© 1986 Heron Publishing—Victoria, Canada
Douglas-fir and western larch: chemical and physical properties in relation to Douglas-fir bark beetle attack
A. N. Reed (1), J. W. Hanover (2) and M. M. Furniss (3)
1. USDA, ARS, Tree Fruit Research Laboratory, Wenatchee, Washington 98801, USA / 2. Department of Forestry, Michigan State University, East Lansing, Michigan 48824, USA / 3. USDA Forest Service, Moscow, Idaho 83843, USA / Received September 12, 1986
Summary
Frequency of Douglas-fir bark beetle, Dendroctonus pseudotsugae Hopkins (Coleoptera: Scolytidae), attack on western larch (Lark occidentalis Nutt.) was negatively correlated with 3-carene content of the xylem oleoresin. Concentrations of all oleoresin volatiles
from stem cores of standing trees were higher in Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) than in western larch with the single exception of 3-carene. Successful brood production by the Douglas-fir
bark beetle in standing trees of Douglas-fir but not western larch may therefore be explained, at least in part, by the high
3-carene content of western larch. Other differences between the species that might affect susceptibility to beetle attack
include thinner phloem, higher phloem moisture content and larger diameter vertical resin ducts in western larch compared
with Douglas-fir. Live standing western larch had no oleoresin exudation pressure, suggesting that this trait is not associated
with resistance to attack by the Douglas-fir bark beetle in this species.
