Stress magnitude matters: different intensities of pulsed water stress produce non-monotonic resistance responses of host plants to insect herbivores
Stress magnitude matters: different intensities of pulsed water stress produce non-monotonic resistance responses of host plants to insect herbivores
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DOI：
10.1111/j.1365-2311.2008.01053.x
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发表时间：
2009-02-01
影响因子：
2.2
通讯作者：
Dorn, Silvia
中科院分区：
文献类型：
--
作者：
Mody, Karsten;Eichenberger, Daniela;Dorn, Silvia
1.水分胁迫可能增加或降低植物对草食动物的适宜性。最近提出的“脉冲胁迫假说”建议考虑胁迫物候(脉冲胁迫与持续胁迫)来解释植物水分胁迫对食草动物行为的这些相互矛盾的影响。研究了不同胁迫强度对食叶昆虫(斜纹夜蛾)和韧皮部食性昆虫(苹果蚜虫)在苹果树上的表现和喜好的影响。这些植物没有受到胁迫，或者暴露在低强度或高强度的脉冲水分胁迫下。植物对不同胁迫水平的反应一般是单调的。生长、气孔导度(g(S))、叶片水分和老叶氮素浓度随胁迫强度的增加而降低，而幼叶氮素浓度和单位面积叶质量增加。叶片碳的稳定同位素组成(增量C-13)对干旱处理的响应不是单调的。C-13值在低胁迫植株中最高，在高胁迫植株中居中，在非胁迫植株中最低。毛虫的喜好和表现反应也是非单调的。非胁迫植株中等，低胁迫植株最少，高胁迫植株最吸引或适宜。在非胁迫条件下，棉铃虫种群增长最快，在低胁迫条件下最低。这些结果强调了水分胁迫强度对于草食动物和受干旱影响的植物之间相互作用的结果的重要性。他们表明，脉冲水分胁迫可能会增强或降低昆虫的食草动物性能和植物的抗性，这取决于胁迫强度。
1. Water stress may increase or reduce the suitability of plants for herbivores. The recently proposed 'pulsed stress hypothesis' suggests consideration of stress phenology (pulsed vs. continuous stress) to explain these conflicting effects of plant water stress on herbivore performance.2. This hypothesis was tested for the effect of differing stress intensity on performance and preference of insect herbivores belonging to different feeding guilds, namely leaf-chewing insects (Spodoptera littoralis caterpillars) and phloem-feeding insects (Aphis pomi aphids), on apple plants (Malus domestica). The plants were non-stressed or exposed to a low or high intensity of pulsed water stress.3. Plant responses to the different stress levels were generally monotonic. Growth, stomatal conductance (g(s)), leaf water, and old-leaf nitrogen concentration decreased, whereas young-leaf nitrogen concentration and leaf mass per area (LMA) increased with increasing stress intensity. The stable isotope composition of foliar carbon (delta C-13) responded non-monotonically to the drought treatments. The delta C-13 values were highest in low-stress plants, intermediate in high-stress plants, and lowest in non-stressed plants.4. The preference and performance responses of the caterpillars were also non-monotonic. Non-stressed plants were intermediately, low-stress plants least, and high-stress plants most attractive or suitable. Aphid population growth was highest on non-stressed plants and lowest on low-stress plants.5. The results highlight the importance of water stress intensity for the outcome of interactions between herbivores and drought-affected plants. They show that pulsed water stress may enhance or reduce insect herbivore performance and plant resistance, depending on stress intensity.