基于地统计学和GIS的化学农药胁迫下桃树桃蚜与草间钻头蛛种群空间格局

化学农药过量施用不仅杀死了害虫和自然天敌,也影响天敌与害虫之间的空间关系。桃园生态系统中草间钻头蛛(Hylyphantes graminicola)是桃蚜(Myzus persicae)的重要捕食性天敌,本文系统调查了化学农药长期胁迫下不同时期(4月中旬至9月上旬)桃树桃蚜和草间钻头蛛种群数量,并运用地统计学方法和地理信息系统(GIS)分析了桃树桃蚜和草间钻头蛛种群的空间结构,并采用基于高斯模型、指数模型、球型模型和圆型模型的普通克立格插值法模拟了其种群空间分布格局。结果表明,桃蚜和草间钻头蛛种群在10次调查期间均呈随机分布格局;桃蚜和草间钻头蛛空间分布距离相关性较弱,其变动范围均为6.863 0~43.174 1 m;桃蚜和草间钻头蛛的空间结构比例分别为0.788 8~0.983 9和0.811 6~0.980 6,块金值分别为0.254 2~4.896 3和0.218 4~0.749 9,偏基台值分别为0.010 5~0.250 0和0.004 8~0.075 7。本研究结果显示,长期使用化学农药致使桃树桃蚜和草间钻头蛛种群的空间结构比例值均大于0.7500,这表明化学农药胁迫下桃蚜和草间钻头蛛种群之间的跟随效应不明显,草间钻头蛛对桃蚜的捕食作用不强。

Geostatistics and GIS analysis of spatial patterns of Myzus persicae and Hylyphantes graminicola in peach orchards under chemical pesticide stress

The overuse of chemical pesticides not only kills insect pests and natural enemies, but also affects the spatial relationship between insect pests and their natural enemies. Hylyphantes graminicola is a key predator of Myzus persicae in peach orchard eosystems. In this paper, we systematically investigated M. persicae and its predator H. graminicola populations in peach orchards under chemical pesticide stress at different times (from mid April to early September), used geostatistics and geographic information system (GIS) to analyze the spatial structure, and used ordinary Kriging interpretation with Gaussian, Exponential, Spherical and Circular models to simulate the spatial distribution of the two species.The aim of the study was to understand the spacial distribution of M. persicae and its predator H. graminicola under long-term applicaiton of chemical pestcides and provide the theoretical support for ecological control of peach garden pests. The results suggested that both H. graminicola and M. persicae had random spatial arrangement within 10 iterative times of investigations. The proportions of spatical sturcture C0/(C+ C0)] of populations of H. graminicola and M. persicae were 0.788 80.983 9 and 0.811 60.980 6 indicating weak spacial relathship bewteen two populaitons under long-term chemical pestcide stress. The nugget values and partial sills of H. Graminicola, M. persicae were respectivel 0.254 2 4.896 3, 0.218 40.749 9 and 0.010 50.250 0, 0.004 80.075 7, respectively, indicating random spatial arrangement, too. The correlation of spatial distribution distance of two species was relatively weak, the distance ranges for the two species was 6.863 0 43.174 1 m. Though the model parameters of semivariograms for M. persicae and H. graminicola at different times were changed greatly due to population density, temperature, and peach growth, the spatial patterns of the two populations were random under long-term chemical pesticide stress. Our study demonstrated that under long-term and excessive use of chemical pesticides in peach orchards, the proportions of H. graminicola and M. persicae spatial structure was greater than 0.750 0, and their spatical patterns were random. This suggested that there was no obvious effect of H. graminicola on M. persicae and that H. graminicola had minimal predatory effect on M. persicae.