Two studies were conducted to evaluate the relative attractiveness of floral habitats that may provide nectar and pollen food resources to natural enemies of agricultural insect pests in North Carolina. In the first study, timed observations were made of insect flower-feeding to estimate attraction of natural enemies to 16 plant species in 2004 and 5 plant species in 2005. Insects were identified to the family level and assigned to 1 of 6 feeding groups. In both years, crop predators fed from fennel (Foeniculum vulgare P. Mill.) flowers in greater abundance than from any other flowers observed. Crop parasitoids fed most often on fennel in 2005. In both years, the remaining insect feeding groups other than pollinators were not significantly affected by flower species. In 2005 the response of representatives of 3 families of egg parasitoids (Mymaridae, Scelionidae, and Trichogrammatidae) to 6 habitat plants (black-eyed Susan, buckwheat, fennel, cock's comb [Celosia cristata L.], Shasta daisy [Leucanthemum × superbum (J. W. Ingram) Berg, ex Kent.], and yarrow [Achillea millefolium L.]) was determined. Crabgrass (Digitaria spp. Haller), that exhibited no obvious flowering, served as a control. Results demonstrated that flower species and height affected insects of all 3 families of parasitoids, but removal of flowers only affected scelionids which were trapped in greater abundance in cock's comb plots at flower height. Mymarids were most abundant at 0.5 times the flower height in black-eyed Susan plots regardless of flower presence, and trichogrammatids were trapped in greatest abundance at 0.5 times the canopy height in unmowed crabgrass plots. Our results indicate that habitat plantings may attract egg parasitoids, but that flowers themselves do not appear to be responsible for this attraction.
3Department of Crop Science.