Abstract
Resistance to galling adelgids varies among families of Engelmann spruce (Picea engelmannii P.).
Abstract
The Cooley gall adelgids (Adelges cooleyi) and the round gall adelgids (Adelges abietis - possibly with Adelges lariciatus, which gives rise to superficially similar galls) differentially [naturally] infested 110 half-sib families of Engelmann spruce (Picea engelmannii, about 15 yr old) in a genetic trial at 9 study sites in British Columbia (Canada). There was a negative genetic correlation (-0.53) between the infestations by the 2 gall-forming species. Cooley gall abundance exhibited a negative genetic correlation (-0.66) with tree growth, whereas round gall abundance exhibited a positive genetic correlation (0.79) with growth. Heritability (h2) of resistance against the adelgids averaged about 0.60 for Cooley gall adelgids and 0.20 for round gall adelgids.
