鸡冠刺桐叶片上刺桐姬小蜂虫瘿的分布规律

Distribution of Galls Induced by Quadrastichus erythrinae on Erythrina cristagalli Leaf

为研究刺桐姬小蜂在刺桐叶片上产卵危害及虫瘿分布特点，调查了鸡冠刺桐Erythrina cristagalli L．叶片上刺桐姬小蜂Quadrastichus erythrinae Kim虫瘿的数量和空间分布规律．结果表明，叶片上虫瘿主要分布于近叶柄处主脉两侧中下部区域，单个和2个虫瘿团的形式出现频次高于50％，以1—15个虫瘿团形式出现的虫瘿数量是相近的；鸡冠刺桐叶片上刺桐姬小蜂虫瘿呈聚集分布，且聚集程度较强，其分布形式符合负二项分布，分布的基本成分为个体群，且个体群大小随着虫瘿密度的变化呈幂方程形式增大，平均为10．9个；虫瘿聚集程度具有密度依赖性，即随着虫瘿密度增大，聚集强度也增大．虫瘿由均匀型格局向聚集型格局相互转化过程中聚集临界密度为每叶22．8个．

Quantitative and spatial distributions of Quadrastichus erythrinae Kim galls on Erythrina cristagalli L. mature leaves were investigated and analysed by the distribution parameters in the paper. The resuits indicated that： （ 1 ） the frequency of the galls at the parts beside the main vein near the petiole was more than 50% on erythrina leaf; （2） the probability of the gall appearing in one and two-galls group in galls was over 50% and the gall quantities in 1 -15-galls groups were similar; （3） the spatial distribution of the galls on leaves was aggregating based on the spatial pattern parameters, and its basic element for distribution was clusters of individuals in which the clusters of individuals increased with the gall density; （4） the aggregation degree was dependent on gall density, and the density threshod between the spatial distribution of uniform and aggregation was 22. 8 galls/leaf.