The Ichneumonidae, as one of the largest insect families, includes beneficial insects parasitizing 53 several pests. Due to geographic and climatic varability of Iran, a great Ichneumonidae diversity 54 may be expected, but our knowledge about fauna and biodiversity of this family in Iran is still 55 insufficient, with only a few sporadic biodiversity studies on Iranian ichneumonids. This paper 56 examines the alpha diversity, species evenness, species richness and beta diversity of the 57 Ichneumonid parasitoid wasp assemblages in Golestan Province, northeast Iran with an emphasis 58 on the two largest Ichneumonid subfamilies: Cryptinae and Ichneumoninae. The spatial diversity of 59 Ichneumonidae in two consecutive years was studied in three habitats: forest, rangeland and 60 orchards. A total of 336 specimens representing 62 genera and 97 species were collected and 61 identified. The forest sites (Shast kalate and Tuskestan) and rangeland sites (Chahar bagh and Souz 62 javal) were more diverse than orchard sites (Kordkuy and Garmabdasht), but the lowest species 63 evenness was observed in the latter. The highest species richness was found in rangeland, the 64 highest similarity between the two forest sites, and the lowest similarity between Kordkuy (orchard) 65 and Chaharbagh (rangeland). Of all individuals collected, 32.7% and 67.3% were female and male, 66 respectively. The species richness and abundance of parasitoid wasp species yielded from the 67 relatively small sample area indicate that there are many species in Iran that still remain to be 68 discovered. In total, the use of parasitoid Hymenoptera, as potential bioindicators, provide a useful 69 and practicable monitoring tool for tracking and evaluating changes in various ecosystems and 70 reflecting environmental conditions.

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