Süess Philip, Roberts Kevin T, Lehmann Philipp
Department of Zoology, Stockholm University, 11418 Stockholm, Sweden.
Department of Zoology, Stockholm University, 11418 Stockholm, Sweden.
J Insect Physiol. 2023 Dec;151:104585. doi: 10.1016/j.jinsphys.2023.104585. Epub 2023 Nov 17.
Insects have the capacity to significantly modify their metabolic rate according to environmental conditions and physiological requirement. Consequently, the respiratory patterns can range from continuous gas exchange (CGE) to discontinuous gas exchange (DGE). In the latter, spiracles are kept closed during much of the time, and gas exchange occurs only during short periods when spiracles are opened. While ultimate causes and benefits of DGE remain debated, it is often seen during insect diapause, a deep resting stage that insects induce to survive unfavourable environmental conditions, such as winter. The present study explores the shifts between CGE and DGE during diapause by performing long continuous respirometry measurements at multiple temperatures during key diapause stages in the green-veined white butterfly Pieris napi. The primary goal is to explore respiratory pattern as a non-invasive method to assess whether pupae are in diapause or have transitioned to post-diapause. Respiratory pattern can also provide insight into endogenous processes taking place during diapause, and the prolonged duration of diapause allows for the detailed study of the thermal dependence of the DGE pattern. Pupae change from CGE to DGE a few days after pupation, and this shift coincides with metabolic rate suppression during diapause initiation. Once in diapause, pupae maintain DGE even at elevated temperatures that significantly increase CO production. Instead of shifting respiratory pattern to CGE, pupae increase the frequency of DGE cycles. Since total CO released during a single open phase remains unchanged, our results suggest that P. napi pupae defend a maximum internal ρCO set point, even in their heavily suppressed diapause state. During post-diapause development, CO production increases as a function of development and changes to CGE during temperature conditions permissive for development. Taken together, the results show that respiratory patterns are highly regulated during diapause in P. napi and change predictably as diapause progresses.
昆虫有能力根据环境条件和生理需求显著改变其代谢率。因此，呼吸模式可以从连续气体交换（CGE）到不连续气体交换（DGE）。在后者中，气门在大部分时间保持关闭，气体交换仅在气门打开的短时间内发生。虽然DGE的最终原因和益处仍存在争议，但它在昆虫滞育期间经常出现，滞育是昆虫为了在不利的环境条件（如冬季）中生存而进入的深度静止阶段。本研究通过在绿脉菜粉蝶Pieris napi滞育关键阶段的多个温度下进行长时间连续呼吸测量，探索滞育期间CGE和DGE之间的转变。主要目标是探索呼吸模式作为一种非侵入性方法，以评估蛹是否处于滞育状态或已过渡到滞育后阶段。呼吸模式还可以深入了解滞育期间发生的内源性过程，并且滞育的延长持续时间允许对DGE模式的热依赖性进行详细研究。蛹在化蛹几天后从CGE转变为DGE，这种转变与滞育开始期间的代谢率抑制相吻合。一旦进入滞育状态，即使在显著增加CO产生的高温下，蛹仍保持DGE。蛹不是将呼吸模式转变为CGE，而是增加DGE循环的频率。由于在单个开放阶段释放的总CO保持不变，我们的结果表明，即使在其严重抑制的滞育状态下，菜粉蝶蛹也能维持最大内部ρCO设定点。在滞育后发育期间，CO产生随着发育而增加，并在允许发育的温度条件下转变为CGE。综上所述，结果表明，菜粉蝶滞育期间呼吸模式受到高度调节，并随着滞育的进展而发生可预测的变化。
