Abstract Declines in functional biodiversity, caused by changing structure and composition of agricultural landscapes, endanger the provision and stability of important ecosystem services, such as biological pest control. Understanding how spatiotemporal landscape changes affect the dynamics of pests, natural enemies and their activity can help safeguard and improve pest control in crops. Here, we tested the influence of spatial and temporal differences in landscape composition of crops (landscape-wide crop rotation diversity and % pest host crops) on the density and seasonal variability of cabbage pests, parasitoids and rates of aphid parasitism and predation. We also tested whether low seasonal variability of pests and parasitoids translates into stable and high pest control, reduced crop damage and higher yields. We show that landscapes with diverse crop rotations increased aphid parasitism, but also leaf-chewing pest density and seasonal stability. Leaf-chewing pest density decreased with increasing % host crops from year to year, suggesting a dilution effect. However, parasitoid density increased in these landscapes. We found no relationship between predation or parasitism and crop damage or yield. Further, stable parasitoid populations led to more stable parasitism rates. These findings highlight that impacts of spatially and temporally changing landscapes are pest- and enemy-specific, and tradeoffs for landscape management may occur. Appropriately managing the diversity and composition of arable crops in farmed landscapes may help influence species occurrences, without converting fertile land to non-crop habitat.

中文翻译：

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景观作物组成的时空变化对白菜害虫、寄生蜂和生物害虫防治的密度和​​季节性变化的影响不同

摘要 农业景观结构和组成的变化导致功能生物多样性下降，危及重要生态系统服务的提供和稳定性，如生物害虫防治。了解时空景观变化如何影响害虫、天敌及其活动的动态可以帮助保护和改善作物害虫防治。在这里，我们测试了作物景观组成的空间和时间差异（景观范围的作物轮作多样性和害虫寄主作物百分比）对卷心菜害虫、寄生蜂和蚜虫寄生和捕食率的密度和季节性变化的影响。我们还测试了害虫和寄生蜂的低季节性变化是否会转化为稳定和高度的害虫控制、减少作物损害和提高产量。我们表明，具有不同作物轮作的景观增加了蚜虫的寄生，但也增加了啃食害虫的密度和季节性稳定性。咀嚼叶害虫密度随着寄主作物百分比的逐年增加而降低，表明存在稀释效应。然而，这些景观中的寄生蜂密度增加了。我们发现捕食或寄生与作物损害或产量之间没有关系。此外，稳定的寄生蜂种群导致更稳定的寄生率。这些发现强调了空间和时间变化的景观的影响是特定于害虫和敌人的，并且可能会发生景观管理的权衡。适当管理耕地景观中可耕作物的多样性和组成可能有助于影响物种的发生，而不会将肥沃的土地转变为非作物栖息地。