Plant defense synergies and antagonisms affect performance of specialist herbivores of common milkweed
Plant defense synergies and antagonisms affect performance of specialist herbivores of common milkweed
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DOI：
10.1002/ecy.3915
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发表时间：
2022-12-26
期刊：
影响因子：
4.8
通讯作者：
Agrawal, Anurag A.
中科院分区：
文献类型：
--
作者：
Edwards, Collin B.;Ellner, Stephen P.;Agrawal, Anurag A.
作为一般规则，植物防御具有多种特征的食草动物。防御协同假说认为，与其独立功效相比，某些特征与其他特征共同表达时更有效。然而，这种假设很少在植物化学混合物之外进行测试，也很少在田间条件下进行测试。我们测试了多个防御性状的共同马利筋（马利筋）之间的协同作用，通过测定两个专家咀嚼食草动物在自然种群中的植物的性能。我们采用回归和随机森林的新应用，以确定防御性状之间的协同作用和拮抗作用。我们发现了第一个直接的经验证据，两个以前假设的防御协同作用马利筋（乳胶的次生代谢产物，乳胶的毛状体），并确定了许多其他潜在的协同作用和拮抗作用。我们最有力的证据防御协同作用之间的叶质量单位面积和低氮含量，鉴于这些“叶经济”性状通常在马利筋共变，防御协同作用可以加强他们的共同表达。我们报告说，每一个植物防御性状表现出依赖于环境的影响，对食草动物，和增加性状的表达可能是有益的食草动物的某些范围内观察到的表达。本文提出的新方法和发现补充了植物防御多样性研究的更多机械方法，并提供了迄今为止最好的证据，证明多种植物防御在对昆虫的影响中协同作用。植物防御协同作用对高度专业化的食草动物，如图所示，是一致的，这些拮抗剂之间正在进行的相互进化。
As a general rule, plants defend against herbivores with multiple traits. The defense synergy hypothesis posits that some traits are more effective when co-expressed with others compared to their independent efficacy. However, this hypothesis has rarely been tested outside of phytochemical mixtures, and seldom under field conditions. We tested for synergies between multiple defense traits of common milkweed (Asclepias syriaca) by assaying the performance of two specialist chewing herbivores on plants in natural populations. We employed regression and a novel application of random forests to identify synergies and antagonisms between defense traits. We found the first direct empirical evidence for two previously hypothesized defense synergies in milkweed (latex by secondary metabolites, latex by trichomes) and identified numerous other potential synergies and antagonisms. Our strongest evidence for a defense synergy was between leaf mass per area and low nitrogen content; given that these "leaf economic " traits typically covary in milkweed, a defense synergy could reinforce their co-expression. We report that each of the plant defense traits showed context-dependent effects on herbivores, and increased trait expression could well be beneficial to herbivores for some ranges of observed expression. The novel methods and findings presented here complement more mechanistic approaches to the study of plant defense diversity and provide some of the best evidence to date that multiple classes of plant defense synergize in their impact on insects. Plant defense synergies against highly specialized herbivores, as shown here, are consistent with ongoing reciprocal evolution between these antagonists.