Experimental study of the efficiency of a reduced index in Tribolium

The relative efficiency of a reduced index (IR) relative to a full index (IF) was compared in an experiment with Tribolium. The selection objective included pupal length, adult weight, and egg mass. The reduced index was based on pupal length and adult weight, whereas the full index was based on these traits and also on egg mass. There were five generations of selection with four replicates, and a selected proportion of 20%. For each replicate, an unselected control was produced. Responses were significant in the IF and IR lines. Responses for the selection objective differed significantly between lines (p<0.01). The efficiency of the IR line relative to the IF line was 0.52, similar to the expected efficiency of 0.51. The IF and IR lines did not differ significantly for pupal length nor adult weight, whereas the response for egg mass in the IF line was significantly different from the response in the IR line. Realized heritability was greater in the IF line (0.63 +/-0.05) than in the IR line (0.37 +/-0.16). The deleted trait (egg mass) has high heritability and genetic and phenotypic correlations nearly equal to zero with the other two traits included in the selection criterion. The results show the importance of including index traits with high genetic value that are independent of other traits, and they could be useful in breeding programs simultaneously considering production and reproduction traits with nearly zero correlations between them.