Biological Control of Leafy Spurge: An Emerging Success Story

Abstract

Leafy spurge (Euphorbia esula L.) is a deep-rooted, perennial weed with erect stems 40 to 80 cm tall. The weed reproduces by both vegetative buds and the production of large quantities of seeds. A native of Eurasia, leafy spurge was first reported in the state of Massachusetts in 1827. Leafy spurge now occurs abundantly on the northern Great Plains of the United States and the prairie provinces of Canada, where it often forms stands dense enough to displace native plants and restrict cattle grazing. Biological control of leafy spurge in the United States began in the 1960s with the introduction of Hyles euphorbia. Fifteen nonindigenous insect species have been approved for release in the United States for the control of leafy spurge. Different biological control agents affect the leafy spurge plant in different ways. Primary methods of attack include consumption of above-ground plant material, consumption of root material, and blocking seed production. Aphthona sp. flea beetles have produced the greatest impact on leafy spurge. A. nigriscutis and A czwalinae/lacertosa impact the plant by ovipositing eggs at the base of the plant. The resulting larvae feed on leafy spurge roots, increasing plant morbidity, reducing plant