LINV - Department of Agri-Food Production and Environmental Science, University of Florence, Viale delle Idee, 30, I-50019, Sesto Fiorentino, Florence, Italy.
Department of Entomology and Nematology, University of California, Davis, California, 95616, USA.
Ecology. 2017 Jun;98(6):1693-1699. doi: 10.1002/ecy.1846. Epub 2017 May 11.
Anti-herbivore defense shows high levels of both inter- and intraspecific variability. Defending against herbivores may be costly to the plant when it requires a tradeoff in allocation between defense and other missed opportunities, such as reproduction. Indeed, the plastic expression of defensive traits allows the plant to invest resources in defense only when the risk of being damaged actually increases, avoiding wasted resources. Plants may assess risk by responding to volatile cues emitted by neighbors that are under attack. Most plastic responses likely depend on environmental conditions. In this experiment, we investigated the effect of water availability on resistance induced by volatile cues in sagebrush. We found that plants receiving additional water over summer and/or volatile cues from neighbor donor plants showed reduced herbivore damage compared to control plants. Interestingly, we found no evidence of interactions between additional water and volatile cues. We performed an inferential analysis comparing historical records of the levels of herbivore damage during different years that had different temperature and precipitation accumulations. Results confirmed findings from the experiment, as the regression model indicated that sagebrush was better defended during wetter and hotter seasons. Reports from the literature indicated that sagebrush is extremely sensitive to water availability in the soil. We suggest that water availability may directly affect resistance of herbivory as well as sensitivity to cues of damage. Costs and benefits of allocating resources to defensive traits may vary with environmental conditions.
抗食草动物防御表现出高度的种间和种内变异性。当植物在防御和其他错过的机会（如繁殖）之间的分配上需要权衡时，防御食草动物可能会对植物造成代价。事实上，防御性状的可塑性表达使植物只有在受到损害的风险实际增加时才会投资于防御，从而避免浪费资源。植物可以通过对受到攻击的邻居发出的挥发性线索做出反应来评估风险。大多数塑性反应可能取决于环境条件。在这个实验中，我们研究了水分可用性对迷迭香中挥发性线索诱导的抗性的影响。我们发现，与对照植物相比，夏季接受额外水分和/或来自邻居供体植物挥发性线索的植物受到的食草动物损害较小。有趣的是，我们没有发现额外水分和挥发性线索之间存在相互作用的证据。我们进行了一项推理分析，比较了不同年份不同温度和降水积累的食草动物损害水平的历史记录。结果证实了实验结果，因为回归模型表明迷迭香在更湿润和更炎热的季节得到了更好的保护。文献中的报告表明，迷迭香对土壤中的水分可用性极为敏感。我们建议，水分可用性可能直接影响抗食草动物的能力以及对损害线索的敏感性。分配资源用于防御性状的成本和收益可能随环境条件而变化。
