Invertebrate community composition in dominant agroecosystems of Saskatchewan, Manitoba, and North Dakota

Agriculture currently occupies the majority of the former prairie ecosystem of North America, and farm management decisions affect the abundance and diversity of life in this region. Over 3 yr, we collected and identified the aboveground and soil insect communities from 159 agricultural fields representing 16 different food systems. A total of 107,320 specimens representing 990 operational taxonomic units were collected and identified. The invertebrate community was represented by 24 Orders, 189 Families, and 477 identified Genera. Herbivores were the most abundant (26,112 specimens; 59% of the non-Collembola/mite specimens) and taxonomically rich (308 species; 31%) functional group. Parasitoids, predators, omnivores, and detritivores were each represented by 8% to 10% of specimens collected. Perennial grassland habitats had the most abundant and diverse invertebrate communities (528 insects from 79 species per field); which was approximately twice that of any monocropped system. Including a second cash crop (ie intercropping) often doubled the insect community abundance and richness (380 specimens, 64 species) relative to the component monocrops. This research suggests that conservation and promotion of invertebrate biodiversity within agricultural landscapes may be fostered by supporting perennial grazing lands and intercropping as an alternative to monocrop farming.