Evaluating risk of Colorado potato beetle (Coleoptera: Chrysomelidae) infestation as a function of migratory distance

Experiments were conducted during a 4-yr period between 1991 and 1994 to quantify tile relationship between field isolation (defined as the distance between a potato planting and the location of all potato fields grown the previous season) and Colorado potato beetle, Leptinotarsa decemlineata (Say), initial immigration density. Our objectives were to determine how far beetles could disperse to colonize new host fields and to develop a method for deter mining infestation risk associated with potential new potato planting sites. In total, 22 fields were monitored during the 4-yr period for beetle infestation. The location of these fields and all fields grown across tile floor of an agricultural valley the previous season were recorded. These data were used to model the effects of distance on beetle dispersion and colonization. Large differences in infestation pressure existed among fields and years. These differences were well explained by summing the influence of all previous potato locations using a linear decrease with distance and a maximum dispersal distance of 1,449 m. This model was used to generate a risk map to evaluate potential potato growing areas.