Ayres Abstracts

Friedenberg, N.A, B.M. Whited, D.H. Slone, S.J. Martinson, and M.P. Ayres.  2007. The differential impact of a destructive forest pest on two species of Pinus.  Canadian Journal of Forest Research 37: 1427-1437.   link to full article   pdf

Abstract.  Patterns of host use by generalist herbivore pests can have serious consequences for natural and managed ecosystems, but are often poorly understood. Here, we provide the first quantification of large differential impacts of the southern pine beetle, Dendroctonus frontalis Zimmermann, on loblolly pine, Pinus taeda , and longleaf pine, P. palustris , and evaluate putative mechanisms for the disparity. Spatially extensive survey data from recent epidemics indicate that, per km2, stands of loblolly vs. longleaf pine in four forests (380-1273 km2) sustained 3-18 times more local infestations and 3-116 times more tree mortality. Differences were not attributable to size or age structure of pine stands. Using pheromone-baited traps, we found no differences in the abundance of dispersing D. frontalis or its predator, Thanasimus dubius Fabricius, between loblolly and longleaf stands. Trapping triggered numerous attacks on trees, but the pine species did not differ in the probability of attack initiation, nor in the surface area of bark attacked by growing aggregations. We found no evidence for post-aggregation mechanisms of discrimination or differential success on the two hosts, suggesting that early colonizers discriminate between host species before a pheromone plume is present.

Keywords: bark beetle, forest pest, herbivory, host range, specialist, secondary attraction


Return to Publications