Dispersion pattern and fixed precision sequential sampling of Sitobion avenae (Fabricus) (Hemiptera: Aphididae) in wheat fields of Badjgah (Fars province) in Iran

Understanding the dispersion pattern of a species is an important pre-requisite for developing an effective pest management program. In this study, four hundred wheat plants were surveyed for Sitobion avenae twice a week during 2010 and 2011 growing seasons in two fields of Badjgah (Fars province) in Iran. In each field only one of the two cultivers of Bahar or Shiraz was planted. Analysis of spatial distribution pattern using Taylor’s power law and Iwao’s regression model showed that S. avenae exhibited an aggregated distribution on wheat. Taylor’s power law was estimated from 84 data sets and fitted the data better than Iwao’s regression model. The optimal sample sizes needed for fixed precision levels of 0.25 and 0.30 were estimated using Taylor’s regression coefficients, and the required sample sizes increased dramatically with increased levels of precision. Therefore, the samplingplan we presented here should be used as a tool for an efficient estimation of S. avenae population density in wheat fields for pest management decision.