Common Buckthorn: A Keystone Invader in the Landscape

Project Investigators: Jacob Wenger, Chelsea Smith, Mary Gardiner, Andrew Michel, Douglas Landis, Matthew O'Neal and David Lusch.

Widespread occurrence of the exotic invasive shrub common buckthorn, Rhamnus cathartica, has resulted in cascading negative impacts across the north central U.S. A landscape approach to understanding and managing these effects is required to enhance agricultural production and protect the natural resource base. Common buckthorn invades natural area where it directly reduces native biodiversity. In addition, it serves as the primary overwintering host of the exotic soybean aphid, Aphis glycines, allowing it to successfully overwinter in the north central U.S. Soybean aphid negatively impacts the production of soybean and vegetable crops by direct feeding and vectoring plant viruses. Moreover, the presence of soybean aphid has facilitated an increase in the exotic multi-colored Asian lady beetle, Harmonia axyridis, leading to the decline of several native lady beetle species. Harmonia adults also invade homes where they cause human allergies. The goal of this regional project is to develop a fundamental quantitative understanding of the cascading impacts of this keystone invader on ecosystem function and services, and to develop economically and ecologically rational strategies for its management at landscape-scales. To accomplish this we are investigating how the level of buckthorn infestation in the landscape influences soybean aphid immigration into soybean fields, secondary dispersal of soybean aphid between soybean fields, soybean aphid-vectored virus infection in vegetable crops and H. axyridis reproductive success. In addition, by linking grower-oriented Extension and natural areas stewardship outreach we are working to create a network of informed volunteers prepared to synergize new partnerships and approaches to buckthorn management at landscape-scales.