Influence of Nitrogen on Population Parameters of Potato Insects: Abundance, Development, and Damage of the Colorado Potato Beetle, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae)

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Abstract
Population parameters of Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), were compared on potatoes fertilized with different levels of nitrogen (N) (0, 56, 84, 140, and 224 kg/ha). In general, abundance of CPB was similar for all treatments. Trends in the data showed that CPB larvae, adults, and egg masses were consistently more abundant (although not consistently statistically different) in the lowest and highest N treatments. The degree-days (°D 11.035.0 ) required for caged individuals to complete larval development were similar for all N treatments. Developmental rate of each population of CPB in each treatment was estimated by regressing the mean age of each population per sample date on accumulated °D 11.035.0 . Developmental rates were similar for most N treatments, but were negatively correlated with foliar concentrations of N. Estimates of partial defoliation by CPB were similar for all treatments. However, partial defoliation was greater (although not significant) in the lowest N treatment at the end of the growing season. Significance of these results concerning nutritional ecology of CPB and role of N in management of CPB is discussed.