玉米田截形叶螨种群动态的研究

1999～2001年于内蒙古巴彦卓尔盟杭锦后旗研究了玉米田截形叶螨田间种群动态。结果表明．截形叶螨在玉米田的空间格局为聚集格局，随着叶螨种群密度的上升，其聚集强度下降应用最优分割法将玉米截形叶螨田间种群动态划分为5个阶段：①7月上旬前为种群初建期，叶螨在玉米田刚开始发生，种群数量很低，只分布在极少数植株上；②7月中旬为种群缓慢增长期，种群数量低，增长缓慢，聚集强度高；③从7月下旬至8月中旬为种群快速增长期，种群数量高，增长迅速，叶螨分布至全田，聚集强度下降；④8月下旬为种群高峰期，种群数量最高，聚集强度较低；⑤9月以后为玉米截形叶螨种群的衰落期，由于玉米受害严重及玉米进入生长后期，中下部叶片大部分均已枯死，上部叶片也已老化营养水平下降，加之气温下降，叶螨种群数量迅速下降。

Population dynamics of Tetranychus truncatus in corn fields

The population dynamics of Tetranychus truncatus in corn fields were investigated in Hangjinghouqi,Bayanzhuoer League,Inner Mongolia from 1999 to 2001.The results showed that the spatial patterns of the mites were aggregated,and the aggregation intensity decreased with increasing population density.With optimal sorting method,the natural population dynamics of T.truncatus were divided into five stages,(i.e,)(1)the population began to colonize with low quantity on a few plants in June and early July,(2)increased slowly with low density and high aggregation intensity in mid-July,(3)rose quickly and distributed in whole corn fields with high density and declining aggregation intensity from the end of July to mid-August,(4)reached the highest with the lowest aggregation intensity in the end of August,and(5) declined quickly in September.