Spatial Distribution Patterns and Sampling Techniques of Overwintering Larvae of Cephalcia infumata-An Important Pest in Picea crassifolia
This study investigates the spatial distribution of the overwintering larvae of Cephalcia infumata in the soil to provide a scientific basis for its prediction and control.The spatial distribution pattern of the overwintering larvae was analyzed by using aggregation index method,Taylor's power law and Iwao's regression method.The theoretical number of overwintering larvae was determined based on the Iwao regression model,and the maximum theoretical sampling numbers under different permissible errors(D=0.1,0.2,0.3)and economic thresholds(=3,5,10 individuals/plant)were obtained through sequential sampling techniques.The results show that in the forest area of the Ningxia Luoshan Nature Reserve,Cephalcia infumata produces one generation per year,with overwintering larvae mainly distributed in the soil at depths of 0～10 cm.The larvae are more abundant on sunny slopes and show an aggregated distribution that fits the negative binomial distribution.The mean aggregation of the population shows a linear relationship with the average population density,and the intensity of aggregation increases with population density.Based on the Iwao regression model,at t=1.96,the maximum theoretical sampling numbers were 596,149 and 66 plants for =3 and D= 0.1,0.2,and 0.3,respectively;477,119 and 53 plants for =5 and D=0.1,0.2,and 0.3,respectively;and 388,97,and 43 plants for =10 and D=0.1,0.2,and 0.3,respectively.The spatial distribution pattern of Cephalcia infumata was aggregated,mainly occurring at the forest edge.The maximum sampling number determined by sequential sampling can be used to guide the monitoring and control of Cephalcia infumata.
万方数据
维普
