Color, odor, and species preferences of Copidosoma bakeri to prospective cover crops to enhance control of cutworms

Cutworms (Lepidoptera: Noctuidae) are economically important pests of multiple field crops, but are difficult to control with insecticides. Biological control with native parasitoids may offer a sustainable alternative for pest management. Cover crops improve the availability of resources required by parasitoids to increase their effectiveness as biocontrol agents. Copidosoma spp. (Hymenoptera: Encyrtidae) have the potential to control several species of cutworms in the Canadian Prairies. However, their foraging preferences for non‐host food items are unknown. In this study, we tested flower color and odor preferences of Copidosoma bakeri (Howard) across nine potential cover crop species and investigated how these resources affect survival and longevity of the female wasps. Results indicated that the wasps were most attracted to plants with yellow flowers in the family Brassicaceae (i.e., camelina, mustard, and canola). In multiple‐choice tests, the wasps preferred camelina over all other flower species, and showed an intermediate preference for mustard and canola. In dual‐choice tests with color paper, the wasps preferred yellow over white, and the light yellow of camelina over the bright yellow of canola and mustard, whereas they showed a preference for the odors of mustard and canola. Life expectancy was increased when the wasps were provided floral resources compared to the absence of a food source. Later planting dates and mixed‐species plantings of cover crops resulted in flowering times that better coincided with native wasp emergence. Camelina is known to suppress weeds and may be used as a habitat management tool for enhancing parasitism of cutworms by C. bakeri in the Canadian Prairies. However, further testing is needed to achieve late flowering well into August and early September and to ensure planting additional Brassica spp. does not attract more late‐season pests to cash crops such as canola.