Adaptation of life-history traits is an important factor for the success of insects. Voltinism is a feature that descends from several life-history traits and, given that the latter depend on the specific environment of growth, voltinism can vary between populations across latitudes or habitats. In addition, some insects, like many odonates, have developed different patterns of voltinism within the same population, due to mechanisms of cohort splitting. Calopteryx splendens (Odonata: Calopterygidae) is a widespread damselfly in Europe that has been extensively studied regarding its evolutionary ecology, but detailed studies about its voltinism are relatively scarce and confined to the central and northern areas of Europe. So we investigated the voltinism and larval development of a population of C. splendens both by captive rearing and in the field in Northern Italy, the southernmost area in which its voltinism has been studied so far. We found an earlier start of larval growth, with respect to previous studies. Additionally, the head-width of larvae of the same instar decreased with the cohort ageing. Finally, the results are consistent with a two-groups emerging pattern that may support partial semivoltinism or partial bivoltinism of C. splendens in Northern Italy.

中文翻译：

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波河谷斑翅目（蜻蜓目：斑翅目）的伏化作用和幼虫种群结构

生活史特征的适应是昆虫成功的重要因素。Voltinism 是一种源于多种生活史特征的特征，鉴于后者取决于特定的生长环境，因此 Voltinism 在不同纬度或栖息地的人群之间可能会有所不同。此外，由于群体分裂的机制，一些昆虫，像许多齿科昆虫一样，在同一种群内发展出不同的伏廷病模式。Calopteryx splendens (Odonata: Calopterygidae) 是一种广泛分布于欧洲的豆娘，其进化生态学已被广泛研究，但对其 voltinism 的详细研究相对稀少，仅限于欧洲中部和北部地区。因此，我们调查了 C. 通过圈养饲养和在意大利北部的田野中表现出色，这是迄今为止研究过伏丁虫病的最南端的地区。与以前的研究相比，我们发现幼虫生长的开始较早。此外，同龄幼虫的头宽随着群体年龄的增长而减少。最后，结果与两组新兴模式一致，该模式可能支持意大利北部 C. splendens 的部分 semivoltinism 或部分 bivoltinism。