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Abstract：
Semi-natural field borders are frequently used in midwestern U.S. sustainable agriculture. These habitats are meant to help diversify otherwise monocultural landscapes and provision them with ecosystem services, including biological control. Predatory and parasitic arthropods (i.e., potential natural enemies) often flourish in these habitats and may move into crops to help control pests. However, detailed information on the capacity of semi-natural field borders for providing overwintering refuge for these arthropods is poorly understood. In this study, we used soil emergence tents to characterize potential natural enemy communities (i.e., predacious beetles, wasps, spiders, and other arthropods) overwintering in cultivated organic crop fields and adjacent field borders. We found a greater abundance, species richness, and unique community composition of predatory and parasitic arthropods in field borders compared to arable crop fields, which were generally poorly suited as overwintering habitat. Furthermore, potential natural enemies tended to be positively associated with forb cover and negatively associated with grass cover, suggesting that grassy field borders with less forb cover are less well-suited as winter refugia. These results demonstrate that semi-natural habitats like field borders may act as a source for many natural enemies on a year-to-year basis and are important for conserving arthropod diversity in agricultural landscapes.
摘要：
美国中西部可持续农业经常使用半自然田间边界。这些栖息地旨在帮助多样化其他单一文化景观，并为它们提供生态系统服务，包括生物控制。捕食性和寄生性节肢动物(即，潜在的天敌）通常在这些栖息地中蓬勃发展，并可能进入农作物以帮助控制害虫。然而,关于半自然田间边界为这些节肢动物提供越冬避难所的能力的详细信息知之甚少。在这项研究中,我们使用土壤出苗帐篷来表征潜在的天敌群落(即，捕食的甲虫,黄蜂,蜘蛛,和其他节肢动物）在栽培的有机作物田地和相邻的田地边界越冬。我们发现了更丰富的资源，物种丰富度,和独特的群落组成的掠夺性和寄生节肢动物在田间边界与耕地相比，通常不适合作为越冬栖息地。此外，潜在的天敌倾向于与forb覆盖呈正相关，与草覆盖呈负相关，这表明草丛覆盖较少的草地边界不太适合作为冬季避难所。这些结果表明，像田野边界这样的半自然栖息地可能每年都是许多天敌的来源，对于保护农业景观中的节肢动物多样性至关重要。
