Isolated peat bog habitats and their food connections: parasitoids (Hymenoptera: Ichneumonoidea) and their lepidopteran hosts.
Central European isolated peat bog habitats (paleorefugia) harbour a unique diversity of cold adapted plants and insects. Stenotopic Lepidoptera that feed on the most typical relict bog plant Vaccinium uliginosum were extensively parasitized by families Braconidae and Ichneumonidae. Contrary to their highly specific hosts, all associated parasitoids do not seem to be selective. The most conservationally important peat bog tyrphobiontic fauna of Lepidoptera (e.g. Colias palaeno or Anarta cordigera as model examples) is always connected with generalist-parasitoids. In a disturbed peat bog and under impact of biological invasions, the penetration of alien biota (including insects) is obvious. An example is a weedy plant Frangula alnus, its obligatorily associated 'weedy' butterfly Gonepteryx rhamni, and two highly host specialized but habitat-generalist parasitoids of the genus Cotesia. Such food chains seem to be characteristic of peat bog disturbance. Host specificity of parasitoids is typical for widely distributed, easy available and abundant hosts, but paleorefugial, local and rare host-Lepidoptera seem to be associated with parasitoids of relatively wide ecological amplitude.