Wilson J K, Tseng A S, Potter K A, Davidowitz G, Hildebrand J G
Department of Entomology, University of Arizona, 1140 E South Campus Drive, Forbes 410, PO Box 210036, Tucson, AZ 85721.
Department of Neuroscience, University of Arizona, 1040 E 4 Street, PO Box 210077, Tucson AZ 85721.
Arthropod Plant Interact. 2018 Feb;12(1):21-29. doi: 10.1007/s11829-017-9548-y. Epub 2017 Jul 5.
Plants have evolved many defenses against insect herbivores, including numerous chemicals that can reduce herbivore growth, performance, and fitness. One group of chemicals, the tropane alkaloids, is commonly found in the nightshade family (Solanaceae) and has been thought to reduce performance and fitness in insects. We examined the effects of the tropane alkaloid scopolamine, the alkaloid constituent of , which is the most frequent host plant for the abundant and widespread insect herbivore in the southwestern United States. We exposed caterpillars of two different species to scopolamine: , which has a shared evolutionary history with and other solanceous plants, and , which does not. We showed that the addition of ecologically-realistic levels of scopolamine to both the diet and the hemolymph of these two caterpillar species ( and ) had no effect on the growth of either species. We also showed that has no behavioral preference for or against scopolamine incorporated into an artificial diet. These results are contrary to other work showing marked differences in performance for other insect species when exposed to scopolamine, and provide evidence that scopolamine might not provide the broad-spectrum herbivore resistance typically attributed to it. It also helps to clarify the coevolutionary relationship between and one of its main host plants, as well as the physiological mechanism of resistance against scopolamine.
植物已经进化出许多抵御昆虫食草动物的防御机制，包括多种能够降低食草动物生长、性能和健康状况的化学物质。其中一类化学物质——托烷生物碱，常见于茄科植物中，人们一直认为它会降低昆虫的性能和健康状况。我们研究了托烷生物碱东莨菪碱的影响，东莨菪碱是美国西南部常见且分布广泛的昆虫食草动物最常食用的宿主植物——的生物碱成分。我们将两种不同物种的毛虫暴露于东莨菪碱中：一种与以及其他茄科植物有着共同进化历史，另一种则没有。我们发现，在这两种毛虫物种（和）的食物及血淋巴中添加生态现实水平的东莨菪碱，对任何一种物种的生长都没有影响。我们还发现，对添加到人工饲料中的东莨菪碱没有行为偏好或厌恶。这些结果与其他研究结果相反，其他研究表明，其他昆虫物种在接触东莨菪碱时性能存在显著差异，这为东莨菪碱可能无法提供通常归因于它的广谱食草动物抗性提供了证据。这也有助于阐明与其主要宿主植物之一之间的协同进化关系，以及对东莨菪碱的抗性生理机制。
