【摘要】 灰飞虱(Laodelphax striatellus Falln)近年来严重危害水稻并传播病毒病,麦田是其越冬并虫量扩增后向稻田迁移的重要场所,麦田一代灰飞虱也是防治的重点对象之一。利用半方差函数模型分析了麦田一代灰飞虱若虫在时间序列上的空间结构,得出了空间自相关的各项属性与虫口密度或环境因素的关系:长、短变程与密度无关,保持相对稳定;块金常数与密度成正相关(比例效应的存在),随机性强度与密度成三次多项式曲线相关;各向异性主要由于麦田行株距的差别所决定。并用一般克立金方法作出预测表面图,按时间顺序排列,将灰飞虱若虫在田间的时空分布情况直观地显示出来进行比较分析,得出灰飞虱若虫具有比较稳定的时空分布,认为食料充足、生境孤立、自身行动力较弱是形成这种情况的主要原因,此外包括天敌在内的一些次要因素也对其种群分布产生影响。更多还原

【Abstract】 The small brown plant hopper(SBPH),Laodelphax striatellus Fallén becomes an important pest of rice plant since it causes server damage by direct feeding and transmits virus disease recent years.Results from field surveys show that winter wheat field is an important place for overwintering,and multiplication of spring population of SBPH.The more important is the population of SBPH in winter wheat field supplied the SBPH source to disperse to rice fields.To better understand the population development and to improve the field sampling and chemical spraying strategy,we investigated the spatio-temporal dynamics of the first generation larvae of SBPH in winter wheat field.We analyzed the spatial structures of the first generation larvae of SBPH in the time series by using the geostatistical methods.To fit the semivariogram models for the every instars of the larvae in the wheat field,the spherical model and the Gaussian model were best for the most situations while only a few datasets best fitted the hole effect and the exponential model.We analyzed the relations between the characteristics indices of the semivariograms and ecological meaning of the larval density or environment factors.There were no significant correlation between one of the indices,"the major/minor range" and the density of SBPH.Both ranges kept relatively constant;The "nugget" was positively correlated with the density because a proportional effect existed between them.Furthermore,we calculated an indices "random strength" from the nugget to sill ratio for the semivariograms to correct the proportional effect and to provide a more accurate view of the spatial variability structure.We found the correlation between the random strength and the density fitted a cubic polynominal curve.Obvious anisotropy appeared in most datasets,and it likely due to the difference of plant spacing and row spacing.We drawn the predicted surface maps with the Ordinary Kriging method and illustrated in the time order to provide a visible presentation of the spatio-temporal distribution of the larval SBPH population.By analyzing those maps,we found that the spatial distribution of larval SBPH was very stable over time,most probably,due to the sufficient food、the insular habitation and the weak movement ability.In addition,factors such as predators in the field also affected the distribution of the larval SBPH population.更多还原