Dynamical role of predators in population cycles of a forest insect: an experimental test.

Abstract

Population cycles occur frequently in forest insects.Time-series analysis of fluctuations in one such insect, the southern pine beetle (Dendroctonus frontalis), suggests that beetle dynamics are dominated by an ecological process acting in a delayed density-dependent manner.The hypothesis that delayed density-dependence in this insect results from its interaction with predators was tested with a long-term predator-exclusion experiment. Predator-imposed mortality was negligible during the increase phase, grew during the year of peak population, and reached a maximum during the period of population decline.The delayed nature of the impact of predation suggests that predation is an important process that contributes significantly to southern pine beetle oscillations.

Citation

Turchin, P.; Taylor, A.D.; Reeve, J.D. 1999. Dynamical role of predators in population cycles of a forest insect: an experimental test. Science 285: 1068-1071