Occurrence and spatial distribution patterns of Curculio chinensis larvae

Based on the collected field data, the spatial distribution pattern of Curculio chinensis larvae was tested by 8 types of aggregation indices and 2 types of regression equations, the assembling causes were analyzed with average aggression size, the relationship between its occurrence and environment was analyzed by SPSS. The results showed that, the spatial distribution pattern of the larvae belonged to the aggregation distribution with density dependence. The basic component of larval population spatial distribution was a group of individuals, which attracted one another. The aggregation was caused by both pests biological characteristics and environmental factors. The population density of larvae was less affected by direction, but greater affected by height level. The harm of fruits by larvae was most serious at the lower layers, but less at the upper and middle layers.