Abstract Many species of conservation concern are disturbance-dependent, relying on periodic ecosystem disruptions to maintain habitat quality. Mounting evidence suggests monarch butterflies are one such organism: they can benefit from growing-season disturbance to grassland habitats in their breeding range, with regenerating stems of milkweed host plants supporting more oviposition and lower densities of arthropod predators. Here we address three questions that were raised by previous work in this system. First, we tested if survival of neonate monarch larvae is enhanced on milkweed stems that regrow after mowing disturbance. Second, we tested if disturbance affects spore densities of the parasite Ophryocystis elektroscirrha (OE) on milkweed leaves. Finally, we documented effects of disturbance on the abundance of floral resources and flower-visiting insects. We found that first-instar monarch survival over 48 h periods was 2.3–2.5 times higher on regenerating milkweed stems than on undisturbed controls. OE spores were not detected on any of the milkweed stems in our study. Disturbance reduced floral resource abundance and floral visits for 3–5 weeks, although some species that were initially suppressed bloomed later in the season with the net effect of extending the bloom period. Our results show grassland disturbance can enhance survival of immature monarchs and could be used strategically to help stabilize the eastern monarch population. More work is needed to understand how disturbance in this system affects resources for pollinators and to optimize habitat management for monarchs and the broader pollinator community.

中文翻译：

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草地扰动对一龄帝王蝶存活、花卉资源和访花昆虫的影响

摘要 许多受保护关注的物种依赖于干扰，依靠周期性的生态系统破坏来维持栖息地质量。越来越多的证据表明帝王蝶就是这样一种生物：它们可以从生长季节对其繁殖范围内草原栖息地的干扰中受益，马利筋寄主植物的再生茎支持更多的产卵和较低的节肢动物捕食者的密度。在这里，我们解决了该系统先前工作提出的三个问题。首先，我们测试了在割草干扰后再生的马利筋茎上是否提高了新生君主幼虫的存活率。其次，我们测试了干扰是否会影响马利筋叶上寄生虫 Ophryocystis elektroscirrha (OE) 的孢子密度。最后，我们记录了干扰对丰富的花卉资源和探花昆虫的影响。我们发现，再生马利筋茎的 48 小时内的一龄君主存活率比未受干扰的对照高 2.3-2.5 倍。在我们的研究中，没有在任何乳草茎上检测到 OE 孢子。干扰减少了花卉资源丰富度和花卉访问量 3-5 周，尽管一些最初受到抑制的物种在本季晚些时候开花，最终结果是延长了开花期。我们的研究结果表明，草原干扰可以提高未成熟君主的生存率，并且可以战略性地用于帮助稳定东部君主种群。