A Study on the Spatial Distribution Pattern of Dioryctria rubble

Dioryctria rubble is the major pest which damages the cones and seeds of Pinus armandii.It's spatial distribution pattern was examined by several aggregation indices,and regression analysis methods of Iwao,Talor and Lan Xinping etc.The results show that the spatial distribution pattern of the overwintering larvae belong to the aggregation distribution,and the aggregation are caused by both the insect's biological characteristics and the environmental factors.Among the regression analysis,the linear related degree of the La-m regression model is the optimum while the other three models also fit well.