Number of Point Sources of Western Corn Rootworm (Coleoptera: Chrysomelidae) Eggs in Artificial Infestations Affects Larval Establishment and Plant Damage

Abstract

Abstract Host establishment of larvae of the western corn rootworm, Diabrotica virgifera virgifera LeConte, on a corn plant is approximately ten fold higher in artificial infestations in the greenhouse compared to artificial infestation in field experiments. We hypothesized that the paths that western corn rootworm larvae use to find their host from an individual point source (location where agar containing eggs is injected into the soil) in artificial infestations in the field may be limited and become obstructed by early hatching larvae. To evaluate our hypothesis, we tested two infestation levels (400 or 800 eggs/plant) each with five infestation patterns (1, 2, 4, 8, or 16 infestation points around the plant). An effect of infestation pattern was observed. Root damage on the 0 to 3 scale from an infestation of 400 viable western corn rootworm eggs increased significantly from 0.12 ± 0.03 to 0.74 ± 0.23 when the number of infestation points around the plant was increased from 1 to 16 at one location. R...