Deep supercooling, vitrification and limited survival to –100°C in the Alaskan beetleCucujus clavipes puniceus(Coleoptera: Cucujidae) larvae

Abstract

SUMMARYLarvae of the freeze-avoiding beetle Cucujus clavipes puniceus (Coleoptera: Cucujidae) in Alaska have mean supercooling points in winter of -35 to -42°C, with the lowest supercooling point recorded for an individual of -58°C. We previously noted that some larvae did not freeze when cooled to -80°C, and we speculated that these larvae vitrified. Here we present evidence through differential scanning calorimetry that C. c. puniceus larvae transition into a glass-like state at temperatures <-58°C and can avoid freezing to at least -150°C. This novel finding adds vitrification to the list of insect overwintering strategies. While overwintering beneath the bark of fallen trees, C. c. puniceus larvae may experience low ambient temperatures of around -40°C (and lower) when microhabitat is un-insulated because of low snow cover. Decreasing temperatures in winter are correlated with loss of body water from summer high levels near 2.0 to winter lows near 0.4mgmg ) and thermal hysteresis. Finally, we provide direct evidence that Cucujus from Wiseman, Alaska, survive temperatures to -100°C.

More complex than expected: Cold hardiness and the concentration of cryoprotectants in overwintering larvae of five Erebia butterflies (Lepidoptera: Nymphalidae)

“…A lepidopteran example of a mixed strategy might be Papilio zelicaon Lucas, 1858 (Lepidoptera: Papilionidae), in which winter-acclimated pupae partly survive and are partly killed by internal ice formation (Williams et al, 2014). Two beetle species, Dendroides canadensis Latreille, 1810 (Pyrochroidae) (Horwath & Duman, 1984) and Cucujus clavipes Fabricius, 1781 (Cucujidae) (Kukal & Duman, 1989) may adapt their cold hardiness strategies along a latitudinal gradient, or according to acclimation conditions (Sformo et al, 2010). In the case of E. aethiops, this species' range includes warm nonalpine habitats, such as piedmont forest steppes and lowland wooded savannas (Franco et al, 2006;Slamova et al, 2011), as well as mountain forests openings and grasslands (Sonderegger, 2005).…”

Molecular basis of chill resistance adaptations in poikilothermic animals

“…In addition, damage induced by chilling may be the result of oxidative stress (Storey and Storey, 2010), including the malfunction of mitochondrial respiration or the production of peroxide (Prasad et al, 1994). Injury can occur at surprisingly high temperatures, well above 0°C, as in tropical plants, insects and fish (Bale, 2002; Denlinger and Lee, 2010;Levitt, 1980), while chill-tolerant species from Palearctic climates may not experience any chilling injury, even after prolonged exposures to temperatures well below 0°C (Sformo et al, 2010). Freezing of body compartments in many species can be even more damaging but presents a quite different scenario, with the extracellular growth of ice crystals causing both mechanical disruption of tissues and a progressive increase in extracellular osmolality.…”

Conversion of the chill susceptible fruit fly larva ( Drosophila melanogaster ) to a freeze tolerant organism

“…Such lineages had to overcome selection pressures of shorter growing season, exaggerated daily temperature fluctuations, and seasonal drop of temperatures below the physiological thresholds for activity, growth, and development (7). It is now widely accepted that cold adaptation in insects is highly complex and requires adjustments at all levels of biological organization (8)(9)(10)(11)(12)(13)(14)(15)(16). Supercooling and freeze tolerance are two main strategies that help insects to cope with the risk of water freezing in a cryothermic state.…”