Rousseaux M Cecilia, Ballaré Carlos L, Scopel Ana L, Searles Peter S, Caldwell Martyn M
IFEVA, Departamento de Ecología, Facultad de Agronomía, Universidad de Buenos Aires, Av. San Martín 4453, 1417 Buenos Aires, Argentina e-mail:
Department of Rangeland Resources and the Ecology Center, Utah State University, Logan, UT 84322-5230, USA, , , , , , US.
Oecologia. 1998 Oct;116(4):528-535. doi: 10.1007/s004420050618.
We examined the effects of solar ultraviolet-B radiation (UVB) on plant-herbivore interactions in native ecosystems of the Tierra del Fuego National Park (southern Argentina), an area of the globe that is frequently under the Antarctic "ozone hole" in early spring. We found that filtering out solar UVB from the sunlight received by naturally-occurring plants of Gunnera magellanica, a creeping perennial herb, significantly increased the number of leaf lesions caused by chewing insects. Field surveys suggested that early-season herbivory was principally due to the activity of moth larvae (Lepidoptera: Noctuidae). Manipulative field experiments showed that exposure to solar UVB changes the attractiveness of G. magellanica leaf tissue to natural grazers. In a laboratory experiment, locally caught moth caterpillars tended to eat more tissue from leaves grown without UVB than from leaves exposed to natural UVB during development; however, the difference between treatments was not significant. Leaves grown under solar UVB had slightly higher N levels than leaves not exposed to UVB; no differences between UVB treatments in specific leaf mass, relative water content, and total methanol-soluble phenolics were detected. Our results show that insect herbivory in a natural ecosystem is influenced by solar UVB, and that this influence could not be predicted from crude measurements of leaf physical and chemical characteristics and a common laboratory bioassay.
我们研究了太阳紫外线B辐射（UVB）对火地岛国家公园（阿根廷南部）原生生态系统中植物与食草动物相互作用的影响，该地区在早春时节经常处于南极“臭氧洞”之下。我们发现，对匍匐多年生草本植物麦哲伦大叶草（Gunnera magellanica）的天然植株所接收的阳光进行紫外线B过滤，会显著增加咀嚼式昆虫造成的叶片损伤数量。实地调查表明，早季食草行为主要是由蛾幼虫（鳞翅目：夜蛾科）的活动引起的。控制性实地实验表明，暴露于太阳紫外线B会改变麦哲伦大叶草叶片组织对天然食草动物的吸引力。在一项实验室实验中，当地捕获的蛾幼虫倾向于食用在发育过程中未接受紫外线B照射的叶片组织，而不是接受天然紫外线B照射的叶片组织；然而，不同处理之间的差异并不显著。在太阳紫外线B照射下生长的叶片氮含量略高于未接受紫外线B照射的叶片；在特定叶质量、相对含水量和总甲醇可溶性酚类物质方面，未检测到紫外线B处理之间的差异。我们的结果表明，自然生态系统中的昆虫食草行为受到太阳紫外线B的影响，而且这种影响无法通过对叶片物理和化学特征的粗略测量以及常见的实验室生物测定来预测。
