At small spatial scales, attraction or deterrence of herbivores by plant neighbors can alter the susceptibility of plants to damage (i.e., associational effects). Given the patchy nature of plants and insect herbivory, we hypothesized that induced resistance may play an important role in mitigating such spatial variability. To test this notion, we first documented neighbor effects between two closely related and co‐occurring plant species in natural populations, and second, we measured how these effects changed after inducing plant resistance in a common garden. In wet fields and marshes of Northeastern North America, boneset (Eupatorium perfoliatum) is the primary host for the herbivorous beetle Ophraella notata. Across two years of surveys at multiple sites, we found that Joe Pye weed (Eutrochium maculatum) was a secondary host to O. notata and was more likely to receive beetle eggs when it grew near boneset, constituting a negative neighbor effect (associational susceptibility) for Joe Pye weed. Reciprocally, there were trends of reduced susceptibility for boneset when it grew near Joe Pye weed (a positive neighbor effect), but this pattern was less consistent over space and time. In the common garden, we manipulated patches, each with a center (focal) and surrounding (neighbor) plants, with focal plants of each species either induced by the plant hormone jasmonic acid or left as controls. While neighbor effects prior to induction mirrored the pattern in surveys, induction was most effective in reducing beetle oviposition on focal plants in heterospecific groups. This effectively eliminated negative neighbor effects (susceptibility) for Joe Pye weed, the less preferred plant species. However, in conspecific patches, induction had minimal effect on either species' susceptibility to beetles. Given the importance of spatial variation generally and the ubiquity of neighbor effects in plant communities, we suggest that inducible resistance may be an important mechanism to cope with spatial heterogeneity in susceptibility to herbivores.

中文翻译：

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诱导的抗性减轻了植物邻居对草食动物敏感性的影响

在较小的空间尺度上，植物邻居对草食动物的吸引或威慑会改变植物对损害的敏感性（即缔合效应）。考虑到植物和昆虫食草的斑驳性质，我们假设诱导的抗性可能在减轻这种空间变异性中起重要作用。为了验证这一观点，我们首先记录了自然种群中两个密切相关且同时存在的植物物种之间的邻居效应，其次，我们测量了在共同花园中诱导植物抗性后这些效应的变化。在北美东北部的湿地和沼泽中，骨结（（Eupatorium perfoliatum）是食草甲虫Ophraella notata的主要寄主。在多个地点进行的两年调查中，我们发现Joe Pye杂草（Eultrochium maculatum）是Not.notata的次要寄主。并且当它长到骨骼附近时更可能会收到甲虫卵，这对乔·皮（Joe Pye）杂草构成了负面的邻居效应（关联敏感性）。与此相反，当骨生长在乔·派伊杂草附近时，有降低对骨的敏感性的趋势（积极的邻居效应），但是这种模式在空间和时间上并不一致。在公共花园中，我们操纵了斑块，每个斑块都有中心植物（焦点植物）和周围的植物（邻居），每种植物的焦点植物都是由植物激素茉莉酸诱导的或作为对照。虽然诱导前的邻居效应反映了调查中的模式，但诱导最有效地减少了异特异群体中焦点植物上的甲虫产卵。这有效地消除了Joe Pye杂草的负面邻居影响（敏感性），次要的植物种类。但是，在同种斑块中，诱导对两种物种对甲虫的敏感性影响最小。考虑到一般而言空间变异的重要性以及植物群落中普遍存在的邻近效应，我们建议诱导抗性可能是应对食草动物敏感性空间异质性的重要机制。