Woody semi-natural habitats serve as permanent habitats and hibernation sites for natural enemies and, through spillover processes, they play an important role in the biological control of insect pests. However, this service is also dependent on the amount and configuration of the dominating woody habitat types: linear landscape elements (hedgerows, shelterbelts), and more evenly extended plantations. Relating natural enemy action to the landscape context can help to identify the effect of woody habitats on biological control effectiveness. In the Central European agricultural landscapes such as in the Hungarian lowlands, where our study took place, woody linear elements are characterised by high, while woody areal elements, mostly plantations, by low biological and structural diversity. In this study, we aimed to determine which composition and configuration of woody linear and areal habitats in the landscape may enhance the effect of natural enemy action on plant damage caused by the cereal leaf beetle (CLB, Oulema melanopus). Herbivory suppression by natural enemies was assessed from the leaf damage difference between caged and open treatments. These exclusion experiments were carried out in 34 wheat fields on plants with controlled CLB infections. The results were related to landscape structure, quantified by different landscape metrics of both woody linear and areal habitats inside buffers between 150 and 500 m radii, surrounding the wheat fields. The exclusion of natural enemies increased the leaf surface loss caused by CLBs in all fields. Shelterbelts and hedgerows in 150–200 m vicinity of the wheat fields had a strong suppressing effect on CLB damage, while the presence of plantations at 250 m and further rather impeded natural enemy action. Our results indicate that shelterbelts and hedgerows may provide a strong spillover of natural enemies, thus contribute to an enhanced biological control of CLBs.

中文翻译：

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线性木质景观元素可能有助于减轻由谷叶甲虫引起的叶面损失

木质半自然栖息地是天敌的永久栖息地和冬眠地，通过外溢过程，它们在昆虫害虫的生物防治中发挥着重要作用。然而，这项服务还取决于主要木质栖息地类型的数量和配置：线性景观元素（绿篱、防护林）和更均匀扩展的种植园。将天敌行动与景观环境联系起来有助于确定木质栖息地对生物防治有效性的影响。在我们研究所在的匈牙利低地等中欧农业景观中，木质线性元素的特点是高度，而木质区域元素（主要是种植园）的生物和结构多样性较低。在这项研究中，我们旨在确定景观中木质线性和区域栖息地的哪些组成和配置可以增强天敌对谷叶甲虫（CLB，Oulema melanopus）造成的植物损害的影响。根据笼养和开放处理之间的叶片损伤差异评估天敌对食草动物的抑制。这些排除实验是在 34 个麦田中对受控制的 CLB 感染的植物进行的。结果与景观结构有关，由麦田周围 150 至 500 m 半径缓冲区内的木质线性和区域生境的不同景观指标量化。天敌的排除增加了所有领域中CLBs引起的叶面损失。麦田附近 150-200 m 的防护林和树篱对 CLB 损害有很强的抑制作用，而 250 m 处种植园的存在进一步阻碍了天敌的行动。我们的研究结果表明，防护林和树篱可能会提供强烈的天敌外溢，从而有助于增强对 CLB 的生物控制。