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

Abstract

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.