Fixed Precision Sequential Sampling Plan Using Sweep Net to Estimate of Population Density of Sunn Pest) Eurygaster integriceps Put.) in Rainfed Fields of Wheat in Borujerd

Sunn Pest, Eurygaster integriceps Put. is the most important pest of wheat and barley in Borujerd, north of Lorestan province, Iran. The most commonly employed methods of sampling for this pest are the use of quadrate (absolute estimate) and sweep net (relative estimate). Sweeping is the most convenient sampling method for many arthropods. In this research, spatial distribution and Green’s sequential sampling plan were investigated using a standard sweep net to estimate of population density of sunn pest in rainfed fields of wheat in Borujerd during 2004-2005. Results show that, Taylor's Power Law regression model, provided a more adequate description of variance-mean relationships for sweep net. Taylor's was significantly >1, indicating that nymph stages and new generation adult sunn pest population were aggregated in rainfed fields of wheat. Green's fixed-precision sequential sampling plans were designed for estimating 3rd, 4th nymph instars and 5th nymph instar + new generation adult at three fixed precision levels (0.1, 0.15 and 0.25). These models were validated using 11-13 independent data sets ranging in density 0.4-6.92, 0.91-30 and 0.34-24.21 individual per sample, respectively. To achieve a precision of 0.25 which is generally accepted in IPM programs, it is necessary to take an average sample number (ASN) of 23, 22 and 35, respectively. As the precision level was increased to 0.10, ASN increased to 166, 127 and 190 in above mentioned stages, respectively. Therefore, Green’s fixed precision sequential sampling plan using sweep net, was the most preferred and convenient method to monitoring of nymph instars and new generation adults of E. integriceps in rainfed fields of wheat.