Resistance of white spruce to white pine weevil: Development of a resistance index

An index of resistance in white spruce, Picea glauca (Moench) Voss, to attack by the white pine weevil (Pissodes strobi Peck) was developed based on tree variables which measured attack intensity, severity and the tolerance of the tree to attack. The index, derived using principal component analysis, was used to screen 139 white spruce families from the interior of British Columbia in a replicated family trial, for resistance to weevil attack. The resistant ranking of the families was significantly related to the habitat characteristics of the parent trees as measured by elevation, longitude, latitude and by the ecological variables of biogeoclimatic zone, subzone and variant. Geographic sources of white spruce genotypes resistant to weevil attack were identified. These were mainly in the moist-warm habitats of the SubBoreal Spruce biogeoclimatic zone.