We assess the effects of changing land use and crop management on alfalfa insect abundance by comparing it in 50 alfalfa fields when they were inserted in landscapes with different proportions of arable crops and orchards. Land use in a buffer of 500 m was assessed, and alfalfa insect abundance was estimated with sticky yellow traps. The number of catches of several herbivores and predators was related to the proportion of landscape components and several field variables. Results indicated that the proportion of orchards in the buffer negatively affected the abundance of predators on alfalfa, likely because orchards treated with pesticides are a sink for predators moving in the landscape, among other possible causes. Other landscape variables such as noncrop habitats, winter cereals, and landscape diversity analysed by the Shannon index had a minor influence. Among field variables, field size influenced positively the abundance of insects on alfalfa, whereas alfalfa growth stage and age affected positively or negatively the different herbivores and predators. Of course, abundance of predators and prey was affected by the abundance of prey and predators, respectively. These findings suggest that a high proportion of intensively managed crops (orchards) in the landscape interferes with the role of alfalfa as a reservoir of predatory insects for adjacent crops and that the responses to local and landscape structures are temporal and species-specific as previously concluded for maize. Consequently, landscape and field management strategies to improve pest control must consider both types of variables as well as their changing influence when we modify them.

我们通过将 50 个苜蓿田插入具有不同比例的耕地作物和果园的景观中进行比较，来评估改变土地利用和作物管理对苜蓿昆虫丰度的影响。评估了 500 m 缓冲区中的土地利用，并使用粘性黄色陷阱估计了苜蓿昆虫的丰度。几种食草动物和捕食者的捕捞数量与景观成分的比例和几个田间变量有关。结果表明，缓冲区中果园的比例对苜蓿捕食者的数量产生了负面影响，这可能是因为用杀虫剂处理过的果园是在景观中移动的捕食者的一个汇，以及其他可能的原因。其他景观变量，如非作物栖息地、冬季谷物、香农指数分析的景观多样性影响较小。在田间变量中，田地大小对苜蓿上昆虫的丰度有积极影响，而苜蓿的生长阶段和年龄对不同的食草动物和捕食者有积极或消极的影响。当然，捕食者和猎物的丰度分别受到猎物和捕食者丰度的影响。这些发现表明，景观中高比例的集约化管理作物（果园）干扰了苜蓿作为邻近作物捕食性昆虫储存库的作用，并且对当地和景观结构的反应是时间和物种特异性的，如前所述对于玉米。最后，