Specific impacts of two root herbivores and soil nutrients on plant performance and insect-insect interactions
Specific impacts of two root herbivores and soil nutrients on plant performance and insect-insect interactions
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DOI：
10.1111/j.1600-0706.2013.00434.x
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发表时间：
2013-12-01
期刊：
影响因子：
3.4
通讯作者：
Agrawal, Anurag A.
中科院分区：
文献类型：
--
作者：
Erwin, Alexis C.;Geber, Monica A.;Agrawal, Anurag A.
土栖昆虫通常共同出现，并同时以地下植物部分为食，但对植物和昆虫性能的损害和后果的模式仍然很难确定。我们测试了两种食根昆虫如何影响多年生植物的性能以及同种和异种昆虫的质量和存活。由于根系损伤预计会损害根系吸收养分的能力，我们还评估了土壤肥力如何改变地下植物-昆虫和昆虫-昆虫相互作用。具体而言，我们增长了常见的马利筋在低或高营养土壤中，并增加了七个密度的马利筋甲虫Tetraopes tetraophthalmus，线虫（主要是Hypnoides peculatus），或这两个物种。根损害的位置和严重程度是物种特异性的：Tetraopes造成59%以上的损害主根比线虫，线虫造成近7倍以上的损害细根比Tetraopes。Tetraopes损害地上部，主根和细根生物量下降，但大量的损害线虫没有减少任何组成部分的植物生物量。随着土壤养分的增加，主根生物量增加了3倍以上，细根生物量增加了5倍以上，当线虫比Tetraopes存在。我们检测到昆虫身份和养分供应对昆虫质量的交互作用。在高营养下，线虫质量总体下降了19%，并且不受Tetraopes存在的影响。相比之下，Tetraopes质量整体增加了114%，并且当线虫也存在时显著更高。线虫的存活率下降的Tetraopes的存在下，和两个物种的生存与同种密度呈负相关。我们的结论是，昆虫的身份，密度和土壤养分是重要的调解模式和后果的根损害，并建议这些因素可能占一些矛盾的植物反应地下草食动物的文献报道。
Soil-dwelling insects commonly co-occur and feed simultaneously on belowground plant parts, yet patterns of damage and consequences for plant and insect performance remain poorly characterized. We tested how two species of root-feeding insects affect the performance of a perennial plant and the mass and survival of both conspecific and heterospecific insects. Because root damage is expected to impair roots' ability to take up nutrients, we also evaluated how soil fertility alters belowground plant-insect and insect-insect interactions. Specifically, we grew common milkweed Asclepias syriaca in low or high nutrient soil and added seven densities of milkweed beetles Tetraopes tetraophthalmus, wireworms (mainly Hypnoides abbreviatus), or both species. The location and severity of root damage was species-specific: Tetraopes caused 59% more damage to main roots than wireworms, and wireworms caused almost seven times more damage to fine roots than Tetraopes. Tetraopes damage decreased shoot, main root and fine root biomass, however substantial damage by wireworms did not decrease any component of plant biomass. With the addition of soil nutrients, main root biomass increased three times more, and fine root biomass increased five times more when wireworms were present than when Tetraopes were present. We detected an interactive effect of insect identity and nutrient availability on insect mass. Under high nutrients, wireworm mass decreased 19% overall and was unaffected by the presence of Tetraopes. In contrast, Tetraopes mass increased 114% overall and was significantly higher when wireworms were also present. Survival of wireworms decreased in the presence of Tetraopes, and both species' survival was negatively correlated with conspecific density. We conclude that insect identity, density and soil nutrients are important in mediating the patterns and consequences of root damage, and suggest that these factors may account for some of the contradictory plant responses to belowground herbivory reported in the literature.