Institute of Arctic Biology, University of Alaska, Fairbanks, AK 99775, USA.
J Exp Biol. 2010 Feb 1;213(3):502-9. doi: 10.1242/jeb.035758.
Larvae of the freeze-avoiding beetle Cucujus clavipes puniceus (Coleoptera: Cucujidae) in Alaska have mean supercooling points in winter of -35 to -42 degrees C, with the lowest supercooling point recorded for an individual of -58 degrees C. We previously noted that some larvae did not freeze when cooled to -80 degrees 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 degrees C and can avoid freezing to at least -150 degrees 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 degrees 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(-1) dry mass and concomitant increases in glycerol concentrations (4-6 mol l(-1)) and thermal hysteresis. Finally, we provide direct evidence that Cucujus from Wiseman, Alaska, survive temperatures to -100 degrees C.
在阿拉斯加，避冻甲虫 Cucujus clavipes puniceus（鞘翅目： Cucujidae）的幼虫在冬季的过冷却点为-35 至-42°C，记录到的最低过冷却点为-58°C。我们之前注意到，当冷却到-80°C 时，有些幼虫不会冻结，我们推测这些幼虫发生了玻璃化转变。在这里，我们通过差示扫描量热法提供证据表明，C. c. puniceus 幼虫在<-58°C 的温度下转变为玻璃态，并能避免至少-150°C 的冻结。这一新颖的发现将玻璃化转变添加到昆虫越冬策略列表中。当在倒下的树木的树皮下越冬时，C. c. puniceus 幼虫的微生境因积雪覆盖低而没有隔热时，可能会经历约-40°C（更低）的环境温度。冬季温度下降与夏季接近 2.0mg mg(-1)干重的高水平的身体水分流失有关，同时甘油浓度（4-6 mol l(-1))和热滞也会增加。最后，我们提供了直接证据表明，来自阿拉斯加 Wiseman 的 Cucujus 能够在-100°C 的温度下存活。
