枣飞象成虫在陕北枣区的空间分布型及抽样技术

Spatial distribution of Scythropus yasumatsui adults and sampling techniques for this species in the Jujube growing region of Northern Shaanxi

【目的】枣飞象Scythropus yasumatsui Kono et Morimoto是枣树Ziziphus jujuba Mill主要害虫之一。近年来,枣飞象在陕北黄河沿岸枣树种植区暴发成灾,给陕北红枣产业造成了严重的经济损失。明确枣飞象成虫在陕北枣区的空间分布型及最佳抽样技术,为枣飞象的监测预报和有效防治提供理论依据。【方法】2015年于陕西省佳县枣区,首先选取具有代表性的枣树样地,采用五点抽样法、双对角线抽样法、棋盘式抽样法、平行线抽样法和Z形抽样法抽取受害枣树,随后采取分层取样法分别统计每株枣树上枣飞象成虫数量。采用t-检验对这5种抽样方法的适合性、代表性和变异程度进行了比较,确定最理想的抽样方法;随后用聚集度指标、Iwao m*-m回归分析法以及Taylor幂法则对枣飞象成虫在枣区的空间分布型进行了研究,选用Iwao提出的理论抽样公式和序贯抽样公式确定了枣飞象成虫的理论抽样数和序贯抽样模型。【结果】结果表明,5种抽样方法都适合枣飞象成虫在陕北枣园的调查,其中以平行线抽样方法最为理想,枣飞象成虫的空间分布型为聚集分布,分布的基本成分是个体间相互吸引的个体群,且个体群的聚集度与其成虫数量成正比,枣飞象个体群聚集原因是由于某些环境成分或者是本身聚集性活动中的一个因素或共同作用引起的。建立的理论抽样数公式为N=t^2/D^2(18.995/m+0.0203),序贯抽样模型为T0′, T0(n)″=30n±47.53√n。【结论】枣飞象成虫在田间最理想调查方法为平行线抽样法,枣飞象在陕北枣区成虫分布型呈聚集分布,为陕北枣区枣飞象的监测预报及可持续防治提供基础资料。

[Objectives] Scythropus yasumatsui Kono et Morimoto is one of the most important pests of jujube trees. In recent years, S. yasunatsui irruptions in the jujube growing region along the banks of the Yellow River in North Shaanxi have caused enormous economic losses to the jujube industry of this region. The aim of this research is to determine the spatial distribution pattern of S. yasumatsui adults in the region, and develop effective sampling techniques for this species, thereby providing a theoretical basis for more accurate monitoring, prediction and control of this pest.[Methods] We selected 5 representative jujube fields as sampling sites in Jia County in 2015, and evaluated five different sampling methods(five-point sampling, double diagonal sampling, chessboard sampling, parallel sampling lines and Z-shaped sampling). The number of adult weevils on each jujube tree was recorded using stratified sampling. The suitability, representativeness and variability of the five sampling methods were compared and analyzed using t-tests. The spatial distribution pattern of S. yasumatsui adults in the jujube region was studied using aggregation indices, Iwao’s m*-m regression analysis method and Taylor’s power law. The theoretical sampling number and a sequential sampling model for adult weevils was determined using Iwao’s theoretical sampling and sequential sampling formulae.[Results] All five sampling methods were effective but the parallel sampling method was the best. S. yasumatsui adults have an aggregated spatial distribution in the jujube growing region of Northern Shaanxi. The basic component of the distribution was a group of individuals;individuals attract each other so the greater the density the higher the degree of aggregation. The reason for this aggregation is either some environmental factors or an innate tendency of this weevil to aggregate. The optimum theoretical sampling model was N=t^2/D^2(18.995/m+0.020 3) and the optimum sequential sampling model was T0′, T0(n)″=30 n ±47.53√n.[Conclusion] The parallel line sampling method was the best for investigating the spatial distribution of S. yasumatsui adults,which was found to be aggregated. These results provide basic data for monitoring, predicting, and the effective and sustainable control of S. yasumatsui in the jujube growing region of Northern Shaanxi.