Sequential and binomial sampling models of Sipha elegans (del Guercio) (Hemiptera: Aphididae) in irrigated wheat fields in Miyaneh region, Iran

Spatial distribution of Sipha elegans as well as sequential and binomial sampling plans for estimating its population were studied in Miyaneh wheat fields, northwest of Iran. Sampling was carried out every three days by visiting 100 wheat stems and counting the aphids. Mean and variance of aphid population at sampling dates were used to estimate spatial distribution parameters. Regarding to better description of the data by Taylor's power law, parameters of this method were used to develop sequential and binomial sampling plans at both research and Integrated Pest Management (IPM) precision levels (0.1 and 0.25, respectively). S. elegans was observed in the field from early June to early July with aggregated spatial distribution. In sequential sampling model, sample size required to determine aphid mean population was decreased by increasing density and precision level from 0.1 to 0.25, for example, sample size required in mean density of one aphid per stem was decreased from 2138 stems at 0.1 to 324 stems at 0.25 precision level. Sample size was also smaller (342 stems) in binomial model than enumerative one (431 stems) at 0.25 precision level in the mentioned above aphid density. According to the results, sample size was enormous in both sequential and binomial models and at research precision level, but sequential and binomial sampling models at IPM precision level were recommended for determining S. elegans mean population because they reduce sampling time and cost in aphid’s integrated pest management programs.