Geostatistical Analysis on the Spatial Dstribution Characteristics of Batocera lineolata Larvae in Eucalypti Plantations

The spatial distribution characteristics of Batocera lineolata larvae population in the representative locations of eucalypti plantations from a local perspective and 98 locations of eucalypti plantations in 18 counties of Chongqing in a large scale were studied using geostatistics methods. The results showed that the population density and the spatial distribution characteristics of the 3 eucalyptus plantations with different damage degrees were obvious differences. The semi-variogram analysis indicated that Gaussian models, spherical models and spherical models were suitable for simulation of spatial distribution of BL larvae in slightly, moderately and heavily infested forests, respectively. These models indicated the distribution of the larvae in the 3 infested forests belong to aggregation type. The spatial dependence existed in the three infested forests, and the dependence is more obvious in the heavily infested forests. The spatial distribution pattern generated by the Kriging interpolation showed that BL larvae had intensive spatial aggregation in the three infested forests. In the large-scale view, there were significant differences in the BL larval population among these eucalypti plantations of different counties. Meanwhile, the zoning map and spatial distribution map of BL hazard degree obtained by inverse-distance weighting showed that the BL larvae was mainly moderately and severely harmful in these eucalypti plantations of the surveyed counties, and had a significant aggregation distribution, which is related to the existence of some high risk area of BL larvae. Traffic roads and tree distribution pattern of eucalypti plantations could be the key factors affecting the extensively spread and the spatial distribution characteristics of BL.