PARENT SESSION
Poster Session #4: Herbivory.
Monday, August 5. Presentation from 5:00 PM to 6:30 PM. Exhibit Hall B & C, TCC
47
Scale-dependence of host susceptibility to southern pine beetle.
Ylioja, Tiina*,1, Slone, Daniel2, Veysey, Jessica1, Ayres, Matthew1, 1 Dartmouth College, Hanover, NH2 USDA Forest Service, Pineville, LA
ABSTRACT- Ecological patterns can vary when different processes dominate on fine vs. coarse spatial scales. Southern pine beetle, Dendroctonus frontalis, attacks >10 pine species in southeastern United States. Two commonly used host species, loblolly and Virginia pine, co-occur as mixed stands or as a mosaic of single-species stands within the forest landscape. We compared the susceptibility of these two pines to bark beetles and tested whether susceptibility was a consistent species attribute or whether it was influenced by the landscape configuration of two host species. When pine species were intermixed (at ca. 10x10 m), flying beetles preferentially attacked Virginia pine, so mortality within infested stands was only 0-66% in loblolly pine vs. 65-100% in Virginia pine. However, beetles had lower reproductive success in Virginia pine than in loblolly pine (0.6 vs. 4.1 adult progeny/attacking adult). Consequently, patterns differed at the landscape scale (ca. 1000 km2) where beetle demography, rather than behavior, was the prevailing driver. Loblolly stands (of 1-100 ha) were twice as likely to be infested as comparable Virginia stands, and stands that were infested lost more area to beetles. The relative susceptibility of pine species to bark beetles can change with the spatial scale of observation.
KEY WORDS: spatial scale, Dendroctonus, Pinus, host-resistance