Regional variation in composition and antimicrobial activity of US propolis against Paenibacillus larvae and Ascosphaera apis

• Published in: Journal of invertebrate pathology 2015-01, Vol.124, p.44-50
• Main Authors: Wilson, M.B., Brinkman, D., Spivak, M., Gardner, G., Cohen, J.D.
• Format: Article
• Language: English
• Subjects: Animals; Anti-Infective Agents - pharmacology; Apis mellifera; Ascomycota - drug effects; Ascomycota - physiology; Ascosphaera apis; Bees - microbiology; Geography; Honey bees; Host-Pathogen Interactions - drug effects; Larva - drug effects; Larva - physiology; Microbial Sensitivity Tests; Paenibacillus - drug effects; Paenibacillus - physiology; Paenibacillus larvae; Propolis; Propolis - pharmacology; Resin
• ISSN: 0022-2011; 1096-0805
• DOI: 10.1016/j.jip.2014.10.005

•Diverse propolis samples inhibited the growth of a fungal and bacterial bee pathogen.•Differential activity was observed both among samples and between pathogens.•Antimicrobial activity was not likely due to previously reported compounds.•US propolis from botanically diverse regions had distinct compositions.•Regions that may harbor novel botanical sources of propolis were determined. Propolis is a substance derived from antimicrobial plant resins that honey bees use in the construction of their nests. Propolis use in the hive is an important component of honey bee social immunity and confers a number of positive physiological benefits to bees. The benefits that bees derive from resins are mostly due to their antimicrobial properties, but it is unknown how the diversity of antimicrobial activities among resins might impact bee health. In our previous work, we found that resins from different North American Populus spp. differed in their ability to inhibit in vitro growth of the bee bacterial pathogen Paenibacillus larvae. The goal of our current work was to characterize the antimicrobial activity of propolis from 12 climatically diverse regions across the US against the bee pathogens P. larvae and Ascosphaeraapis and compare the metabolite profiles among those samples using LC–MS-based metabolomic methods. Samples differed greatly in their ability to inhibit both bacterial and fungal growth in vitro, but propolis from Nevada, Texas, and California displayed high activity against both pathogens. Interestingly, propolis from Georgia, New York, Louisiana, and Minnesota were active against A. apis, but not very active against P. larvae. Metabolomic analysis of regional propolis samples revealed that each sample was compositionally distinct, and LC–FTMS profiles from each sample contained a unique number of shared and exclusive peaks. Propolis from Aspen, CO, Tuscon, AZ, and Raleigh, NC, contained relatively large numbers of exclusive peaks, which may indicate that these samples originated from relatively unique botanical sources. This is the first study to characterize how the diversity of bee preferred resinous plants in the US may affect bee health, and could guide future studies on the therapeutic potential of propolis for bees.