Geostatistical characteristics of the spatial distribution of the infestation pods by the pod borer, Heliothis viriplaca Huf. (Lep.: Noctuidae) in rain-fed chickpea (Cicer arietinum L.) fields in Delfan

Today different geostatistical techniques being widely used to predict the spatial variations of the pests. The pod borer، Heliothis viriplaca Huf. is the most important pest of chickpea، Cicer arietinum L. in the west areas of Iran. In this study in order to achieve the goal of Site Specific Integrated Pest Management (SSIPM) to reduce the application of chemical insecticides، geostatistical characteristics of the infestation pods by pest were studied in Delfan (Golestane & Dehsefied villages). For this، two chickpea fields (variety Bunij of Kermanshah) each about 2 hectares، were chosen. In each field، 88 points or stations with the certain coordination were marked، and in each station، 3 plants were chosen as sample unit، then the number of infested pods was determined. After data normalization، they were analyzed using Gs+ version 5. 1. Semivariograms were calculated to model the change in spatial correlation with increasing distance between samples. Results showed that the spatial distribution of the pods infestation by H. viriplaca was described by an exponential model for five out of eight data sets، a spherical model for two out of eight data sets. One data set was fitted to any model due to pure nugget effect. The range of spatial dependence varied from 311 to 933 m، and the degree of spatial dependence (DD= C/(C0+C)) varied from 0. 501 to 0. 547.