Department of Environmental Science, Policy and Management, University of California, 130 Mulford Hall Number 3114, Berkeley, California 94720, USA.
Ecol Appl. 2012 Oct;22(7):1936-48. doi: 10.1890/11-1844.1.
Farms benefit from pest control services provided by nature, but management of these services requires an understanding of how habitat complexity within and around the farm impacts the relationship between agricultural pests and their enemies. Using cage experiments, this study measures the effect of habitat complexity across scales on pest suppression of the cabbage aphid Brevicoryne brassicae in broccoli. Our results reveal that proportional reduction of pest density increases with complexity both at the landscape scale (measured by natural habitat cover in the 1 km around the farm) and at the local scale (plant diversity). While high local complexity can compensate for low complexity at landscape scales and vice versa, a delay in natural enemy arrival to locally complex sites in simple landscapes may compromise the enemies' ability to provide adequate control. Local complexity in simplified landscapes may only provide adequate top-down pest control in cooler microclimates with relatively low aphid colonization rates. Even so, strong natural enemy function can be overwhelmed by high rates of pest reproduction or colonization from nearby source habitat.
农场受益于自然界提供的害虫防治服务，但要管理这些服务，就需要了解农场内部和周围的生境复杂性如何影响农业害虫与其天敌之间的关系。本研究通过笼式实验，测量了不同尺度的生境复杂性对西兰花上小菜蛾 Brevicoryne brassicae 种群抑制的影响。研究结果表明，无论在景观尺度（通过农场周围 1 公里范围内的自然生境覆盖来衡量）还是在局部尺度（植物多样性）上，害虫密度的比例减少都随着复杂性的增加而增加。虽然高局部复杂性可以弥补景观尺度上的低复杂性，反之亦然，但在简单景观中，自然天敌到达局部复杂地点的延迟可能会降低它们提供充分控制的能力。在简化的景观中，局部复杂性可能仅在相对较低的蚜虫定殖率和较凉爽的小气候中提供充分的自上而下的害虫控制。即便如此，强大的天敌功能也可能被附近源生境中较高的害虫繁殖或定殖率所压倒。
