White Pine Weevil (Coleoptera: Curculionidae) Attack on White Spruce: Spatial and Temporal Patterns

The spatial attack pattern of white pine weevil, Pissodes strobi (Peck), on white spruce, Picea glauca (Moench) Voss, was studied in a 10-yr-old plantation in the interior of British Columbia. The spatial distribution of the weevil attack changed over time as the outbreak intensified. In the initial stages of the infestation, weevil attack distribution was aggregated, but changed to random when the infestation reached intermediate levels. When the infestation was at peak, attacks followed the pattern of host trees and the distribution was regular over the entire plantation. When attack was aggregated, weevils tended to attack neighboring trees, but not necessarily the 1st nearest neighboring tree. The probability of attack was dependent on the distance from the weevil source (i.e., distance to the trees attacked in the previous year) and on the resistance level of the tree. However, when the attack was at peak, every tree in the plantation was equally accessible to the weevils, and the distance to the attacked tree of the previous year played no role in determining the attack probability and attack was solely dependent on tree resistance level. It is expected that this study will be helpful in formulating a spatially explicit model of white pine weevil attack in British Columbia.