Survival of three commercially available natural enemies exposed to Michigan wildflowers

Flowering plants are often used in habitat management programs to conserve the arthropod natural enemies of insect pests. In this study, nine species of flowering plants representing six families commonly found in North America east of the Rocky Mountains were evaluated based on how much they extended the lifespans of three commercially available natural enemy species in cages with cut flower stems compared with cages containing water only. The natural enemies used in the experiments were a lady beetle (Coleoptera: Coccinellidae: Hippodamia convergens Guérin-Méneville), a predatory bug (Heteroptera: Anthocoridae: Orius insidiosus (Say)), and an aphid parasitoid (Hymenoptera: Braconidae: Aphidius colemani Viereck). The plant species that most extended the lifespans of all three natural enemies were Monarda fistulosa L. (Lamiaceae), Solidago juncea Aiton (Asteraceae), and Daucus carota L. (Apiaceae). Agastache nepetoides (L.) Kuntze (Lamiaceae), Lobelia siphilitica L. (Campanulaceae), and Trifolium pratense L. (Fabaceae) were intermediate in their support of natural enemies. One plant species, Penstemon hirsutus (L.) Willdenow (Scrophulariaceae), did not contribute to the longevity of natural enemies any more than water alone. These results emphasize the need for multi-species evaluations of flowering plants for conservation biocontrol programs, and the variability in plant value for natural enemies.