小麦田地下害虫幼虫的空间分布型与抽样技术

Spatial distribution pattern and sampling technique of the larvae of subterranean pest insects in wheat fields

为明确山西省南部小麦田地下害虫的空间分布型及抽样技术,采用连片调查法对小麦田地下害虫种群进行系统调查,通过5个聚集度指标、m^(*)-m回归模型和Taylor幂法则对其不同种群空间分布型进行分析,利用聚集均数分析其聚集原因,确定其理论抽样数和序贯抽样模型。结果表明,小麦田地下害虫混合种群、蛴螬和蝼蛄的聚集度指标扩散系数C>1,丛生指数I>0,负二项分布K值>0,久野指数C_(A)>1,聚块指数m^(*)/x^(-)>1,空间分布型均表现为聚集分布。金针虫的1组数据所有指标均不符合聚集分布,其余符合聚集分布。由m^(*)-m回归模型和Taylor幂法则拟合模型得出小麦田地下害虫混合种群、蛴螬和金针虫的空间分布型为聚集分布,聚集度依赖于种群密度,且聚集程度随着种群密度的升高而升高。混合种群、金针虫和蝼蛄的种群个体间相互排斥,基本成分为单个个体(α<0、β>1),而蛴螬种群基本成分是个体群,个体间相互吸引(α>0、β>1);聚集原因随种群密度而变化。经Iwao方法分析,当允许误差D为0.3,地下害虫混合种群、蛴螬种群和金针虫种群的虫口密度均为4头/m^(2)时,所需的理论抽样数分别为44、26和114 m^(2)。

In order to clarify the spatial distribution pattern and sampling technique of the subterranean pests in wheat fields in southern Shanxi Province,the population of the subterranean pests was systematically investigated,and the spatial distribution patterns of different populations were analyzed by using five aggregation indexes,m^(*)-m regression model and Taylor’s power law.The reasons for aggregation were analyzed by aggregation mean,and the optimum sampling number and sequential sampling model were determined.The results showed that the spatial distribution patterns of the mixed population of subterranean pests,white grubs and mole cricket belonged to aggregated distribution,with the diffusion coefficient C>1,the clumping index I>0,the negative binomial distribution parameter K>0,the Kuno index CA>1 and the patchiness index m^(*)/x^(-)>1.However,all the indexes for one group of data of the wireworms did not conform to the aggregation distribution,and the rest was in accordance with the aggregation distribution.Based on the parameters of m^(*)-m regression model and Taylor’s power law,the spatial distribution patterns of the mixed population of subterranean pests,white grubs and wireworms in wheat fields belonged to aggregated distribution;the aggregation degree depended on the density,and the aggregation degree increased with increasing population density.The fundamental components of the aggregation of the mixed population of subterranean pests,wireworms and mole cricket were individuals that were mutually exclusive(α<0,β>1),while the fundamental components of the white grubs were colonies by mutual attraction(α>0,β>1).The reasons for aggregation varied with the population density.The optimum sampling numbers for the mixed populations of subterranean pests,white grubs and wireworms under different error rates and population densities were determined by using Iwao’s method:when the permissible error D was 0.3 and their population densities were 4 larvae/m^(2),the optimum sampling numbers were 44 m^(2),26 m^(2) and 114 m^(2),respectively.