Multicolored Asian lady beetle (Coleoptera: Coccinellidae) activity and wine grape phenology: Implications for pest management

We determined the phenology of the multicolored Asian lady beetle, Harmonia axyridis (Pallas), adults in relation to the phenology of wine grapes (Frontenac and Marechal Foch) in Minnesota and Wisconsin vineyards to establish a management window for H. axyridis infestations in wine grapes. In addition, we also assessed the flight activity of H. axyridis in an agricultural landscape. The phenology of berry development and ripening was determined by recording berry size and sugar content of randomly selected berries. The phenology of H. axyridis was determined by tracking its flight activity with yellow sticky cards in vineyards and with a blacklight trap in an agricultural landscape. Berry development and ripening showed three distinct growth periods or phases. The end of growth period I averaged 9 July (Frontenac) and 11 July (Marechal Foch). Veraison, which marks the end of growth period II, averaged 25 July (Frontenac) and 3 August (Marechal Foch). Harvest, the third growth period averaged 18 September for Frontenac and 17 September for Marechal Foch. A major peak of H. axyridis captures occurred between veraison and harvest (i.e., the grape susceptible stage). A similar peak in the summer was observed in the agricultural landscape ≈10d before the major peak in the vineyards.