Entomological Collection, Department of Environmental Systems Science, ETH Zürich, Weinbergstrasse 56/58, Zürich, 8092, Switzerland.
Museum of Comparative Zoology, Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA, 02138, USA.
Ecol Lett. 2020 Dec;23(12):1862-1877. doi: 10.1111/ele.13581. Epub 2020 Sep 24.
Cycads are an ancient group of tropical gymnosperms that are toxic to most animals - including humans - though the larvae of many moths and butterflies (order: Lepidoptera) feed on cycads with apparent immunity. These insects belong to distinct lineages with varying degrees of specialisation and diverse feeding ecologies, presenting numerous opportunities for comparative studies of chemically mediated eco-evolutionary dynamics. This review presents the first evolutionary evaluation of cycad-feeding among Lepidoptera along with a comprehensive review of their ecology. Our analysis suggests that multiple lineages have independently colonised cycads from angiosperm hosts, yet only a few clades appear to have radiated following their transitions to cycads. Defensive traits are likely important for diversification, as many cycad specialists are warningly coloured and sequester cycad toxins. The butterfly family Lycaenidae appears to be particularly predisposed to cycad-feeding and several cycadivorous lycaenids are warningly coloured and chemically defended. Cycad-herbivore interactions provide a promising but underutilised study system for investigating plant-insect coevolution, convergent and divergent adaptations, and the multi-trophic significance of defensive traits; therefore the review ends by suggesting specific research gaps that would be fruitfully addressed in Lepidoptera and other cycad-feeding insects.
苏铁是一类古老的热带裸子植物，对大多数动物——包括人类——都有毒性，但许多蛾类和蝴蝶（鳞翅目）的幼虫却以苏铁为食，且似乎具有免疫力。这些昆虫属于不同的谱系，具有不同程度的特化和多样化的取食生态，为化学介导的生态进化动态的比较研究提供了许多机会。本综述首次对鳞翅目苏铁取食行为进行了进化评估，并对其生态学进行了全面综述。我们的分析表明，多个谱系已经从被子植物宿主中独立地殖民到苏铁中，但只有少数几个分支在向苏铁过渡后似乎发生了辐射。防御性特征可能对多样化很重要，因为许多苏铁专食者具有警告色，并隔离苏铁毒素。蝴蝶科蛱蝶科似乎特别倾向于苏铁取食，并且有几个苏铁食性蛱蝶科具有警告色和化学防御。苏铁-食草动物的相互作用为研究植物-昆虫协同进化、趋同和趋异适应以及防御性特征的多营养重要性提供了一个很有前景但未被充分利用的研究系统；因此，本综述最后提出了一些具体的研究空白，这些空白在鳞翅目和其他苏铁食性昆虫中进行研究将会很有成果。
