Diapause is a highly advantageous strategy for winter survival for insects living in temperate environments. However, insects typically do not feed during diapause and are therefore presented with a complicated energetics problem. The fall webworm, Hyphantria cunea, overwinter as diapausing pupae, but adults of this species lose their ability to feed due to the degeneration of their mouthparts. Thus, the energy reserves stored before diapauses contribute to the survival rate and fitness of the adults after emergence. In this study, we tested the hypothesis that diapause-destined larvae of H. cunea reserve more energy by increasing feeding rate, feeding efficiency, or both, during the diapause preparation phase compared with non-diapause-destined larvae. We observed higher digestive efficiency, increased lipase and amylase activity, and lower protease activity in diapause-destined larvae compared to non-diapause-destined larvae. These differences in digestive physiology during diapause preparation lead to greater body size and mass, increased lipid and carbohydrate content, and lower soluble protein content in diapausing pupae, relative to non-diapause pupae – results consistent with our hypothesis. We conclude that diapause-destined fall webworm reserve more energy than non-diapause-destined individuals by increasing feeding efficiency, and that this increase in efficiency is at least partially driven by increased lipase and amylase activities in the midgut. This is in contrast to non-diapause-destined larvae, which likely reserve greater protein than diapause-destined larvae to help maintain their physiological function.

中文翻译：

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滞育与非滞育秋网虫（鳞翅目：牛蒡科）蛹之间可变养分积累模式的生理机制

对于生活在温带环境中的昆虫来说，滞育是一种非常有利的冬季生存策略。然而，昆虫通常在滞育期间不进食，因此面临复杂的能量学问题。秋网虫 Hyphantria cunea 以滞育蛹的形式越冬，但该物种的成虫由于口器退化而失去摄食能力。因此，滞育前储存的能量储备有助于成虫出现后的存活率和健康状况。在这项研究中，我们检验了以下假设：与非滞育目的幼虫相比，滞育准备阶段的 H. cunea 滞育目的幼虫通过增加摄食率、摄食效率或两者来储备更多能量。我们观察到更高的消化效率，增加的脂肪酶和淀粉酶活性，与非滞育目的幼虫相比，滞育目的幼虫的蛋白酶活性较低。与非滞育蛹相比，滞育准备期间消化生理学的这些差异导致滞育蛹中更大的体型和质量、增加的脂质和碳水化合物含量以及更低的可溶性蛋白质含量——结果与我们的假设一致。我们得出结论，通过提高摄食效率，滞育注定的秋季网虫比非滞育注定的个体储备更多的能量，并且这种效率的提高至少部分是由中肠中脂肪酶和淀粉酶活性的增加驱动的。这与非滞育幼虫相反，后者可能比滞育幼虫保留更多的蛋白质，以帮助维持其生理功能。