棉田烟粉虱种群的空间格局

在转Bt基因棉花（国抗22号）和对应的常规亲本棉（泗棉3号）棉田中对烟粉虱的垂直分布和水平分布格局进行了调查.结果表明，7月份烟粉虱成虫在棉株垂直方向上分层不明显；8月份以后，棉株上层虫口密度显著高于中层和下层.在水平分布上，烟粉虱成虫和若虫的空间格局基本相同，种群密度较低时呈均匀分布，较高时呈聚集分布，且种群密度越高，聚集强度越大.从整个发生期间看，烟粉虱成虫和若虫都处于扩散和聚集交替进行的动态过程中.国抗22号和泗棉3号棉田烟粉虱的空间格局基本一致.

Spatial patterns of Bemisia tabaci (Gennadius) population in cotton fields

Field investigations on the vertical and horizontal distribution patterns of Bemisia tabaci (Gennadius) population on Bt cotton Guokang No.22 and non-Bt cotton Simian No. 3 showed that in July,no obvious difference was found in the vertical distribution of B.tabaci population on cotton plant,but in August,the population density was significantly higher on the upper part of cotton plant than on its middle and lower parts.The horizontal distribution patterns of B.tabaci adult and nymph were similar.B.tabaci distributed evenly on cotton leaves when its population density was low,but aggregated when its population density was high.The greater the population density,the higher the aggregation rate was observed.Throughout the incidence stage,B.tabaci adult and nymph aggregated and diffused alternatively.No significant difference was observed in the spatial distribution pattern of B.tabaci on Bt and non-Bt cotton plants.