Studies on Spatial Disiribution of Larvae of Leaf Miner,Phthorimaea operculella and Its Application

The aggregation indices and Taylors power law are used to test the spatial distribution of the third generation larvae of leaf miner in the tobacco fields.The results are as follows:The distribution pattern of larvae is aggregative (negative binomial distribution).The aggregation dose not change with the densities of population of leaf miner.The larvae are mainly aggregated distribution on the first stratification (four leaves) beneath tobacco plant;aggregated or random distribution on the second stratification;random distribution on the third stratification.Otherwise,the frequency of occurrence are used to estimate population densities of leaf miner.By comparing calculating population densities of the theoretical curves from Wilsons model and Gerrards model with practical one,it is found that the relationship between them is significant fit.But sampling estimating error of Gerrards model is less than that of Wilsons.Meanwhile,models of optimization sampling and sequential sampling are obtained by using Taylors parameters as follows:N=1.68857(t/D)2X-0.90661 and T(n)=(D/1.68857)-1.10301.n-0.10301