Contrasting Supercooling Ability in Lowland and Mountain European Colias Butterflies

Abstract We report different values of supercooling points (SCP) of overwintering larvae of 4 European species belonging to the globally-distributed butterfly genus Colias. The selected species represent diverse habitat and altitude preferences, from dry and warm steppe grasslands to alpine meadows and peat bogs. The Mediterranean migrant C. crocea Geoffroy did not survive the acclimation temperature of 5°C. All 4 remaining species were freeze-susceptible. Colias palaeno (L.), a peat bogs species, showed a high degree of cold hardiness (mean SCP: −24.8°C). It was followed by the steppe grassland specialist C. alfacariensis Ribbe (−18.6°C). Alpine C. phicomone (Esper) (−13.8°C) and lowland generalist C. hyale (L.) (−14.5°C) exhibited similar high values. We argue that besides ambient temperature, the specific microclimate at overwintering sites, and continentality influencing snow cover influence the diversity of cold hardiness in Colias butterflies.