Plant water‐use strategies as mediators of herbivore drought response: Ecophysiology, host plant quality and functional traits
Plant water‐use strategies as mediators of herbivore drought response: Ecophysiology, host plant quality and functional traits
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DOI：
10.1111/1365-2745.14059
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发表时间：
2022-12
影响因子：
5.5
通讯作者：
A. N. Carvajal Acosta;A. Agrawal;Kailen A. Mooney
中科院分区：
文献类型：
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作者：
A. N. Carvajal Acosta;A. Agrawal;Kailen A. Mooney
草食性昆虫对植物干旱胁迫的反应可以从积极到消极，了解这种变化的原因一直具有挑战性。我们测试了与干旱梯度相关的植物性状值是否可能是这种变化的基础，以及这种影响在两个昆虫摄食行会之间如何变化。在此，我们提出与干旱环境适应性相关的植物性状值将导致实验干旱对食草动物产生积极影响，这些植物物种将适应性资源从抗性转移到维持胁迫下的性能。相比之下，具有与适应中等环境相关的性状值的植物将导致干旱的负面影响，因为这些物种会失去活力，从而降低其寄主质量。我们对13种适应多种环境条件的乳草（Asclepias属）以及一种专业噬叶动物（黑脉金斑蝶）和树液取食动物（夹竹桃蚜虫）的食草性表现进行了实验操作，以验证这些预测。我们将植物暴露在生理校准的物种特异性浇水制度中，以最大化（100%）或减少（50%）气孔导度，然后监测草食动物的表现。干旱胁迫对乳草类食草动物存活率的影响从强正效应（增加50%）到强负效应（减少80%）不等，但这种影响在两种食草动物之间并不一致。与干旱适应相关的植物性状值与黑脉金斑蝶的存活率以预测的方式相关，例如高水分利用效率（WUE）和低相对含水量（RWC）的马利筋物种增加了黑脉金斑蝶在干旱下的存活率。相反，蚜虫的存活与干旱适应性状值无关。干旱引起的植物质量变化与两种食草动物的存活率均呈负相关。具体地说，在干旱条件下，马利筋种类增加了果仁内酯浓度，降低了帝王蝶和蚜虫的存活率。合成。我们证明了干旱对食草动物的间接影响在密切相关的植物物种和共生的昆虫食草动物之间存在巨大差异。反过来，我们提供的证据表明，这种变化可以通过植物性状来解释，这些性状与咀嚼叶子的植物适应干旱和中度环境有关，而不是取食汁液的植物，这种影响是由干旱引起的化学防御变化介导的。
The response of herbivorous insects to plant drought stress can range from positive to negative, and it has been challenging to understand the causes of this variation. We tested whether plant trait values associated with aridity gradients might underlie this variation and how such effects vary between two insect feeding guilds. Here, we propose that plants trait values associated with adaptation to arid environments would result in positive effects of experimental drought on herbivores, with such plant species adaptively shifting resources away from resistance to maintain performance under stress. In contrast, plants with trait values associated with adaptation to mesic environments would result in negative effects of drought because such species lose vigour and thus decrease their host quality. We tested these predictions using experimental manipulations in 13 milkweed species (genus Asclepias) adapted to a wide range of environmental conditions and the herbivore performance of a specialist leaf‐chewer (monarch butterfly; Danaus plexippus) and sap‐feeder (oleander aphid; Aphis nerii). We exposed plants to physiologically calibrated species‐specific watering regimes to maximize (100%) or reduce (50%) stomatal conductance and then monitored herbivore performance. The effects of drought stress on herbivore survival ranged from strongly positive (50% increase) to strongly negative (80% decrease) among milkweed species, but these effects were inconsistent between the two herbivores. Plant trait values associated with adaptation to aridity were correlated with monarch survival in the predicted manner, such that milkweed species with high water‐use efficiency (WUE) and low relative water content (RWC) increased monarch survival under drought. In contrast, aphid survival was unrelated to arid‐adapted trait values. Drought‐induced changes in plant quality were negatively associated with both herbivore survivals. Specifically, milkweed species that increased cardenolides concentration under drought conditions decreased monarch and aphid survival. Synthesis. We demonstrated that the indirect effects of drought on herbivores varied tremendously among closely related plant species and between co‐occurring insect herbivores. We in turn present evidence that some of this variation is explained by plant traits associated with adaptation to arid versus mesic environments for leaf‐chewers but not sap‐feeders and that such effects are mediated by drought‐induced changes in chemical defences.