Harboring Beneficial Insects

Harboring Beneficials Reduces Chemicals

Researchers search for ground beetles, beneficial insects that are attracted to vegetative refuge strips in crop fields. Photo by Bob Neumann

Tilling, planting, cultivating and harvesting on farms can kill off beneficial insects that prey on crop pests. SARE-funded researchers in Michigan have identified ways for growers to retain or create undisturbed areas on farms to harbor beneficial insects that will help keep pest populations in check and reduce the need for synthetic pesticides. Beneficials flock to vegetative strips, particularly strips of switchgrass—a native, warm-season grass with tall, stiff stems. It contained 38 species of ground beetles, which not only prey on insect pests, but ingest many types of weed seeds as well. The beetles destroyed 84 percent of foxtail, a pervasive weed, in one week alone in the switchgrass strips versus only 17 percent in the soybean field far away. They also found refuge strips of orchard grass, clovers and perennial flowering plants sheltered greater numbers of beetles in winter than a control area. A cooperating farmer who uses filter strips stopped spraying insecticides in his field, saving $6 to $10 per acre. Researchers next will study how well the beetles migrate into crop fields to seek food after overwintering in refuge strips. (LNC95-85)

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