CIAT (Centro Internacional de Agricultura Tropical), Apartado Aereo 6713, Call, Colombia.
Ecol Appl. 2011 Mar;21(2):539-46. doi: 10.1890/10-0393.1.
Modern restructuring of agricultural landscapes, due to the expansion of monocultures and the resulting elimination of non-crop habitat, is routinely blamed for rising populations of agricultural insect pests. However, landscape studies demonstrating a positive correlation between pest densities and the spatial extent of crop monocultures are rare. We test this hypothesis with a data set from 140 subsistence farms in the Andes and find the inverse correlation. Infestations by the Andean potato weevil (Premnotrypes spp.), the most important pest in Andean potato agriculture, decrease with increasing amounts of potato in the landscape. A statistical model predicts that aggregating potato fields may outperform the management of Andean potato weevils by IPM and chemical control. We speculate that the strong pest suppression generated by aggregating potato fields may partly explain why indigenous potato farmers cluster their potato fields under a traditional rotation system common in Andean agriculture (i.e., "sectoral fallow"). Our results suggest that some agricultural pests may also respond negatively to the expansion of monocultures, and that manipulating the spatial arrangement of host crops may offer an important tool for some IPM programs.
由于单一栽培的扩张以及由此导致的非作物生境的消除，现代农业景观结构的重组通常被归咎于农业虫害的增加。然而，很少有景观研究表明害虫密度与作物单一栽培的空间范围之间存在正相关关系。我们利用来自安第斯山脉 140 个自给农业农场的数据集对此假设进行了检验，结果发现了负相关关系。安第斯马铃薯象鼻虫（Premnotrypes spp.）的侵害——安第斯马铃薯农业中最重要的害虫——随着景观中马铃薯数量的增加而减少。一个统计模型预测，将马铃薯田集中起来可能比通过 IPM 和化学控制来管理安第斯马铃薯象鼻虫的效果更好。我们推测，集中种植马铃薯田所产生的强烈害虫抑制作用可能部分解释了为什么土著马铃薯种植者在安第斯农业中常见的传统轮作系统（即“扇形休耕”）下将他们的马铃薯田集中在一起。我们的结果表明，一些农业害虫也可能对单一栽培的扩张做出负面反应，而操纵宿主作物的空间排列可能为某些 IPM 计划提供一个重要工具。
