Browsing by Subject "Propolis"

Now showing 1 - 3 of 3
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    3-Acyl dihydroflavonols from poplar resins collected by honey bees are active against the bee pathogens Paenibacillus larvae and Ascosphaera apis
    (Elsevier, 2017) Wilson, Michael B.; Pawlus, Alison D.; Brinkman, Doug; Gardner, Gary; Hegeman, Adrian D.; Spivak, Marla; Cohen, Jerry D.
    Honey bees, Apis mellifera, collect antimicrobial plant resins from the environment and deposit them in their nests as propolis. This behavior is of practical concern to beekeepers since the presence of propolis in the hive has a variety of benefits, including the suppression of disease symptoms. To connect the benefits that bees derive from propolis with particular resinous plants, we determined the identity and botanical origin of propolis compounds active against bee pathogens using bioassay-guided fractionation against the bacterium Paenibacillus larvae, the causative agent of American foulbrood. Eleven dihydro-flavonols were isolated from propolis collected in Fallon, NV, including pinobanksin-3-octanoate. This hitherto unknown derivative and five other 3-acyl-dihydroflavonols showed inhibitory activity against both P. larvae (IC50 ¼ 17e68 mM) and Ascosphaera apis (IC50 ¼ 8e23 mM), the fungal agent of chalkbrood. A structure-activity relationship between acyl group size and antimicrobial activity was found, with longer acyl groups increasing activity against P. larvae and shorter acyl groups increasing activity against A. apis. Finally, it was determined that the isolated 3-acyl-dihydroflavonols originated from Populus fremontii, and further analysis showed these compounds can also be found in other North American Populus spp.
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    Colony-level immunity benefits and behavioral mechanisms of resin collection by honey bees.
    (2010-10) Simone, Michael Dominick
    The general goal of this thesis is to understand the proximate and ultimate mechanisms of resin collection and use in honey bees, Apis mellifera. While there has been significant research on bee-collected resins with respect to human health and various chemical component analyses, this thesis provides the first review and studies on the direct implications of the role of resin in regard to honey bee health, and thus, pioneers a new area of research. I also provide novel information concerning the stimuli that may be involved in the recruitment of foragers and initiation of resin foraging. Overall my thesis provides the first evidence that resin collection is a form of social immunity in honey bees and may both have direct and indirect effects on individual immunity and colony health. I have also shed new light on the behavioral mechanisms that may be mediating this behavior at both the colony level (self-medication) and individual level (assessment of tactile information). I tested original hypotheses that led to new questions and opportunities for further research that will be conducted by me and others for a long period of time.
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    Origin, composition, and role of antimicrobial plant resins collected by honey bees, Apis mellifera
    (2014-05) Wilson, Michael Bradley
    The use of plant resins in nest building by honey bees, Apis mellifera, is an oft ignored, but critical behavior to bee health. Termed `propolis' by beekeepers, deposited resins in the nest have many positive physiological effects on the colony. Honey bees are feral and abundantly managed in many regions of the United States, from the Sonoran Desert to icy Minnesota, yet a diversity of very different resinous plants exist in every environment they call home. We know very little about what resinous plants bees utilize in these different regions, or what benefits bees might derive from specific plants. It is thought that the antimicrobial properties inherent in resins, which are complex mixtures of phenolic and isoprenoid compounds, are important drivers of their derived benefits to bees. The research herein focuses on creating better methods to track resin forager behavior, and then using those methods to discover the botanical sources of bee-foraged resins, while also exploring how resins from different plants directly affect the growth of two bee pathogens, the gram-positive bacteria Paenibacillus larvae and the fungus Ascophaera apis. I found that individual resin foragers can be chemically tracked to their resinous plant targets using metabolomic methods that hold great advantages over traditional chemical analyses, and that there is much diversity in the ability of resins from different Populus spp. to inhibit the in vitro growth of P. larvae and A. apis. I go on to further explore the benefits of different resins and find that propolis from Fallon, NV was particularly active against P. larvae and A. apis out of samples from 12 different regions in the U.S. Finally, I used bioassay-guided fractionation against P. larvae to isolated several flavanone-3-alkyl esters from NV propolis that displayed very high activity (IC50 = 17 µM to 68 µM) against P. larvae and A. apis. Re-examination of data from my previous studies indicated that these compounds were strong contributors to overall anti-P. larvae activity in regional propolis samples, and that Populus spp. are likely the botanical sources of these compounds.