农田景观格局对华北地区麦田早期瓢虫种群发生的影响

【目的】评价在华北地区农田景观格局对早期麦田瓢虫种群数量的影响。【方法】本文通过黄板诱集法调查4月中下旬麦田瓢虫成虫数量,对不同空间尺度下的景观格局进行调查与主成分分析,并结合"校正后赤池信息准则(AICc)"对构建的线性模型进行筛选,评估了景观因子对瓢虫种群数量的影响。【结果】在半径0.5、1.0、1.5、2.0 km 4个景观尺度下以林地为主的非作物生境均有利于麦田瓢虫成虫种群数量的增加,在较大的尺度范围内村落和休耕地与麦田瓢虫的发生数量正相关。其中,0.5 km尺度下的景观因子最能预测麦田瓢虫种群数量,其中林地面积和瓢虫种群数量呈正相关,而麦田瓢虫却随着景观多样性指数的增加而降低。此外,龟纹瓢虫作为麦田早期瓢虫的优势种类对景观多样性的响应与瓢虫复合种群一致。【结论】在华北地区,农田景观系统中非作物生境有利于麦田早期瓢虫种群的发生。

Effects of landscape pattern on the occurrence of ladybeetles in wheat fields in northern China

Objectives] To determine the effects of landscape pattern on ladybeetle abundance in wheat fields during the early growing season in northern China. Methods] We investigated the abundance of adult ladybeetles in wheat fields using yellow sticky cards. We analyzed the effects of landscape pattern on the occurrence of ladybeetles by identifying the land use pattern by ground verification, then using adjusted Akaike’s information Criterion (AICc) to compare general linear models containing principal landscape variables and landscape diversity at four different scales (0.5, 1.0, 1.5, 2.0 km). Results] The presence of forest benefited ladybeetle abundance at all landscape scales, and villages and fallow fields also enhanced ladybeetle abundance at larger landscape scales. Overall, landscape features at 0.5 km best predicted ladybeetle abundance, which was positively correlated with the proportion of forest, and negatively correlated with the landscape diversity index. The abundance of Propylaea japonica, the dominant ladybeetle species in wheat fields, had the same relationship with landscape parameters as the ladybeetle community as a whole. Conclusion] Non-crop habitats in the northern China agricultural ecosystem facilitate the occurrence of ladybeetles in wheat fields during the early growing season.