Department of Biology, Tufts University, Medford, MA, 02155, USA.
Department of Evolution and Ecology, University of California, Davis, CA, 95616, USA.
Oecologia. 2024 Jan;204(1):95-105. doi: 10.1007/s00442-023-05490-y. Epub 2023 Dec 20.
Understanding the circumstances under which insect herbivores will adopt a novel host plant is a longstanding question in basic and applied ecology. While geographic variation in host use can arise through differences in both herbivore preference and plant characteristics, there is a tendency to attribute geographic variation in host use to regional differences in herbivore preference alone. This is especially true for herbivores specialized to one or a few plant species. We compared how geographic variation in herbivore preference and host plant origin shape regional differences in host plant use by the specialized herbivore, Euphydryas phaeton. In parts of its range, E. phaeton uses only a native host, Chelone glabra, while in others, it also uses an introduced host, Plantago lanceolata. We offered female butterflies from each region the non-native host plant sourced from both regions and compared their oviposition behavior. The non-native host was almost universally rejected by butterflies in the region where only the native plant is used. In the region where butterflies use both hosts, females accepted non-native plants from their natal region twice as often as non-native plants from the other region where they are not used. Acceptance differed substantially among individual butterflies within regions but not among plants within regions. Thus, both individual preference and regional differences in both the insect and non-native host contributed to the geographic variation in different ways. These results highlight that, in addition to herbivore preference, regional differences in perceived plant suitability may be an important driver of diet breadth.
了解昆虫食草动物在什么情况下会选择一种新的寄主植物，这是基础和应用生态学中长期存在的问题。虽然寄主植物的利用在地理上的变化可能是由于食草动物的偏好和植物特征的差异，但往往倾向于将寄主植物的地理变化归因于食草动物偏好的区域差异。对于专门以一种或几种植物为食的食草动物来说尤其如此。我们比较了食草动物偏好和寄主植物起源的地理变化如何塑造专门食草动物 Euphydryas phaeton 对寄主植物的区域差异。在其分布的某些地区，E. phaeton 仅使用一种本地寄主植物 Chelone glabra，而在其他地区，它还使用一种外来寄主植物 Plantago lanceolata。我们为每个地区的雌性蝴蝶提供了来自两个地区的非本地寄主植物，并比较了它们的产卵行为。在仅使用本地植物的地区，非本地寄主植物几乎普遍被蝴蝶拒绝。在蝴蝶同时使用两种寄主植物的地区，雌性蝴蝶从其出生地接受非本地植物的频率是接受其他地区非本地植物的两倍，而这些地区则不使用非本地植物。在各地区内，接受情况在个体蝴蝶之间存在很大差异，但在各地区内的植物之间则没有差异。因此，个体偏好和昆虫及非本地寄主植物的区域差异以不同的方式促成了地理变化。这些结果表明，除了食草动物的偏好之外，感知植物适宜性的区域差异可能是饮食广度的一个重要驱动因素。
