Biodiversity of the ground beetles (Coleoptera: Carabidae) in orchard ecosystems of Azadshahr region, Golestan province, Iran

The coleopteran family Carabidae is one of the most abundant and diverse generalist predators in agroecosystems، playing an important role in maintaining pest populations below economic threshold. Using pitfall traps، carabid beetle specimens were collected from olive، peach، and mixed peach-olive orchards in Azadshahr region، east of Golestan province in 2009-2010. Two indices of Shannon-Weaver and Margalef were employed to evaluate the diversity and structure of the beetle communities. The species richness of ground beetles was 31، 19، and 12 species in mixed olive-peach، peach، and olive orchards; and the dominant species were Harpalus rufipes (De Geer)، H. rufipes and Calathus peltatus Kolenati، respectively. The values of Brillouin’s index of evenness and Shannon’s index of diversity were calculated as 0. 46 ± 0. 04، 0. 51 ± 0. 07، 0. 65 ± 0. 13 and 1. 59 ± 0. 18، 1. 52 ± 0. 21، 1. 57 ± 0. 23، respectively. There was no significant difference in overall Shannon’s indices، but the evenness of ground beetles in olive orchards was significantly higher than other orchards. The community of ground beetles on orchard margins was found to be more diverse than central parts. The high diversity of ground beetles in orchards of this region underlines their role in protecting the diversity of vegetations around or within the orchards and also efficiently keeping the populations of economic orchard pests in check throughout the season.