@article{BeerHaertelHelfrichFoerster2022,
  author    = {Beer, Katharina and H{\"a}rtel, Stephan and Helfrich-F{\"o}rster, Charlotte},
  title     = {The pigment-dispersing factor neuronal network systematically grows in developing honey bees},
  series = {The Journal of Comparative Neurology},
  volume    = {530},
  journal   = {The Journal of Comparative Neurology},
  number    = {9},
  doi       = {10.1002/cne.25278},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-257300},
  pages     = {1321-1340},
  year      = {2022},
  abstract  = {The neuropeptide pigment-dispersing factor (PDF) plays a prominent role in the circadian clock of many insects including honey bees. In the honey bee brain, PDF is expressed in about 15 clock neurons per hemisphere that lie between the central brain and the optic lobes. As in other insects, the bee PDF neurons form wide arborizations in the brain, but certain differences are evident. For example, they arborize only sparsely in the accessory medulla (AME), which serves as important communication center of the circadian clock in cockroaches and flies. Furthermore, all bee PDF neurons cluster together, which makes it impossible to distinguish individual projections. Here, we investigated the developing bee PDF network and found that the first three PDF neurons arise in the third larval instar and form a dense network of varicose fibers at the base of the developing medulla that strongly resembles the AME of hemimetabolous insects. In addition, they send faint fibers toward the lateral superior protocerebrum. In last larval instar, PDF cells with larger somata appear and send fibers toward the distal medulla and the medial protocerebrum. In the dorsal part of the medulla serpentine layer, a small PDF knot evolves from which PDF fibers extend ventrally. This knot disappears during metamorphosis and the varicose arborizations in the putative AME become fainter. Instead, a new strongly stained PDF fiber hub appears in front of the lobula. Simultaneously, the number of PDF neurons increases and the PDF neuronal network in the brain gets continuously more complex.},
  language  = {en}
}
@article{BeerSteffanDewenterHaerteletal.2016,
  author    = {Beer, Katharina and Steffan-Dewenter, Ingolf and H{\"a}rtel, Stephan and Helfrich-F{\"o}rster, Charlotte},
  title     = {A new device for monitoring individual activity rhythms of honey bees reveals critical effects of the social environment on behavior},
  series = {Journal of Comparative Physiology A},
  volume    = {202},
  journal   = {Journal of Comparative Physiology A},
  number    = {8},
  doi       = {10.1007/s00359-016-1103-2},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-188030},
  pages     = {555-565},
  year      = {2016},
  abstract  = {Chronobiological studies of individual activity rhythms in social insects can be constrained by the artificial isolation of individuals from their social context. We present a new experimental set-up that simultaneously measures the temperature rhythm in a queen-less but brood raising mini colony and the walking activity rhythms of singly kept honey bees that have indirect social contact with it. Our approach enables monitoring of individual bees in the social context of a mini colony under controlled laboratory conditions. In a pilot experiment, we show that social contact with the mini colony improves the survival of monitored young individuals and affects locomotor activity patterns of young and old bees. When exposed to conflicting Zeitgebers consisting of a light-dark (LD) cycle that is phase-delayed with respect to the mini colony rhythm, rhythms of young and old bees are socially synchronized with the mini colony rhythm, whereas isolated bees synchronize to the LD cycle. We conclude that the social environment is a stronger Zeitgeber than the LD cycle and that our new experimental set-up is well suited for studying the mechanisms of social entrainment in honey bees.},
  language  = {en}
}