Control ofAgrotis segetum [Lep.: Noctuidae] root crops by granulosis virus

Abstract

Agrotis segetumSchiff. granulosis virus (GV) propagated in Danish laboratory cultures was applied against field populations ofA. segetum in experimental latin square plots planted with beetroots, carrots and potatoes. Some test plots were isolated by net tents extending 15 cm into the soil whereas others were not caged. Plots were treated with suspensions of GV containing 106 to 108 capsules per ml with 50 ml being applied per m2 of plot. In 4 tests in which released eggs or larvae were caged over plots, cutworm numbers and damage were reduced by approximately 80% compared to untreated plots. The comparable reductions in 3 open experiments with natural populations of cutworms were 65–75%. GV-treatment 4 days after release of eggs appeared to be more effective than treatment 10 days after release. Whereas treatments with 107 and 108 capsules per ml reduced damages to approximately 75%, the effect of 106 Capsules was only 50%.