Dynamical Role of Predators in Population Cycles of a Forest Insect: An Experimental Test
P. Turchin,
1*
A. D. Taylor,
2
J. D. Reeve
3
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.
1 Department of Ecology and Evolutionary Biology,
University of Connecticut, Storrs, CT 06269-3043, USA.
2 Department of Zoology, University of Hawaii, Honolulu, HI
96822, USA.
3 Southern Research Station, U.S. Department of
Agriculture (USDA) Forest Service, 2500 Shreveport Highway,
Pineville, LA 71360, USA.
*
To whom correspondence should be addressed. E-mail:
peter.turchin{at}uconn.edu
