Mauffette Yves, Oechel Walter C
Biology Department, San Diego State University, 92182, San Diego, CA, USA.
Oecologia. 1989 Jun;79(4):439-445. doi: 10.1007/BF00378658.
The perennial foliage of the California coast live oak (Quercus agrifolia Nee) permits herbivores to feed on this oak species throughout the year. Patterns of herbivory for a two-year period on Q. agrifolia were observed in relation to seasonal and age-related changes in the nutritional and defensive characteristics of leaves. Nitrogen and phosphorus contents were higher in new leaves compared to mature foliage. Structural compounds (e.g., cellulose) in leaves rapidly increased with age. Concentrations of tatal phenolics (Folin-Denis) and astringency were higher in new foliage, and concentrations of condensed tannins gradually increased as the leaves matured. Peaks of herbivore damage were observed in June and in September-October, and were caused by outbreaks of the California oak moth (Phryganidia californica). P. californica, a bivoltine oak specialist, exhibited feeding preferences in June for old leaves over emerging leaves, and showed no preferences for leaf classes in September. These results suggest that P. californica is adapted to survive on nutritionally poor foliage and to circumvent "quantitative defenses" such as condensed tannins.
加利福尼亚海岸活栎（Quercus agrifolia Nee）的多年生树叶使得食草动物能够全年以这种栎树为食。针对二年生的加州海岸活栎，观察了其取食模式与叶片营养及防御特征的季节性和年龄相关变化之间的关系。与成熟叶片相比，新叶中的氮和磷含量更高。叶片中的结构化合物（如纤维素）随年龄迅速增加。新叶中总酚（福林-丹尼斯法）浓度和涩味更高，随着叶片成熟，缩合单宁浓度逐渐增加。食草动物造成的损害高峰出现在6月以及9月至10月，是由加州栎蛾（Phryganidia californica）的爆发引起的。加州栎蛾是一种双化性栎树专食性昆虫，6月时偏好取食老叶而非新叶，9月时对不同叶类没有偏好。这些结果表明，加州栎蛾能够适应在营养贫瘠的叶片上生存，并规避缩合单宁等“定量防御”。
