Diapause, a strategy to endure unfavourable conditions (e.g. cold winters) is commonly found in ectothermic organisms and is characterized by an arrest of development and reproduction, a reduction of metabolic rate, and an increased resistance to adversity. Diapause, in addition to adaptations for surviving low winter temperatures, significantly influences phenology, voltinism and ultimately population growth. We review the literature on diapause and overwintering behaviour of two bark beetle species that affect spruce‐dominated forests in the northern hemisphere, and describe and compare how these strategies can influence population dynamics. The European spruce bark beetle Ips typographus (L.) (Coleoptera, Curculionidae) is the most important forest pest of Norway spruce in Europe. It enters an adult reproductive diapause that might be either facultative or obligate. Obligate diapausing beetles are considered strictly univoltine, entering this dormancy type regardless of environmental cues. Facultative diapausing individuals enter diapause induced by photoperiod, modified by temperature, thus being potentially multivoltine. The spruce beetle Dendroctonus rufipennis (Kirby) (Coleoptera: Curculionidae) infests all spruce species in its natural range in North America. A facultative prepupal diapause is averted by relatively warm temperatures, resulting in a univoltine life cycle, whereas cool temperatures induce prepupal diapause leading to a semivoltine cycle. An adult obligate diapause in D. rufipennis could limit bi‐ or multivoltinism. We discuss and compare the influence of diapause and overwinter survival on voltinism and population dynamics of these two species in a changing climate and provide an outlook on future research.

中文翻译：

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两种云杉树皮甲虫的滞育和越冬

滞育是一种忍受不利条件（例如寒冷的冬天）的策略，在变温生物中很常见，其特征是发育和繁殖停滞、代谢率降低以及对逆境的抵抗力增强。滞育除了适应冬季低温外，还显着影响物候、伏定现象和最终的人口增长。我们回顾了影响北半球以云杉为主的森林的两种树皮甲虫滞育和越冬行为的文献，并描述和比较了这些策略如何影响种群动态。欧洲云杉树皮甲虫 Ips Typgraphus (L.) (Coleoptera, Curculionidae) 是欧洲云杉最重要的森林害虫。它进入可能是兼性或专性的成人生殖滞育。专性滞育甲虫被认为是严格的单生甲虫，无论环境因素如何，都会进入这种休眠类型。兼性滞育个体进入由光周期诱导、受温度改变的滞育状态，因此具有潜在的多重性。云杉甲虫 Dendroctonus rufipennis (Kirby)（鞘翅目： Curculionidae）在北美的自然范围内侵扰所有云杉物种。相对温暖的温度可以避免兼性 prepupal 滞育，导致单伏特生命周期，而凉爽的温度会导致半伏特循环。D. rufipennis 的成年专性滞育可以限制双伏或多伏特化。