Monday, December 10, 2007
D0099

Impact of landscape heterogeneity on soybean aphid and natural enemy abundance in Jasper County, Iowa

Nick Schmidt, schmidni@iastate.edu1, Matthew E. O'Neal, oneal@iastate.edu1, and Lisa Schulte, lschulte@iastate.edu2. (1) Iowa State University, Entomology, 113 Insectary, Ames, IA, (2) Iowa State University, Natural Resource Ecology and Management, 142 Science II, Ames, IA

The soybean aphid Aphis glycines Matsumura (Hemiptera: Aphididae) is an invasive pest of soybean, Glycine max, in the United States. In the last five years research has shown that the predator community in U.S. soybean is capable of suppressing soybean aphid below economic levels. This community, comprised mostly of generalist predators has been shown to respond favorably to landscapes that have a greater amount of heterogeneity, that are not dominated by annual crop production. In Iowa, tallgrass prairie was the dominant habitat before ever-increasing intensification of agricultural practices began in the mid-1800s. Therefore, in the course of a 2-year project, we aim to determine how the soybean aphid and it’s natural predator community respond to a landscape that is comprised with varying amounts of tallgrass prairie. The study site was located at Jasper County, Iowa in and around the Neal Smith National Wildlife Refuge, the largest reconstructed tallgrass prairie in the U.S. (>5,000 acres planted). Soybean aphids and their predators were monitored in 32 soybean fields with visual-counts, yellow-sticky cards, and sweep-nets each week from June – September. During 2006 we observed populations of soybean aphids well below the economic threshold. Interestingly, in 2006, regression analysis revealed a positive response of soybean aphids to increases in landscape heterogeneity and no response in predator abundance. These results are from one of many distances yet to be analyzed.


Species 1: Hemiptera Aphididae Aphis glycines (soybean aphid)