关键词: 桃蚜, 种群空间动态, 负二项分布K值, 时序动态

Abstract: Systematic sampling of Myzus persicae on crucifer vegetables (Brassica spp.)was carried out during 1990-1992 to study its spatial pattern on the crops. From the sampling data, values of each of four different dispersion (or aggregation) indices were calculated, and their correlations with mean densities were evaluated. The valueof K of negative binomial distribution was shown to be poorly correlated with densities, and thus it was chosen to describe the spatial pattern and its time series dynamics in the aphid population. The results revealed that the population was aggregated throughout the year on all crops examined. However, the intensity of aggregationchanged seasonally. Each year, there were two obvious peaks of dispersal, around May and November respectively; likewise, there were two aggregated peaks, the first one during June to July when aphids emigrated from the fields, and the second one during September to October when aphids immigrated into the fields. The change pattern of aggregation intensity throughout the growth of a crop differed between seasons. From spring to summer, the population changed from highly aggregated to loosely aggregated and then to highly ggregated again. From autumn to winter, the population changed gradually from highly aggregated to loosely aggregated, and from winter to spring, the intensity of aggregation seemed to fluctuate randomly. Factors which could be correlated to the spatial pattern and its dynamics in the aphid popula tion, especially the possible influence of temperature and plant nutrition, are discussed.

Key words: Myzus persicae, population spatial dynamics, K of negative binomial, time series dynamics