EXPERIMENTAL COMPARISON BETWEEN WEIGHT-FREE AND NONLINEAR INDEXES IN TRIBOLIUM

Effectiveness of weight-free and non-linear index selection to change pupal weight and pupal length was tested in Tribolium castaneum. The s election goal was (x1-K2) (x2-k2), where k1 and K2 are the smallest va lues for pupal weight (x1) and pupal length (x2), respectively. Two li nes were selected for four generations as follows: NL, non-linear inde x in which the selection criterion was (m1+G1-k1)(m2+G2-k2), where m1 and m2 are the population means for pupal weight and pupal length, and G1 and G2 are the selection indices for each breeding value based on information from both traits; WF, weight-free index selected for (x1-k 1)(x2-k2) directly. Three replicates per line was used and the proport ion of selection was 20%. The response observed in the WF line for the selection goal (19.40+1.01) was not significantly different from the response obtained in the NL line (21.07+1.84). Realized correlated res ponses in both component traits did not differ significantly. Rates of response were significant for the product value and pupal length (p < 0.01), and for pupal weight (p < 0.05). Realized efficiencies agreed closely with expectations. The superiority of the weight-free-index me thod over the classical independent culling levels can be determined f rom this study.