School of Environmental and Forest Sciences, University of Washington, Seattle, Box 354115, Seattle, WA, 98195, USA.
Department of Entomology, Michigan State University, East Lansing, USA.
Sci Rep. 2021 Jan 14;11(1):992. doi: 10.1038/s41598-020-80413-y.
Adoption of novel host plants by herbivorous insects can require new adaptations and may entail loss of adaptation to ancestral hosts. We examined relationships between an endangered subspecies of the butterfly Euphydryas editha (Taylor's checkerspot) and three host plant species. Two of the hosts (Castilleja hispida, Castilleja levisecta) were used ancestrally while the other, Plantago lanceolata, is exotic and was adopted more recently. We measured oviposition preference, neonate preference, larval growth, and secondary chemical uptake on all three hosts. Adult females readily laid eggs on all hosts but favored Plantago and tended to avoid C. levisecta. Oviposition preference changed over time. Neonates had no preference among host species, but consistently chose bracts over leaves within both Castilleja species. Larvae developed successfully on all species and grew to similar size on all of them unless they ate only Castilleja leaves (rather than bracts) which limited their growth. Diet strongly influenced secondary chemical uptake by larvae. Larvae that ate Plantago or C. hispida leaves contained the highest concentrations of iridoid glycosides, and iridoid glycoside composition varied with host species and tissue type. Despite having largely switched to a novel exotic host and generally performing better on it, this population has retained breadth in preference and ability to use other hosts.
植食性昆虫对新的寄主植物的适应可能需要新的适应，并且可能会导致对祖先寄主的适应丧失。我们研究了濒危蝴蝶 Euphydryas editha（泰勒的棋盘蝶）亚种与其三种寄主植物之间的关系。其中两种寄主植物（Castilleja hispida、Castilleja levisecta）是祖先的，而另一种寄主植物 Plantago lanceolata 是外来的，是最近才被采用的。我们测量了所有三种寄主植物上的产卵偏好、幼虫选择、幼虫生长和次生化学吸收。成年雌性很容易在所有寄主植物上产卵，但更喜欢 Plantago，并倾向于避免 C. levisecta。产卵偏好随时间而变化。幼虫在三种寄主植物之间没有偏好，但始终选择在 Castilleja 属植物的苞片而不是叶子。幼虫在所有物种上都能成功发育，并在所有物种上生长到相似的大小，除非它们只吃 Castilleja 叶子（而不是苞片），这会限制它们的生长。饮食强烈影响幼虫对次生化学物质的吸收。吃 Plantago 或 C. hispida 叶子的幼虫含有最高浓度的环烯醚萜糖苷，并且环烯醚萜糖苷的组成随寄主植物和组织类型而变化。尽管该种群已经在很大程度上转向了一种新的外来寄主，并且通常在这种寄主上表现更好，但它仍然保持着对其他寄主的广泛偏好和利用能力。
