| Colorado potato beetle (Leptinotarsa decemlineata Say) is an important pest of potato and has developed resistance to many insecticides. With current and future restrictions on pesticides, ecologically safe alternatives for Colorado potato beetle management are needed. The goal of this project was to develop Heterorhabditis marelatus (Liu and Berry), an entomopathogenic nematode, as a biological control alternative for Colorado potato beetle through understanding its pathogenicity, adaptation to field edaphic factors, most effective rates, and the optimum time of application. Under controlled conditions, H. marelatus survival and pathogenicity was highest in sand and sandy loam soil with water moisture levels between −0.4 and −0.001 MPa. In field plots naturally infested with Colorado potato beetle, treatments of 333 million, 667 million or 1 billion H. marelatus /m2 of soil in 2000 and 2001 reduced beetle survival in contrast to control plots. Application timing (when 4th instar larvae were first present, peak of 4th instars or at peak pupation) did not significantly affect Colorado potato beetle survival but significantly more adults emerged in controls than in H. marelatus treated plots. Overall, the results suggest that H. marelatus has a potential for managing Colorado potato beetle under field conditions. |
