Rapid cold hardening protects against sublethal freezing injury in an Antarctic insect

Rapid cold hardening (RCH) is a type of beneficial phenotypic plasticity that occurs on extremely short time scales (minutes to hours) to enhance insects' ability to cope with cold snaps and diurnal temperature fluctuations. RCH has a well-established role in extending lower lethal limits, but its ability to prevent sublethal cold injury has received less attention. The Antarctic midge, Belgica antarctica is Antarctica's only endemic insect and has a well-studied RCH response that extends freeze tolerance in laboratory conditions. However, the discriminating temperatures used in previous studies of RCH are far below those ever experienced in the field. Here, we tested the hypothesis that RCH protects against nonlethal freezing injury. Larvae of B. antarctica were exposed to either control (2&[deg]C), direct freezing (-9&[deg]C for 24 h), or RCH (-5&[deg]C for 2 h followed by -9&[deg]C for 24 h). All larvae survived both freezing treatments, but RCH larvae recovered more ...

快速冷驯化（rapid cold hardening, RCH）是一类发生于极短时间尺度（数分钟至数小时）的有益表型可塑性（phenotypic plasticity），可增强昆虫应对寒潮与昼夜温度波动的能力。目前学界已明确其在提升低温致死下限方面的作用，但它对亚致死冷损伤（sublethal cold injury）的预防效果却较少受到关注。
南极摇蚊（Belgica antarctica）是南极洲唯一的特有昆虫，其快速冷驯化响应已被广泛研究，该响应可在实验室条件下提升其冻耐受能力（freeze tolerance）。不过，以往快速冷驯化研究中所使用的实验处理温度，远低于该物种在野外实际经历的温度范围。
本研究检验了“快速冷驯化可抵御非致死冻害”这一假说。
实验将南极摇蚊幼虫分为三组：对照组（2℃）、直接冻害组（-9℃处理24小时）以及快速冷驯化组（先在-5℃处理2小时，随后置于-9℃继续处理24小时）。
两组冻害处理组的幼虫均存活，但经RCH处理的幼虫恢复情况更优……