title: Overwintering of the boreal butterfly Colias palaeno in central Europe.
abstract: BACKGROUND
  Colias palaeno (Linnaeus, 1761) (Lepidoptera: Pieridae) is a butterfly with boreal distribution with declining populations in peat bogs and subalpine habitats in Central Europe.
  
  
  OBJECTIVE
  We investigated the cold tolerance of overwintering caterpillars from one mountain population from Czech Republic (960m a.s.l.) and one alpine population from Italy (2000m a.s.l.).
  
  
  METHODS
  We measured supercooling point (SCP), lower lethal temperature (LLT) and content of cryoprotectants.
  
  
  RESULTS
  The caterpillars were freeze-avoiding, with lower LLT close to their very low SCP (-25 to -27 degree C). The mountain population accumulated high concentrations of glycerol (5% fresh mass) and sugars (trehalose 0.8%, glucose 0.2%), while the Italian alpine population only moderate amounts of glycerol (0.3%) and sugars (trehalose 0.5%, glucose 0.3%) without effect on their cold hardiness. Larvae that overwintered at +5 degree C had a lower body mass than those overwintering in natural conditions, indicating a metabolic weight loss, but both groups survived equally well.
  
  
  CONCLUSIONS
  We hypothesize that the high concentration of glycerol contributes to the high desiccation tolerance.
authors.affiliation: Faculty of Science, University of South Bohemia, Ceske Budejovice, Czech Republic.
authors.forename: P
authors.initials: P
authors.lastname: Vrba
authors.affiliation: Buro Geyer und Dolek, Worthsee, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Dolek
authors.affiliation: Faculty of Science, University of South Bohemia; Institute of Entomology, Biology Centre, Academy of Sciences of the Czech Republic, Ceske Budejovice, Czech Republic. nedved@prf.jcu.cz.
authors.forename: O
authors.initials: O
authors.lastname: Nedved
authors.affiliation: Institute of Entomology, Biology Centre, Academy of Sciences of the Czech Republic, Ceske Budejovice, Czech Republic.
authors.forename: H
authors.initials: H
authors.lastname: Zahradnickova
authors.affiliation: Department of Life Science and System Biology, University of Turin, Torino, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Cerrato
authors.affiliation: Faculty of Science, University of South Bohemia, Ceske Budejovice; Institute of Entomology, Biology Centre, Academy of Sciences of the Czech Republic, Ceske Budejovice, Czech Republic.
authors.forename: M
authors.initials: M
authors.lastname: Konvicka
mesh_terms: D000064:Acclimatization; D000818:Animals; D002080:Butterflies / Q000502:physiology*; D003080:Cold Temperature; D003451:Cryoprotective Agents / Q000378:metabolism; D017753:Ecosystem; D005060:Europe; D005615:Freezing; D005947:Glucose / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D007814:Larva / Q000502:physiology; D014199:Trehalose / Q000378:metabolism
chemical_list: D003451:Cryoprotective Agents; D014199:Trehalose; D005947:Glucose; D005990:Glycerol