烟草田间蛴螬种类及其空间分布与抽样技术研究

Species composition,spatial distribution pattern and sampling technique of white grubs in tobacco fields

【目的】明确烟草田间蛴螬类害虫的种类组成及种群空间分布特点,为蛴螬类害虫的预测预报及田间防控提供理论指导。【方法】于2015—2019年,以云南省大理州弥渡县红花大金元烟田为调查点,采用五点取样法对烟田中的蛴螬种类组成进行系统调查;利用Iwao回归法和Taylor幂函数法计算测定蛴螬混合种群的空间分布特征,并利用种群聚集均数分析蛴螬类害虫在田间的聚集原因;根据空间分布格局,模拟形成烟田蛴螬混合种群的抽样技术。【结果】云南省大理州弥渡县红花大金元烟田共发现5种蛴螬,隶属于3科5属,其中小黄鳃金龟(Metabolus flavescens Brenske)和铜绿丽金龟(Anomala corpulenta Motschulsky)是优势种,相对多度分别为33.09%和34.96%。蛴螬混合种群在红花大金元烟田中主要以个体群呈聚集分布,且聚集程度与密度呈正相关,但个体间相互排斥。聚集均数(λ)分析结果显示λ值均小于2,表明蛴螬在田间的聚集原因主要是由气候、土壤湿度和植株生长状况等环境因素引起。根据Iwao的m~*-m回归方程,建立了不同精度下蛴螬类害虫的理论抽样数和序贯抽样模型,当蛴螬防治标准为2头/株时,蛴螬田间的累积虫量高于上限指标(T1)即应采取防治措施。【结论】云南省大理州弥渡县烟区红花大金元烟田共有5种蛴螬混合发生,混合种群主要以个体群在田间呈聚集分布,聚集度依赖于密度,聚集原因主要由环境因素引起。

【Objective】The study aimed to clarify the species composition and spatial distribution characteristics of the white grubs in tobacco fields and provide theoretical basis for making forecast and integrated control of these pests.【Method】The investigations on the white grubs species in the fields of planting Honghuadajinyuan tobacco was carried out in Midu County of Dali Prefecture,Yunnan Province from 2015 to 2019,by using the 5-point sampling method and visual inspection.The spatial distribution pattern of the white grubs in soil was investigated and determined by using two regression models,including Iwao’s regression equation and Taylor’s power law,and the reasons for the aggregation of the larvae in the fields was analyzed by the aggregation mean.Finally,the optimum theoretical sampling model and sequential sampling techniques were established based on spatial distribution.【Result】There were five species of white grub belonging to three families and five genera in Honghuadajinyuan tobacco fields.The larvae of Metabolus flavescens Brenske and Anomala corpulenta Motschulsky were dominant species in soil of tobacco fields,whose relative abundances were 33.09%and 34.96%,respectively.The spatial distribution pattern of the grubs in Honghuadajinyuan tobacco fields belonged to aggregate distribution,and the basic component of spatial distribution was a group of individuals.There was a positive correlation between the aggregation degree and population density,but in larvae population,the individuals excluded each other.Results of the aggregation mean(λ)were all smaller than 2,indicating the reasons for aggregation were environmental factors such as climate,soil humidity and plant growth status.According to Iwao’s m*-m regression equation,theoretical sampling number and sequential sampling model was established under different accuracy degrees.It was necessary to take actions when the number of grubs in the field was more than the upper limit(T1)of accumulated grubs for sequential sampling with the economic threshold of two larvae per tobacco.【Conclusion】There are five species of white grub occurring in mixture in tobacco fields in Midu County,Dali Prefecture,Yunnan Province.The spatial pattern of the mixed population of white grubs is in an aggregate distribution.The aggregation degree is depended on the density and aggregation is caused by environmental factors.