应用模糊聚类分析研究菜蚜种群动态

在分别描述了杭州郊区秋末冬初季节小白菜（Ｂｒａｓｓｉｃａｃａｍｐｅｓｔｒｉｓｓｓｐ．ｃｈｉｎｅｎｓｉｓ．）上菜蚜种群的数量动态和空间动态的基础上，应用模糊聚类分析法研究了菜蚜种群的数量和空间的整体动态。结果表明，桃蚜、萝卜蚜及其混合种群的数量动态均呈指数或Ｌｏｇｉｓｔｉｃ曲线变化，它们的空间格局呈聚集分布；而且聚集强度始终从高到低呈持续下降。运用模糊聚类法，可将其种群的整体动态分成４个时期，依次为：苗期（或移栽后的返青期）的迁入期，成株初期的增殖扩散期，成株后生长盛期的繁殖高峰期，外围叶片明显枯黄时的数量饱和期。作者据此对各个时期的菜蚜种群特征进行了具体分析。

A study of population dynamies of aphids on crucifer vegetable crops using the method of fuzzy clustering.

Systematic field sampling of aphids on the crucifer vegetable crops of Brassica campestris ssp.chinensis during late autumn to early winter was carried out in Hangzhou in 1990 and 1991.Using the sampling data,this paper first describes the numerical changes and spatial patterns of aphid populations,and then analyze the population dynamics by fuzzy clustering which takes into account both numerical changes and spatial patterns,The results indicate that the popu-lation abundance of Myzus persicae (Sulzer),Lipaphis erysimi Kaltenbach,and the combined popu-lation of the two aphids all followed an exponential or logistic curve,and all the populations were aggregated and the intensity of aggregation changed gradually from highly aggregated to loosely ag-gregated throughout the growth of the crop.According to the results of fuzzy clustering,the de-velopment of aphid population on a crop could be divided into the following four phases;immigra-tion phase,dispersion phase,maximum reproductive phase and the final plateau phase. The devel-opment of the four phases was closely associated with the growth stages of the crop.The charac-teristics of the aphid populations in each of the four phases were also described in some detail.