Introduction
The emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), poses a serious threat to all ash trees in North America. The larvae feed on phloem, producing galleries that eventually kill large trees in 3 to 4 years and small trees in as little as 1 year (Poland and McCullough 2006). A native of Northeastern China, Korea, Japan, Mongolia, Taiwan, and Eastern Russia, the species was first identified in the United States near Detroit, MI, in July 2002 (Haack 2006). The borer was probably imported into Michigan in the early 1990s via infested ash crating or pallets (Herms and others 2004).
The impact of EAB may be enormous. An estimated 8 billion ash trees exist in the United States, comprising roughly 7.5 percent of the volume of hardwood sawtimber, 14 percent of the urban leaf area (as estimated across eight United States cities), and with a value exceeding $300 billion (Poland and McCullough 2006).
Research into the spatial distribution of the host ash species helps us better understand the resource at risk and the potential for EAB spread. The USDA Forest Service’s Forest Inventory and Analysis (FIA) units continually conduct inventories across more than 100,000 plots in the Eastern United States (Miles and others 2001). This invaluable data source provides the information critical to the assessment of the ash resource, including the work reported here. For a detailed look, we rely on 30-m Landsat data that have been classified into forest types with associated ground samples to calculate ash content.
There are a variety of approaches for using computer models to predict the risk and spread of invasive insects, (e.g., Rykiel and others 1988, Sharov and Liebhold 1998, Sharov and others 1997, Sturtevant and others 2004, Turchin 2003). To summarize, modeling insect movement is a complicated venture, especially in heterogeneous landscapes. BenDor and Metcalf (2006) and BenDor and others (in press) have initiated a dynamic modeling approach to learn more about EAB spread and possible mechanisms to retard it. These authors also call for high resolution data on the ash resource and human-assisted components such as campgrounds to move this work forward. In this study review, we present a slightly different approach using higher resolution data bases.
The objectives of this work are to: (1) evaluate the ash quantity across the Eastern United States at a coarse level and in Ohio at a fine scale; (2) assess EAB spread and rate of spread through the region so far; and (3) begin to model future spread through the two modeling approaches of insects flying and insects riding with humans.
Encyclopedia ID: p3374
