Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

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.