Abundance of Beneficial Arthropods on Woody Landscape Plants at Professionally-Managed Landscape Sites1

Eight 0.2–0.4 ha (0.5–1.0 A) sites managed by landscape professionals were monitored biweekly for beneficial arthropod activity. More than 30 generalist predator taxa were identified. Spiders and green lacewings were the most numerous taxa and both were found on all plant taxa sampled. Green lacewings, especially the egg stage, were the most numerous natural enemies detected on birch, crape myrtle, cherry, and oak trees accounting for 52.5, 49.9, 43.5, and 38.1%, respectively. Spiders accounted for 56.2% of the insectivorous arthropods observed on magnolia and were the most abundant predatory arthropod on azaleas comprising 46.5% of all arthropod predators/parasites across all properties. The most abundant predatory arthropods on junipers were spiders accounting for 75.5% of the beneficials encountered with ants (associated with an early season aphid outbreak), green lacewing larvae, lady beetles, harvestmen, and parasitic wasps comprising 15.8, 0.4, 4.3, 0.4, and 1.2%, respectively. Spiders were the most abundant predators on boxwood accounting for 70.6% of the natural enemies. Index words: integrated pest management, beneficial arthropods, green lacewing, spiders, urban landscape, ants. 1Received for publication November 2, 2000; in revised form January 28, 2002. 2Graduate Student. Current address: University of Maine Pest Management Office, 491 College Avenue, Orono, ME 04473. 3Professor and corresponding author. 4Professor and Extension Program Coordinator, Department of Entomology, University of Georgia, Athens, GA 30602. Significance to the Nursery Industry Natural enemies in managed landscapes were identified and quantified. Identification of these taxa is the first step in determining their impact in urban landscape pest reduction and incorporating them into decision-making guidelines for landscape professionals. This information can be used to adjust management practices to enhance insectivorous arthropod activity and potentially reduce pesticide inputs. Furthermore, the identification of plant materials that support greater abundance of natural enemies will provide the nursery industry and landscape managers with additional information increasing the marketability of these plants. The study also provides baseline data for further research in landscape pest management.