenberg, Hoher Weg 4, Halle, Germany; Department of Ecology, Swedish University of Agricultural Sciences, P.O. Box 7044, Uppsala, Sweden; Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
Erler, S., Departamentul de Apicultură şi Sericicultură, Universitatea de Ştiinţe Agricole şi Medicină Veterinară, Calea Mănăştur 3-5, Cluj-Napoca, Romania, Institut für Biologie, Molekulare Ökologie, Martin-Luther-Universität Halle-Wittenberg, Hoher Weg 4, Halle, Germany; Denner, A., Departamentul de Apicultură şi Sericicultură, Universitatea de Ştiinţe Agricole şi Medicină Veterinară, Calea Mănăştur 3-5, Cluj-Napoca, Romania, Institut für Biologie, Molekulare Ökologie, Martin-Luther-Universität Halle-Wittenberg, Hoher Weg 4, Halle, Germany; Bobiş, O., Departamentul de Apicultură şi Sericicultură, Universitatea de Ştiinţe Agricole şi Medicină Veterinară, Calea Mănăştur 3-5, Cluj-Napoca, Romania; Forsgren, E., Department of Ecology, Swedish University of Agricultural Sciences, P.O. Box 7044, Uppsala, Sweden; Moritz, R.F.A., Departamentul de Apicultură şi Sericicultură, Universitatea de Ştiinţe Agricole şi Medicină Veterinară, Calea Mănăştur 3-5, Cluj-Napoca, Romania, Institut für Biologie, Molekulare Ökologie, Martin-Luther-Universität Halle-Wittenberg, Hoher Weg 4, Halle, Germany, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
Honeybee colonies offer an excellent environment for microbial pathogen development. The highest virulent, colony killing, bacterial agents are Paenibacillus larvae causing American foulbrood (AFB), and European foulbrood (EFB) associated bacteria. Besides the innate immune defense, honeybees evolved behavioral defenses to combat infections. Foraging of antimicrobial plant compounds plays a key role for this "social immunity" behavior. Secondary plant metabolites in floral nectar are known for their antimicrobial effects. Yet, these compounds are highly plant specific, and the effects on bee health will depend on the floral origin of the honey produced. As worker bees not only feed themselves, but also the larvae and other colony members, honey is a prime candidate acting as self-medication agent in honeybee colonies to prevent or decrease infections. Here, we test eight AFB and EFB bacterial strains and the growth inhibitory activity of three honey types. Using a high-throughput cell growth assay, we show that all honeys have high growth inhibitory activity and the two monofloral honeys appeared to be strain specific. The specificity of the monofloral honeys and the strong antimicrobial potential of the polyfloral honey suggest that the diversity of honeys in the honey stores of a colony may be highly adaptive for its "social immunity" against the highly diverse suite of pathogens encountered in nature. This ecological diversity may therefore operate similar to the well-known effects of host genetic variance in the arms race between host and parasite. © 2014 The Authors.