Effects of Strip Intercropping and No-Tillage on Some Pests and Beneficial Invertebrates of Corn in Ohio

We tested two agronomic practices that are likely to increase plant and structural diversity, no-tillage and strip intercropping, for effects on corn invertebrate fauna. Some of the most common herbivores and natural enemies were sampled by direct counts and damage estimation from 1988 through 1990 on monoculture corn and strips of corn alternated with soybean, under no-tillage and conventional tillage. Among soil pests, cutworms (mostly the black cutworm, Agrotis ipsilon (Hufnagel)); armyworm, Pseudaletia unipuncta (Haworth); and slugs (Gastropoda) were more abundant in no-tillage plots, although only slugs caused severe damage. The western corn rootworm, Diabrotica virgifera virgifera LeConte, and the European corn borer, Ostrinia nubilalis (Hübner), were generally more abundant in conventional tillage plots. Despite crop rotation, the strip-intercropping system (four rows of each crop) was less effective in reducing western corn rootworm infestation, especially in conventional tillage plots. In 1990 only, ladybugs (mostly Coleomegilla maculata (DeGeer)) were more abundant in conventional tillage plots, whereas tarnished plant bugs, Lygus lineolaris (Palisot de Beauvois), were more abundant in notillage plots. Japanese beetle, Popillia japonica Newman; stink bugs, Acrosternum hilare (Say) and Euschistus servus (Say); and spiders (Aranea) were not significantly affected by treatments.