沙冬青豆荚螟天敌空间分布的地统计学分析

Geostatistical analysis of the spatial distribution of Etiella zinckenella larvae and their natural enemies on Ammopiptanthus mongolicus

空间分布格局是昆虫种群的重要属性。沙冬青是我国重点保护的珍稀濒危植物,豆荚螟是为害沙冬青种子的主要害虫,研究种子害虫及其天敌的区域性空间分布格局是害虫宏观管理的前提和基础。地统计学是深入研究昆虫种群空间格局的有效方法。2018年5月-6月,选择宁夏灵武白芨滩国家级自然保护区内沙冬青分布片区,采用地统计学方法,分析了沙冬青种子害虫豆荚螟幼虫及其天敌的空间分布格局。结果显示沙冬青有虫株率为100%,豆荚受害率为23.02%,豆粒受害率为14.11%;沙冬青豆荚螟幼虫的密度为(0.2969±0.0020)头/荚,寄生性天敌密度为(0.0120±0.0002)头/荚。分别采用不同的理论模型来拟合豆荚螟幼虫及其天敌的空间半变异函数曲线,其全方向半变异函数曲线最优模型分别为高斯模型和球面模型,空间格局均呈聚集分布;害虫和天敌存在一定空间相关性,空间依赖范围分别为88.61~434.05 m和159.05~426.88 m。用Kriging空间插值法对害虫和天敌的空间分布进行模拟,结果呈斑块状分布,二者存在空间依赖性和互补性。天敌对害虫有一定的空间跟随效应和控制效应。

The spatial variation of insect populations is caused by the interactions between population dynamics on one hand and biotic or abiotic factors on the other.Spatial distribution pattern is an important attribute of insect population.Ammopiptanthus mongolicus is a rare and endangered plant in China,and Etiella zinckenella is one of the main seed pests of A.mongolicus.Understanding the spatial distribution pattern of seed pests and their natural enemies is the premise and basis for integrated pest management.Geostatistics is an effective method for studying the spatial distribution pattern of insect populations.From May to June 2018,we selected a sample plot of A.mongolicus in Lingwu Baijitan National Nature Reserve of Ningxia,and analyzed the spatial characteristics of the population spatial structure of E.zinckenella larvae and their natural enemies by using geostatistical method.The results showed that each plant of A.mongolicus was damaged by seed pests;the damage rate of pods was 23.02%,and the damage rate of beans was 14.11%.The density of E.zinckenella larvae was(0.2969±0.0020)per pod and the density of natural enemies was(0.0120±0.0002)per pod.The best models for E.zinckenella larvae and their natural enemies were Gauss model and Spherical model;the semi-variogram curve and spatial distribution were fitted by these two models,respectively.The spatial pattern of pests and their natural enemies were aggregated distribution.There was a spatial correlation between the pest and their natural enemies to a certain degree.Analysis of the isotropic variogram indicated that the distance of spatial dependence of the pest and its natural enemies were 88.61-434.05 m and 159.05-426.88 m,respectively.The spatial distribution of pests and their natural enemies was simulated by using Kriging spatial interpolation method.The results showed that the spatial distribution was patchy and there was spatial dependence and complementarity between them.Natural enemies of the pest had a spatial following effect and controlling effect on the pest to a certain degree.