Host suitability and feeding preference of the grapevine pest (Abagrotis orbis) (Lepidoptera: Noctuidae)

Climbing cutworms (Lepidoptera: Noctuidae) are serious pests of grapes in the southern interior of British Columbia. Abagrotis orbis is the most common of the 18 species collected from grapevines in the Okanagan Valley. Damage assessments suggested that the occurrence of winter annual mustards (Brassicaceae) in the vine rows decreased the number of buds damaged by climbing cutworms. To investigate these observations, thirteen plants from several families were tested for suitability as hosts for A. orbis, and choice test bioassays were used to test the relative attractiveness of herbaceous plants and post-dormant grape buds to A. orbis. Most of the tested plants were more attractive to A. orbis larvae than post-dormant grape buds, however 100% mortality of first and fifth instar larvae occurred when they were reared on shepherd’s purse, Capsella bursa-pastoris, leaves. Feeding on leaves of Bok Choy, Brassica rapa var. chinensis, and whitlow grass, Draba verna, resulted in mortality later in the larval stage.