桃-点叶蝉及其天敌草间小黑蛛种群三维空间格局动态

对桃树树冠上、中、下3层及东、西、南、北4个方位桃—点叶蝉及其天敌草间小黑蛛的系统调查分析表明，桃—点叶蝉及其天敌草间小黑蛛种群在7个部位的聚集强度其5个判断指数都大于聚集格局的判断标准，证明桃—点叶蝉及其天敌草间小黑蛛种群7个部位均为聚集格局，1wao公式m·=a+βx^-中的α值均大于0。表明个体间互相吸引，其中树冠中层和东面树冠平均拥挤度最高，而树冠下层和南面树冠最低，在时间上平均拥挤度为9月中旬最高．

Three-dimentional distribution pattern dynamics of Erythroneura sudra and its natural enemy Erigonidum graminicola

Investigations on the Erythroneur sudra and Erigonidum graminicola populations in three layers ( upper, middle and lower) and four directions (east, south, west and north) of peach tree crown showed that both of them had aggregated spatial distributions in these 7 part, because 5 parameters used to analyze the distribution reached required standard. Each insect was attracted by the others, as the parameter (a) in Iwao formulation m* = a +Bx-(1971) was positive. The average density of aggregation was the biggest in its middle layer and east direction, and the smallest in its lower layer and south direction . The biggest average density of aggregation appeared in mid-September.