@article{GisderSchuelerHorchleretal.2017,
  author    = {Gisder, Sebastian and Sch{\"u}ler, Vivian and Horchler, Lennart L. and Groth, Detlef and Genersch, Elke},
  title     = {Long-Term Temporal Trends of Nosema spp. Infection Prevalence in Northeast Germany},
  series = {Frontiers in cellular and infection microbiology},
  volume    = {7},
  journal   = {Frontiers in cellular and infection microbiology},
  publisher = {Frontiers Research Foundation},
  address   = {Lausanne},
  issn      = {2235-2988},
  doi       = {10.3389/fcimb.2017.00301},
  pages     = {14},
  year      = {2017},
  abstract  = {The Western honey bee (Apis mellifera) is widely used as commercial pollinator in worldwide agriculture and, therefore, plays an important role in global food security. Among the parasites and pathogens threatening health and survival of honey bees are two species of microsporidia, Nosema apis and Nosema ceranae. Nosema ceranae is considered an emerging pathogen of the Western honey bee. Reports on the spread of N. ceranae suggested that this presumably highly virulent species is replacing its more benign congener N. apis in the global A. mellifera population. We here present a 12 year longitudinal cohort study on the prevalence of N. apis and N. ceranae in Northeast Germany. Between 2005 and 2016, a cohort of about 230 honey bee colonies originating from 23 apiaries was sampled twice a year (spring and autumn) resulting in a total of 5,600 bee samples which were subjected to microscopic and molecular analysis for determining the presence of infections with N. apis or/and N. ceranae. Throughout the entire study period, both N. apis- and N. ceranae-infections could be diagnosed within the cohort. Logistic regression analysis of the prevalence data demonstrated a significant increase of N. ceranae-infections over the last 12 years, both in autumn (reflecting the development during the summer) and in spring (reflecting the development over winter) samples. Cell culture experiments confirmed that N. ceranae has a higher proliferative potential than N. apis at 27. and 33 degrees C potentially explaining the increase in N. ceranae prevalence during summer. In autumn, characterized by generally low infection prevalence, this increase was accompanied by a significant decrease in N. apis- infection prevalence. In contrast, in spring, the season with a higher prevalence of infection, no significant decrease of N. apis infections despite a significant increase in N. ceranae infections could be observed. Therefore, our data do not support a general advantage of N. ceranae over N. apis and an overall replacement of N. apis by N. ceranae in the studied honey bee population.},
  language  = {en}
}
@article{ScheinerTotevaReimetal.2014,
  author    = {Scheiner, Ricarda and Toteva, Anna and Reim, Tina and Sovik, Eirik and Barron, Andrew B.},
  title     = {Differences in the phototaxis of pollen and nectar foraging honey bees are related to their octopamine brain titers},
  series = {Frontiers in physiology},
  volume    = {5},
  journal   = {Frontiers in physiology},
  publisher = {Frontiers Research Foundation},
  address   = {Lausanne},
  issn      = {1664-042X},
  doi       = {10.3389/fphys.2014.00116},
  pages     = {8},
  year      = {2014},
  abstract  = {The biogenic amine octopamine is an important neuromodulator, neurohormone and neurotransmitter in insects. We here investigate the role of octopamine signaling in honey bee phototaxis. Our results show that groups of bees differ naturally in their phototaxis. Pollen forgers display a lower light responsiveness than nectar foragers. The lower phototaxis of pollen foragers coincides with higher octopamine titers in the optic lobes but is independent of octopamine receptor gene expression. Increasing octopamine brain titers reduces responsiveness to light, while tyramine application enhances phototaxis. These findings suggest an involvement of octopamine signaling in honey bee phototaxis and possibly division of labor, which is hypothesized to be based on individual differences in sensory responsiveness.},
  language  = {en}
}
@article{BehrendsScheiner2012,
  author    = {Behrends, Andreas and Scheiner, Ricarda},
  title     = {Octopamine improves learning in newly emerged bees but not in old foragers},
  series = {JOURNAL OF EXPERIMENTAL BIOLOGY},
  volume    = {215},
  journal   = {JOURNAL OF EXPERIMENTAL BIOLOGY},
  number    = {7},
  publisher = {COMPANY OF BIOLOGISTS LTD},
  address   = {CAMBRIDGE},
  issn      = {0022-0949},
  doi       = {10.1242/jeb.063297},
  pages     = {1076 -- 1083},
  year      = {2012},
  abstract  = {Honey bees (Apis mellifera) are well known for their excellent learning abilities. Although most age groups learn quickly to associate an odor with a sucrose reward, newly emerged bees and old foragers often perform poorly. For a long time, the reason for the poor learning performance of these age groups was unclear. We show that reduced sensitivity for sucrose is the cause for poor associative learning in newly emerged bees but not in old foragers. By increasing the sensitivity for sucrose through octopamine, we selectively improved the learning performance of insensitive newly emerged bees. Interestingly, the learning performance of foragers experiencing the same treatment remained low, despite the observed increase in sensitivity for the reward. We thus demonstrate that increasing sensitivity for the reward can improve the associative learning performance of bees when they are young but not when they had foraged for a long time. Importantly, octopamine can have very different effects on bees, depending on their initial sensory sensitivity. These differential effects of octopamine have important consequences for interpreting the action of biogenic amines on insect behavior.},
  language  = {en}
}