Ground Beetle Species (Carabidae, Coleoptera) Activity and Richness in Relation To Crop Type, Fertility Management and Crop Protection in a Farm Management Comparison Trial

Abstract

Ground beetle activity and species richness was monitored using pitfall traps in a plot trial system on a farm in northern England where the effects of organic and conventional fertility and crop protection management were separated within different crop types between 2005 and 2008. As well as analyses on species activity the beetles were split into small, medium-sized and large groups, and into groups of herbivores and specific Collembola feeders. Crop type had significant effects on the activity of the 20 most abundant species and all groups, generally with most in beans and winter barley and least in vegetables and spring barley. Most significant reactions to crop protection and fertility management were in cereals and grass/clover. Activity of small species was highest in conventionally crop-protected cereals but not in vegetables, with more medium-sized and herbivorous species in organic plots, but there was little influence of crop protection management on large and Collembola feeding species. However, large species were significantly more active in organically fertilised cereals and grass/clover, but not in vegetables, and there were more Collembola feeders in conventional cereals but not in grass/clover. Small species were more abundant in conventionally fertilised grass/clover but there were more in organic cereals and vegetables. These inconsistent activity reactions to management were also observed with individual species but most preferred organically managed plots. There were few significant crop protection : fertility management interactions. Species richness was also significantly affected by crop type and where management had an influence, more species were found in organically managed plots. Constrained ordination emphasised that ground beetle activity was influenced more by crops than by management. Given the diverse nature of organic crop rotations, crop type should be considered a major influence in any environmental manipulation aimed at increasing ground beetle activity for provision of ecosystem services.