甘薯大象甲幼虫的空间格局研究

Spatial Distribution Pattern of Mecyslobus roelofis Larva

为了明确甘薯大象甲幼虫的空间分布和种群特征。2011年通过对15块甘薯田的调查,应用聚集度指标的计算公式和Iwao的m*-m回归分析法、Taylor的幂法则等,对其空间分布型和田间理论抽样数进行了测定和分析。结果表明:甘薯大象甲幼虫在甘薯田间呈聚集分布。聚集强度与密度相关,聚集强度随着幼虫密度的升高而增强;而个体群所占的空间随密度的升高而减少。导致甘薯大象甲幼虫聚集分布的主要原因是环境因子。在此基础上,建立了幼虫虫口密度调查的最适理论抽样数公式[n=1.962/D2(1.1047/m+0.8737)]和序贯抽样模型[T0(n)=0.2n±0.4759]。

In order to find out the distribution and occurrence law of Mecyslobus roelot^s larvae in sweet potato fields, the spatial distribution pattern and theoretical sampling frequency were investigated and analyzed in 2011, using related aggregation index formulae, Taylor＇ s power law and Iwao＇ s m＊-m model. The results showed that, the spatial pattern of Mecyslobus roelotTs larvae belonged to assemble distribution in sweet potato fields. The aggregating intensity of Meeyslobus roelot^s larvae increased with the population density, but the space of the colony became smaller. The larva＇ s aggregation in sweet potato fields was due to environmental factors. Base on the data of spatial distribution, the optimum theoretical sampling number of the larva could be obtain from the formula [n=I.gC//Y （1.1047/m ＋ 0.8737）] and Iwao＇ s model [T0（n）=0.2n 0.4759 n] of sequential sampling.