@article{DrescherKleinSchmittetal.2019,
  author    = {Drescher, Nora and Klein, Alexandra-Maria and Schmitt, Thomas and Leonhardt, Sara Diana},
  title     = {A clue on bee glue: New insight into the sources and factors driving resin intake in honeybees (Apis mellifera)},
  series = {PLoS ONE},
  volume    = {14},
  journal   = {PLoS ONE},
  number    = {2},
  doi       = {10.1371/journal.pone.0210594},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-200935},
  pages     = {e0210594},
  year      = {2019},
  abstract  = {Honeybees (Apis mellifera) are threatened by numerous pathogens and parasites. To prevent infections they apply cooperative behavioral defenses, such as allo-grooming and hygiene, or they use antimicrobial plant resin. Resin is a chemically complex and highly variable mixture of many bioactive compounds. Bees collect the sticky material from different plant species and use it for nest construction and protection. Despite its importance for colony health, comparatively little is known about the precise origins and variability in resin spectra collected by honeybees. To identify the botanical resin sources of A. mellifera in Western Europe we chemically compared resin loads of individual foragers and tree resins. We further examined the resin intake of 25 colonies from five different apiaries to assess the effect of location on variation in the spectra of collected resin. Across all colonies and apiaries, seven distinct resin types were categorized according to their color and chemical composition. Matches between bee-collected resin and tree resin indicated that bees used poplar (Populus balsamifera, P. x canadensis), birch (Betula alba), horse chestnut (Aesculus hippocastanum) and coniferous trees (either Picea abies or Pinus sylvestris) as resin sources. Our data reveal that honeybees collect a comparatively broad and variable spectrum of resin sources, thus assuring protection against a variety of antagonists sensitive to different resins and/or compounds. We further unravel distinct preferences for specific resins and resin chemotypes, indicating that honeybees selectively search for bioactive resin compounds.},
  language  = {en}
}
@article{DrescherKleinNeumannetal.2017,
  author    = {Drescher, Nora and Klein, Alexandra-Maria and Neumann, Peter and Ya{\~n}ez, Orlando and Leonhardt, Sara D.},
  title     = {Inside Honeybee Hives: Impact of Natural Propolis on the Ectoparasitic Mite Varroa destructor and Viruses},
  series = {Insects},
  volume    = {8},
  journal   = {Insects},
  number    = {1},
  doi       = {10.3390/insects8010015},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-171164},
  pages     = {15},
  year      = {2017},
  abstract  = {Social immunity is a key factor for honeybee health, including behavioral defense strategies such as the collective use of antimicrobial plant resins (propolis). While laboratory data repeatedly show significant propolis effects, field data are scarce, especially at the colony level. Here, we investigated whether propolis, as naturally deposited in the nests, can protect honeybees against ectoparasitic mites Varroa destructor and associated viruses, which are currently considered the most serious biological threat to European honeybee subspecies, Apis mellifera, globally. Propolis intake of 10 field colonies was manipulated by either reducing or adding freshly collected propolis. Mite infestations, titers of deformed wing virus (DWV) and sacbrood virus (SBV), resin intake, as well as colony strength were recorded monthly from July to September 2013. We additionally examined the effect of raw propolis volatiles on mite survival in laboratory assays. Our results showed no significant effects of adding or removing propolis on mite survival and infestation levels. However, in relation to V. destructor, DWV titers increased significantly less in colonies with added propolis than in propolis-removed colonies, whereas SBV titers were similar. Colonies with added propolis were also significantly stronger than propolis-removed colonies. These findings indicate that propolis may interfere with the dynamics of V. destructor-transmitted viruses, thereby further emphasizing the importance of propolis for honeybee health.},
  language  = {en}
}