Consequences of host plant toxicity across monarch butterfly ontogeny: milkweed challenges from feeding to flying

北美帝王蝶数量的下降与它们在美国和墨西哥迁徙路线上的马利筋寄主植物的消失有关。这导致了国家倡议和当地爱好者的重大马利筋重新种植努力。虽然在概念上是有价值的，但这些重新种植的努力往往会使用各种马利筋物种，这些马利筋物种对黑脉金斑蝶幼虫的毒性水平可能会有很大差异。此外，尚不清楚幼虫暴露于这种不同程度的毒性如何影响存活的成年帝王蝶建立可行种群和迁移到墨西哥越冬地点的能力。利用美国国家科学基金会的资金和利用君主科学家的大规模合作网络，研究人员将通过在受控的实验室和自然环境下检查乳草-君主在整个生命历史中的相互作用来量化这种影响。除了帝王蝶外，该项目还将为栖息地恢复工作提供信息，旨在抵消其他有益昆虫的种群减少，因为大多数昆虫的幼虫饮食史对种群健康重要的成年特征的影响知之甚少。植物-昆虫相互作用的化学生态学研究主要集中在植物防御和毒性对昆虫幼虫期的直接影响上。由于昆虫幼虫往往对植物造成最大的伤害，这种关注是有意义的，但结果只有有限的信息可用于间接的，即在幼虫期之后，寄主植物毒性对昆虫种群生长和扩散重要的成虫性状的影响。拟议的工作将通过将幼虫经历的植物防御生物化学变化与成虫适应性结果联系起来，解决这一知识空白。使用标志性的帝王蝶作为焦点物种，pi旨在量化在实验室和自然环境下，十种马利筋物种（即君主寄主植物）的毒性性状变化如何影响幼虫生长，成虫繁殖力和迁徙能力。为了实现这一目标，他们将采用一种综合的方法，结合化学生态学、有机体能量学、生物力学等最先进的方法，并利用公民科学驱动的合作，与位于帝王蝶每年迁徙路线上的几个实验室合作。这项工作与焦点物种有关，因为旨在恢复适宜栖息地以对抗帝王蝶种群数量下降的重新种植工作使用了多种乳草，而没有考虑幼虫暴露于不同的乳草防御化学物质如何影响帝王蝶种群动态和迁移。与此同时，该项目将为旨在抵消其他益虫种群数量下降的科学和栖息地恢复工作提供信息，因为大多数昆虫的幼虫饮食史对成虫特征的影响尚不清楚。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The decline in North American populations of the Monarch butterfly has been linked to the loss of their milkweed host plant along US and Mexican migration routes. This has resulted in significant milkweed replanting efforts by national initiatives and local enthusiasts. While meritorious in its conception, these replanting efforts tend to use a variety of milkweed species that can vary dramatically in their level of toxicity to Monarch larvae. Moreover, it is unknown how exposure to such varying levels of toxicity as larvae may affect the ability of surviving adult Monarch butterflies to establish viable populations and migrate to Mexican overwintering sites. Using NSF funding and leveraging a large-scale collaborative network of Monarch scientists, the researchers will quantify such effects by examining milkweed-Monarch interactions throughout their life history, under both controlled laboratory- and natural settings. In addition to Monarchs, this project will generally inform habitat restoration efforts aimed at offsetting population declines in other beneficial insects, as consequences of larval dietary history for adult traits important to population health are poorly understood in most insects.Chemical ecology research on plant-insect herbivore interactions has abundantly focused on the proximate effects of plant defenses and toxicity on insect larval stages. Since insect larvae tend to cause most damage to plants, this focus makes sense, but as a result only limited information is available on indirect, i.e., beyond the larval stages, effects of host plant toxicity on adult insect traits important for population growth and dispersal. The proposed work will address this gap in knowledge by linking variation in plant defense biochemistry experienced by larvae to adult insect fitness outcomes. Using the iconic Monarch butterfly as a focal species, the PIs aim to quantify how variation in toxic traits among ten milkweed species (i.e., Monarch host plants) affect larval growth, adult fecundity and migratory ability, in laboratory and natural contexts. To achieve this aim, they will use an integrative approach that combines state-of-the-art methods in chemical ecology, organismal energetics, biomechanics, and leverage a citizen science driven collaboration with several laboratories located along the annual Monarch's migration routes. This work is pertinent to the focal species as replanting efforts aimed at restoring suitable habitat to combat Monarch population declines use multiple milkweed species without consideration for how larval exposure to varying milkweed defensive chemistry affects Monarch population dynamics and migration. In parallel, this project will generally inform science and habitat restoration efforts aimed at offsetting population declines in other beneficial insects, as consequences of larval dietary history for adult traits are poorly understood in most insects.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.