Recruitment, survival, and parasitism of monarch butterflies (Danaus plexippus) in milkweed gardens and conservation areas
Recruitment, survival, and parasitism of monarch butterflies (Danaus plexippus) in milkweed gardens and conservation areas
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DOI：
10.1007/s10841-018-0102-8
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发表时间：
2019-04-01
影响因子：
1.9
通讯作者：
McCarty, John P.
中科院分区：
文献类型：
--
作者：
Geest, Emily A.;Wolfenbarger, L. LaReesa;McCarty, John P.
帝王蝶(Danaus Plexippus)的数量正在下降，环保人士鼓励在城市和郊区景观中种植乳草花园，以帮助抵消整个繁殖范围内栖息地的损失。作为一种保护策略，花园的有效性取决于它们吸引产卵成虫的能力以及帝王幼虫在这些花园中的存活。幼虫容易受到各种捕食者的影响，也容易受到寄生在花园中的速蝇和原生动物寄生虫的影响，这些寄生虫会造成致命或亚致命的影响，但这些风险在花园中的严重程度尚不清楚。我们将传统保护区的卵子丰度和幼虫存活率与种植马利筋以吸引帝王的花园进行了比较。此外，我们收集了晚龄幼虫并在实验室饲养，以比较帝王花园和保护区之间的寄生率。在帝王的招募和存活方面，花园和保护地点都有很大的差异，花园和保护地点之间没有显着差异。Tachinid Fly的寄生率从2016年保护区幼虫的30%到2017年花园幼虫的55%不等，但在两类地点之间没有差异。在不到2%的幼虫中可检测到中华稻纵卷叶蜂的寄生。无论在哪一年，马利筋的密度对保护区或花园中的帝王卵数都没有影响。在保育区，乳草密度对寄生蜂的寄生没有影响，但在2016年乳草茎数量较少的花园中，乳草密度增加了寄生寄生蜂。园丁种植了多种马利筋，黑曲霉是帝王幼虫最常用的寄主植物(85%)。总体而言，我们的结果表明，乳草花园有可能为成功的帝王繁殖做出贡献。然而，不同地点之间的差异以及一些花园缺乏招聘，强调了这一潜在贡献的实现将取决于花园的质量。
Monarch butterflies (Danaus plexippus) are suffering from declining populations and conservationists have encouraged planting milkweed gardens in urban and suburban landscapes to help offset habitat loss across the breeding range. The effectiveness of gardens as a conservation strategy depends on their ability to attract ovipositing adults and the survival of monarch larvae in these gardens. Larvae are susceptible to a variety of predators as well as to parasitism by a tachinid fly (Lespesia archippivora) and a protozoan parasite (Ophryocystis elektroscirrha) which cause lethal or sublethal effects, yet the severity of these risks in gardens is not well understood. We compared egg abundance and larval survival in traditional conservation areas to gardens that incorporated milkweed to attract monarchs. Additionally, we collected late instar larvae and reared them in the lab to compare parasitism rates between monarch gardens and conservation areas. Both gardens and conservations sites varied widely in recruitment and survival of monarchs and there were no significant differences between the garden and conservation sites. Tachinid fly parasitism ranged from 30% of larvae from conservation sites in 2016 to 55% of larvae from gardens in 2017, but did not differ between the two categories of sites. Parasitism by O. elektroscirrha was detected in fewer than 2% of larvae. The density of milkweed had no effect on the number of monarch eggs in conservation areas or gardens in either year. Milkweed density had no effect on tachinid parasitism in conservation areas but had a significant effect in gardens with lower numbers of milkweed stems increasing tachinid parasitism in 2016. Gardeners planted a variety of species of milkweed and Asclepias syriaca was the most commonly used host plant for monarch larvae (85%). Overall, our results suggest that milkweed gardens have the potential to contribute to successful monarch reproduction. However, the variation among sites and the lack of recruitment from some gardens emphasizes that the realization of this potential contribution will depend on the quality of gardens.