The influence of fallen tree timing on spruce beetle brood production

Publication Type:Journal Article
:2007
Authors:E. G. Hebertson, Jenkins M. J.
Journal:Western North American Naturalist
Volume:67
Pagination:452-460
Date Published:July
:1527-0904
:Dendroctonus rufipennis
:

This study compared brood production of the spruce beetle (Dendroctonus rufipennis Kirby (Coleoptera: Curculionidae. Scolytinae)) in downed host material felled during summer and spring seasons on the Wasatch Plateau in south central Utah. Thirty-three matched pairs of Engelmann spruce (Picea engelmannii Parry ex Engelm.) trees were selected for study in spring 1996. One tree of each pair was cut during August 1996 (summer-felled) and the other tree was cut in early April 1997 (spring-felled), so that trees would be colonized by spruce beetles of the same flight period. Brood adults were collected and counted from bark samples, which were removed from the top, bottom. and sides of all sample trees in October 1998. The number of emergent adults produced in June 1999 was determined from exit holes counted in bark samples removed form these same locations. Mixed-model procedures were used to compare differences in the mean number of adults produced in summer-felled verus spring-felled trees in each year. The results indicated that significantly fewer spruce beetles were produced in summer-felled trees than in spring-felled trees. More brood adults were also present in, or emerged form, unexposed hole aspects (bottom, north, and east) of sample trees than exposed aspects (top, south and west). These finding suggest that disturbances providing spruce beetles with an abundance of fresh host material in the spring result in the greatest potential for spruce beetle production, particularly beneath unexposed bark aspects. Examples of such disturbances include snow avalanches, blowdown, and snow and ice damage.

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith