Amanda M. Koss and William E. Snyder
Department of Entomology, Washington State University Pullman WA 99164-6382, USA
We are currently studying the biological control of two major pests of potato in Washington state, the Colorado potato beetle (Leptinotarsa decemlineata) and the green peach aphid (Myzus persicae). We characterized the natural enemy communities from production potato fields in eastern and central Washington that varied in their pest management regimes. We collected natural enemies from 6 fields treated with broad-spectrum pesticides, 6 fields treated with more selective pesticides, and 3 organic fields. The community of potato beetle and aphid natural enemies was comprised primarily of generalist predators, including Nabis and Geocoris bugs, carabid beetles, and spiders. Natural enemies were most abundant in the organic and soft chemical fields, and less common in the broad-spectrum fields. In a field experiment we manipulated predator densities to better understand the impact of the generalist predator guild on potato pests. The predators were very effective at controlling M. persicae, reducing aphid densities by 90%, but had a weaker impact on L. decemlineata.
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA