Genetic parameters and selection efficiencies in resistance to western gall rust, stalactiform blister rust, needle cast, and sequoia pitch moth in lodgepole pine

Genetic variances, heritabilities, and between-trait genetic correlations in resistance to western gall rust (Endocronartium harknessii), stalactiform blister rust (Cronartium coleosporioides), needle cast (Lophodermella concolor), and sequoia pitch moth (Synanthedon sequoiae) (Lepidoptera: Sesiidae) were investigated in a 21-yr-old lodgepole pine (Pinus contorta spp. latifolia) provenance-family trial with 778 wind-pollinated families in interior British Columbia. Selection efficiencies in expected improvement in resistance were compared among mass, family, sequential family-and-within-family, and combined family/individual index selection. Efficiencies in multitrait selection for overall resistance to the four pests based on different selection indices were also compared. Individual heritability for incidence of western gall rust was 0.50, stalactiform blister rust 0.32, needle cast 0.30, and sequoia pitch moth 0.21. Family mean heritabilities ranged from 0.39 to 0.65, The genetic correlation between incidence of sequoia pitch moth and stalactiform blister rust was 0.89, and between pitch moth and western gall rust 0.25. The genetic gain estimates from mass selection for resistance to the four pests varied from 14 to 31% at a 13% selection rate, On average, combined family/individual index selection was 5% more efficient than mass selection, and family and sequential family-and-within-family selection was about 38% and 16% less efficient than mass selection, respectively, Substantial improvement can also be expected from provenance selection, Multitrait index selection for overall resistance excluding sequoia pitch moth data was nearly as efficient as the full index. Indirect selection for resistance to sequoia pitch moth based on resistance for stalactiform blister rust was more efficient than direct selection. Selection for resistance showed little adverse effect on growth.