Spatial dynamics and impacts of Pissodes terminalis (Coleoptera: Curculionidae) in regenerating stands of lodgepole pine

Abstract

The spatial distribution of lodgepole pines attacked by Pissodes terminalis Hopping was analysed in spaced and unspaced plots located in the Interior Douglas-fir biogeoclimatic zone in south central British Columbia. The mean area potentially available (APA) described by Voronoi polygons around all attacked trees (7.2 ± 0.2 m 2) was significantly greater than the mean APA of unattacked trees (5.5 ± 0.2 m 2) in the spaced plot. The mean nearest neighbor distance of attacked trees also was significantly greater than that of unattacked trees in the spaced plot. In the unspaced plot, all trees in the plot (attacked and unattacked), and just attacked trees, approached a clumped distribution. In the spaced plot the attack pattern in any given year was clumped, but cumulatively, the trees attacked by P. terminalis approached a random distribution. The largest trees were most likely to be attacked and the most noticeable defect was a crook. Height loss due to weevil attack was 31.4% of the annual potential height increment in the year of attack, and 17% in the year following attack. Trees with ample growing areas are more likely to sustain severe damage due to weevil attacks. Delaying spacing until trees are > 15 years old is recommended to reduce the impact of weevil attack.