Ground beetles (Coleoptera, Carabidae) in an intensively managed vegetable crop landscape in eastern England

Four fields (three organic and one conventionally managed) in an intensive vegetable producing landscape in eastern England were sampled for ground beetles in 2005 and 2006, using pitfall traps, to investigate species activity and species assemblage distribution within five crop and three field margin types. In addition, non-crop ditch sites were also sampled. Three species assemblages in the fields were strongly related to crop type, with two others consisting of non-crop sites, one dominated by field margins, the other by ditch sites, Species activity and richness in fields were also strongly, and significantly, associated with crop type, with most in organic Brassica crops (cauliflower, cabbage, broccoli), less in organic leeks and least in conventional calabrese. Some species were significantly more active in weedier fields but others preferred more open ground. Considerably more species were recorded from first-year planted field margins, with fewest species active in unplanted margins. Activity was also relatively low in densely vegetated second-year margins. There appeared to be little relationship between species activity in the margins and that in the crop fields. Ground beetle species are important for the predation of cabbage root fly eggs in Brassica Crops, especially in organic fields. In order to enhance and maximise appropriate ground beetle species activity and predation within vegetable fields, it is likely that management within both fields and margins would be required, as well as some method for increasing movement of predators from margins into fields. (C) 2009 Elsevier B.V. All rights reserved,