Using different statistical tools to model spatial distribution of Adelphocoris lineolatus in alfalfa fields

This study aimed to model spatial distribution of alfalfa plant bug Adelphocoris lineolatus in six alfalfa fields during two growing seasons. Weekly sampling was started early in the spring and continued until cutting the hay. The plant bugs were sampled using six to eight 180° sweeps per 400 m2 grid and bugs captured by sweep net were counted. The data were analyzed using regression methods, dispersion indices and geostatistical analysis. According to the results, the variance to means ratio, dispersion indices (ID), David -Moore index (IDM), Lloyd’s index (x*) and Green's Index ( ) were greater than one, indicating the aggregated distribution. Regression statistics also showed that in all studied fields in the first and second year, distribution of the pest was aggregated and random, respectively. Due to the high coefficients of determination and the low standard error values of the regression coefficients, Taylor’s model was more efficient than Iowa’s model. The results of geostatistics confirmed the results of regression methods and distribution coefficients; and K index was less than 0.8 for 18 out of 20 datasets, which indicates the aggregated distribution. These results can be used in sampling and pest management programs of alfalfa plant bug.