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 distr ibution of the weevil attack changed over time as the outbreak intensi fied. In the initial stages of the infestation, weevil attack distribu tion was aggregated, but changed ro random when the infestation reache d intermediate levels. When the infestation was at peak, attacks follo wed the pattern of host trees and the distribution was regular over th e entire plantation. When attack was aggregated, weevils tended to att ack neighboring trees, but not necessarily the Ist nearest neighboring tree. The probability of attack was dependent on the distance from th e weevil source (i.e., distance to the trees attacked in the precious year) and on the resistance level of the tree. However, when the attac k was at peak, every tree in the plantation was equally accessible to the weevils, and die distance to the attacked tree of the precious yea r played no role in determining the attack probability and attack was solely dependent on tree resistance level. It is expected that this st udy will be helpful in formulating a spatially explicit model of white Dine weevil attack in British Columbia.