Spatial variability of sunn pest Eurygaster integriceps on Astragallus sp. in overwintering sites using GIS and geostatistical methods

       Study of Sunn pest Eurygaster integriceps population changes in overwintering sites on milkvetvh can be important in study of population dynamics and biological control. Many studies have been conducted on Sunn pest population in over wintering sites but data collection hasn't done for spatial analysis. In this study, spatial distribution of sunn pest population in overwintering sites was prepared by investigating 900 sampling points. These areas are within the maximum flight range of this pest. Geostatistical method of Inverse Distance Weighting (IDW) were used for mapping spatial variations of sunn pest. The results showed that the most important condition for pest in outbreak regions, are wheat and barley farms and the mountains with suitable cover crop near the farms for over wintering and it is one of the important indicator for sampling of Sunn pest population. Prevailing wind speed average was 13.6 knots and prevailing wind direction is south. Most of sunn pest density has been seen in the range of 1850 to 1650 meters above sea level elevation, slope 16 to 24 degrees and the northern slope. Regarding to the establishment of plantation in southeast highlands, sunn pest flights for overwintering, is done from fields to the mountains in the north to the south. It was also found that there is coordination between sunn pest flight and wind direction. The study of geostatistiucs methods showed that the Inverse Distance Weighting had less error and deviation (0.01 and 0.03) than cokriging and kriging methods. Using this method the spatial variations map of Sunn pest population was prepared.