Effects of Tree Density, Tree Species Diversity, and Percentage of Hardscape on Three Insect Pests of Honeylocust

Abstract

Honeylocust (Gleditsia triacanthos L. var. inermis) trees in urban areas are attacked principally by three insect pests: honeylocust plant bug, mimosa webworm, and honeylocust spider mite. One hundred honeylocust trees on the Purdue University campus were studied to better understand the influence of landscape characteristics on the populations of these insect pests. Specifically, the amount of hardscape, defined as imperviousness under and around trees, including roads, sidewalks, parking lots, and buildings; density of honeylocust; and diversity of tree species around each tree were calculated at numerous spatial scales and correlated with insect pest abundance on honeylocust. Each of these landscape factors influenced insect pest and their natural enemy populations on honeylocust trees at a wide range of scales. No single combination of these factors was associated with lower densities of honeylocust pests.