Spatial distribution of leafhopper Empoasca kraemeriRoss & Moore (Hemiptera: Cicadelidae) in cowpea and calculation of number of samples

Th objective was to study the spatial dispersion of the leafhopper Empoasca kraemeri Ross & Moore (Hemiptera: Cicadelidae) on culture of cowpea Vigna unguiculata (L.) Walp. and to establish the number of sample necessary to estimate the population of the pest for use in integrated pest management programs. Two experimental fields were cultivated at the Federal University of Ceará, in Fortaleza, Brazil. The area of the Field I was 216 m2, composed of 15 plots. The area of the Field II was 576 m2, divided into 25 plots. The cultivar used was Vita 7 with plants spaced 0.25 x 0.8 m. We performed three separate collections of data in Field I and four in Field II; in each plot ten plants were assessed. Th number of leafhopper nymphs and adults present in the plant was counted. The aggregate indexes used indicate that the dispersion of E. kraemeri in the fi is of the aggregate type, which was confirmed by fi the data to the negative binomial frequency distribution. To be used in integrated pest management programs, 30 is the sample number statistically suitable for the estimation of E. kraemeri population in V. unguiculata fields.

本研究旨在探究假眼小绿叶蝉（Empoasca kraemeri Ross & Moore，半翅目Hemiptera：叶蝉科Cicadelidae）在豇豆（Vigna unguiculata (L.) Walp.）栽培田中的空间分布格局，并确定用于该害虫种群估测的最优样本量，以支撑害虫综合治理项目的实施。试验于巴西福塔莱萨市塞阿拉联邦大学的两块试验田中开展。试验田I面积为216 m²，划分为15个样区；试验田II面积为576 m²，划分为25个样区。供试豇豆品种为Vita 7，植株种植规格为0.25×0.8 m。试验田I共开展3次独立数据采集，试验田II则开展4次；每个样区内选取10株植株进行调查，统计每株植株上假眼小绿叶蝉的若虫与成虫数量。所用的聚集性指数表明，假眼小绿叶蝉在田间的分布呈聚集型，该结果通过负二项分布（negative binomial frequency distribution）拟合试验数据得到验证。针对该害虫的综合治理项目，估测豇豆田假眼小绿叶蝉种群时，经统计学计算，最优样本量为30个样区单元。