玉米田四代棉铃虫老熟幼虫空间分布型应用

Spatial Distribution Pattern Application of Fourth-Generation Mature Larvae of Cotton Bollworm (Helicoverpa armigera Hübner) in Maize Field

[目的]研究玉米田四代棉铃虫老熟幼虫空间分布型。[方法]于2009年8～9月,对第4代棉铃虫不同发生密度地块进行调查,取得了6组样本资料,应用聚集度指标法、Iwao法和Taylor法等7种指标分析,对其空间分布型进行检验。[结果]聚集度指标的检验结果表明:所有样地Moore I<0,Lloyod m/m<1,Kuno Ca<0,扩散系数C<1,扩散型指数Iδ<1,负二项分布,K<0,表明棉铃虫老熟幼虫在夏玉米上均呈均匀分布。棉铃虫第4代老熟幼虫在夏玉米上的Iwao回归方程为m=0.0906+0.7669m,r=0.9863;说明棉铃虫分布的基本成分为单个个体,老熟幼虫在夏玉米上呈均匀分布。利用公式N1=(1.0906/m-0.2331)/D2即可求出棉铃虫第4代老熟幼虫在玉米上不同密度下的最适抽样数。[结论]研究结果为准确估值棉铃虫种群数量及变动规律,为预测及防治棉铃虫提供依据。

[Objective]The paper was to study the spatial distribution pattern of fourth-generation mature larvae of cotton bollworm in maize field.[Method]The plots with different occurrence densities of fourth-generation cotton bollworm were investigated during August to September in 2009.Six groups of sampling data were obtained,and seven indicators were used to determined its spatial distribution pattern.including aggregation index method,Iwao method and Taylor method,etc.[Result] Aggregation index test showed that in all plots,Moore I 〈 0,Lloyod m＊ /m 〈 1,Kuno Ca 〈 0,diffusion coefficient C 〈 1,diffusion index Iδ 〈 1,negative binomial distribution K 〈 0,indicating that mature larvae of cotton bollworm showed uniform distribution in summer maize.Iwao regression equation of fourth-generation mature larvae of cotton bollworm in summer maize was m＊ = 0.090 6 ＋ 0.766 9m,r = 0.986 3,indicating that the basic components of cotton bollworm distribution was single individual,and mature larvae of cotton bollworm in summer maize showed uniform distribution.The optimal sampling number of fourth-generation mature larvae of cotton bollworm in maize under different population densities could be calculated using formula N1 =（1.090 6/m-0.233 1） /D2.[Conclusion]The result provided basis for accurate evaluation of population quantities and variation law of cotton bollworm,as well as prediction and control of the pest.