Species Composition of Cutworm (Lepidoptera: Noctuidae) Larvae in South Central Washington Vineyards

Abstract

Abstract The major grape (Vitis spp.)-growing areas of Washington were surveyed during 2003–2007 to determine the cutworm species present as larvae in vineyards during spring when grape buds and young shoots were vulnerable to cutworm (Lepidoptera: Noctuidae) damage. We sampled vineyard floors during daytime, vines at night because cutworms are active at night, and vines during the day. In total, 1,003 larvae were collected and 650 were reared to adults and identified. Twenty-five species were found: 22 on the ground, eight on vines at night, and two on vines during the day. Almost 75% of the cutworms on vines at night were Abagrotis orbis (Grote) and 19% were Agrotis vetusta Walker. The spotted cutworm, Xestia c-nigrum (L.), and the redbacked cutworm, Euxoa ochrogaster (Guenée), were reported previously to be the major cutworm pests of grapes in Washington, but only four X. c-nigrum and no E. ochrogaster were collected. Abagrotis orbis larvae were collected on grapes at night from mid-March to late April. Adults emerged in the laboratory in mid-May, and they were present during the summer. Agrotis vetusta larvae were collected on grapes from 1 to 30 April. This species had a long prepupal period during the summer, followed by a pupal stadium of ≈3 wk. Mean adult emergence was in early August. Both species were univoltine, with mating and egg laying during the fall followed by overwintering as small larvae.