桑树害虫黄星天牛幼虫的空间分布型与抽样技术

Spatial Distribution Patterns and Sampling Techniques of Mulberry Pest Psacothea hilaris Pascoe Larvae

黄星天牛Psacothea hilaris Pascoe是桑树的主要害虫之一。调查黄星天牛种群在云南省蒙自蚕区桑园的空间分布结构和建立相应的抽样技术,有利于对害虫的预测预报及制定防治策略。利用6种聚集度指标以及Taylor的幂法则、Iwao m*-m回归分析法建立的2种回归模型测定黄星天牛幼虫在桑树上呈聚集分布,分布的基本成分是个体群,个体间相互吸引且聚集度随着种群密度升高而增大。利用Blackith种群聚集均数(λ)解析幼虫种群的聚集因素主要由环境因素组成,如气候、食料、桑园周围种植的其他宿主植物等。根据Iwao m*-m回归关系建立了黄星天牛幼虫抽样数公式和序贯抽样模型,在田间应用该模型调查样本的累计虫口数量超过上限时,即判为需要实施防治措施。

Psacothea hilaris Pascoe is one of the major mulberry pests. Investigating the spatial distribution patterns and establishing the corresponding sampling techniques of P. hilaris population would facilitate the forecast,prevention and control of P. hilaris. In this study,the spatial distribution patterns of P. hilaris larvae on mulberry were studied by six aggregation indexes and two established regression equations based on Taylor＇s power law and Iwao m＊-m regression analysis. The results showed that P. hilaris larvae presented an aggregating distribution on mulberry trees,and the basic component of distribution was individual colony. P. hilaris individuals attracted each other and the aggregation intensity was increased with population density. Elucidation of average aggression size λ proposed by Blackith indicated that the factors influencing the aggregative distribution of P. hilaris larvae population were mainly composed of environmental factors such as climate,food,other host plants planted around mulberry fields and so on. Based on Iwao m＊-m regression analysis,the formula for calculating sampling number and sequential sampling model were constructed. When the accumulated number of investigation samples in field exceeds the upper limit,it is needed to implement control measures.