Abstract

Illinois corn and soybean farmers have increased their use of cover crops, particularly winter cereals such as cereal rye (Secale cereale L.) and winter wheat (Triticum aestivum L.), as a conservation practice in recent years. Use of a winter cereal cover crop could impact the invertebrate fauna present within a field, including potentially both pest and beneficial species. We assessed insect and slug activity density and injury to the crop in field experiments planted to corn (Zea mays L.) and soybean (Glycine max (L.) Merrill) that had been established to study the impact of cover crops on agronomic management and nutrient loss reduction. A cereal rye cover crop resulted in marginal increases in ground beetle (Coleoptera: Carabidae) and spider (Araneae) activity and a slight decrease in early-season injury to soybean. Increased cover crop biomass associated with later termination timings resulted in higher spider activity densities. Slight increases in slug activity were associated with the latest termination of cover crops, but the effect was not consistent at the other termination timings. Neither cover crop presence nor termination timing affected injury to corn; however, in most cases the cover crop was terminated well before corn planting (≥3–4 weeks). Plant stand was not affected by cover crop treatment at any of our sites. Although care should be taken in drawing broad conclusions, cover crops had a relatively minor impact on economically important insects and other invertebrates in this experiment and reduced injury in one instance.