Trap cropping to manage the red sunflower seed weevil in oilseed sunflower

Abstract

AbstractThe red sunflower seed weevil,Smicronyx fulvusLeConte, is a major pest of sunflower in North and South Dakota and Minnesota. Typically, insecticides are used to reduce oviposition and prevent economically damaging larval populations from developing. In a test of a reduced-pesticide alternative, we planted early maturing sunflower in the margins around commercial fields of oilseed sunflower. The margins flowered earlier than the field interiors and acted as a trap for the red sunflower seed weevil. They were treated with an insecticide while the trap rows were blooming and before the field interior began to flower. Conventional fields entirely treated with insecticide served as checks. We compared the trap and check fields with regard to yield, the fraction of larval-damaged seeds, and economic costs (insect damage and the cost of insecticide materials and application). Yield and larval damage of seeds were comparable between check and trap fields. However, the economic costs of weevil control in the check fields was greater than in the trap fields. Trap cropping is a recommended strategy for the red sunflower seed weevil, especially where economically damaging populations of the weevil are expected.