Movement of corn rootworm larvae (Coleoptera : Chrysomelidae) between border rows of soybean and corn in a strip intercropping system

Strip intercropping of corn may provide spatial and temporal diversity for management of extended-diapause corn rootworm populations. Strip-intercropp ed corn may sustain infestations of corn rootworm larvae attributable to mi gration of larvae into Ist-yr corn from soil previously planted to corn. Ro w-specific distribution of corn rootworm eggs and adult emergence were dete rmined in a strip intercropped system, and effects of interstrip cultural a nd insecticidal treatments on rootworm infestation of outer rows were evalu ated. Corn rootworm eggs were found in all rows of strips previously plante d to corn. Root injury ratings were significantly higher in the outer rows than in the interior rows of corn adjacent to the previous year's corn stri ps. Oilseed meal and insecticide treatments were associated with lower corn rootworm adult emergence and larval root injury than was found in untreate d plots. Higher rootworm adult emergence and root injury scores in tillage treatments, where the soil was disturbed by ripping with a cultivator shank , were attributed to increased soil pore space that facilitated larval move ment into adjacent corn strips. Fewer adults emerged and less root injury o ccurred in outer rows of corn adjacent to soybean strips that were subjecte d to interrow soil compaction from wheel traffic. In severely infested fiel ds, deliberate compaction of interrow soil or incorporation of cruciferous plant material into soil between strips are possible noninsecticidal manage ment options for reducing severe corn rootworm infestation of outside rows of corn in strip intercropping systems.