Abstract

The endangered and declining butterfly species Colias myrmidone is sensitive to land-use changes and vulnerable in its immature stages. The requirements for its larval habitats are still largely unknown, which hinders appropriate management in protected areas. We examined the relation between the larval development of C. myrmidone and environmental variables at a Natura 2000 site in Romania. Individuals that reached higher larval stages had a higher cover of litter as well as a lower cover of forbs around their host plants than individuals that died in early larval stages or as eggs. Surviving individuals had less other host plants in their surrounding and were found on larger host plants. Surviving individuals were found further away from the tip of their hosts than individuals that were lost due to grazing. The grazing regime is of particular importance to ensure the successful development of C. myrmidone from egg to higher larval stages. There seems to be a trade-off between positions at the tip of the shoot with palatable leaves and positions further down that protect against grazing. Especially sheep grazing may cause high direct mortality. The higher amount of litter around surviving larvae indicates a better survival when the grazing pressure is very low, but still present to keep the habitat open. However, occasional heavy grazing events may reduce the cover of forbs.

Implications for insect conservation

The designation of the investigated Natura 2000 site offers a great opportunity to implement the insights on larval development of C. myrmidone into a management plan, which can support low-intensity grazing regimes preferably with cattle.

中文翻译：

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在欧洲文化景观中保护 Colias myrmidone：在罗马尼亚的 Natura 2000 场地从卵到更高幼虫阶段成功发育的要求

摘要

濒临灭绝和衰退的蝴蝶物种Colias myrmidone对土地利用变化很敏感，在其未成熟阶段很脆弱。对其幼虫栖息地的要求在很大程度上仍然未知，这阻碍了保护区的适当管理。我们研究了C. myrmidone幼虫发育之间的关系和环境变量在罗马尼亚的 Natura 2000 站点。与在幼虫早期或卵死亡的个体相比，达到较高幼虫阶段的个体具有更高的凋落物覆盖率以及较低的寄主植物周围杂物覆盖率。幸存的个体在其周围的其他寄主植物较少，并且在较大的寄主植物上被发现。与因放牧而丢失的个体相比，存活的个体被发现离宿主尖端更远。放牧制度对于确保C. myrmidone的成功开发特别重要从卵到更高的幼虫阶段。在具有可口叶子的枝条尖端位置和更下方防止放牧的位置之间似乎存在权衡。尤其是放牧绵羊可能会导致很高的直接死亡率。当放牧压力非常低时，存活幼虫周围的垫料量越多，存活率越高，但仍然存在以保持栖息地开放。然而，偶尔的重度放牧事件可能会减少杂草的覆盖。

对昆虫保护的影响

指定被调查的 Natura 2000 站点提供了一个很好的机会，可以将C. myrmidone幼虫发育的见解实施到管理计划中，该计划可以支持最好是牛的低强度放牧制度。