The spatial distribution pattern of immature stages of the tomato fruit-worm Helicoverpa armigera (Lep.: Noctuidae) in Gorgan district

tomato pests, such as tomato fruitworm, Helicoverpa armigera Hünber (Hym.Eurytomidae), cause high reduction in tomato production, but no sampling program for population estimate and management of them has been developed. Spatial distribution of immature stages of the tomato Fruit-worm was determined by fitting data to either taylor’s, iwao’s, mean_variance ratio, k and morisita calculating dispersion indices, during 2008 and 2009 growing seasons in tomato fields of Gorgan, Spatial distribution immature (egg and larvae) is a random. Based on R2 and p-values of regression analysis, for most of the natural enemy groups, Taylor’s power law generally provided a more adequate description of variance/mean relationships than Iwao’s patchiness regression model. The median part of plant were fitted most value of Taylor’s b index. Percentage fit of immature stages the dispersion more random ratio bionominal value of morisita, k and mean-variance.