Spring wheat in Minnesota frequently harbors an assemblage of ground dwelling generalist predators, including ground beetles (Coleoptera: Carabidae) and spiders. Collembola and other detritivores may be an important food source for many of these predators, and several studies have suggested that supplementation of the detrital resource base results in increases in both detritivore and predator densities. Similar to previous research, I tested the hypothesis that addition of decaying organic matter to the soil will result in increased densities of collembola, which could subsequently lead to higher densities of ground dwelling predators in wheat. Experimental plots were established in a field of hard red spring wheat (Triticum aestivum) located at the Minnesota Agricultural Experiment Station, St. Paul, MN. Several treatments consisting of straw and alfalfa, chopped mushrooms and potatoes, or composted manure, were added to the plots early in the growing season. Soil arthropod activity was measured using pitfall traps. Slight increases in collembola activity were evident in all of the treatment plots at different times during the growing season compared with the control, but were particularly high in the mushroom and potato treatment. Slight increases in the activity of ground beetles and spiders were also seen in the mushroom and potato, and straw and alfalfa treatments, but most of these results were not statistically significant. These results support the hypothesis that increased resource availability results in increased detritivore activity, and possibly leads to higher predator densities.
Keywords: Carabidae, Collembola
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