| Abstract: | Previous attempts to shift the (Z)-11-/(E)-11-tetradecenyl acetate ratio of pheromone components in the redbanded leafroller moth (RBLR), Argyrotaenia velutinana, by several selection protocols showed that this ratio is strongly canalized. Analysis of the complete seven-component blend, however, showed that a Geneva laboratory stock of RBLR had a lower percent (20%) of the E9–12:OAc minor component compared to the E11–14:OAc component than a population of RBLR from North Carolina (31%). Hybrid populations from these two cultures were used in a two-way family truncation selection scheme in which families were selected for either the lowest (low line) or the highest (high line) ratio of E9–12:OAc/E11–14:OAc. After three generations of selection, the low line had 14% E9–12:OAc relative to E11–14:OAc and the high line had 42%. The selection pressure was removed in generations 4–9, and the low line remained unchanged at 14% E9–12:OAc; but in the high line, it drifted to 53%. Studies were conducted to estimate heritability and realized heritability. The realized heritability calculated for each generation of selection averaged 1.14 for the low line and 1.50 for the high line. These calculations, along with estimated heritability values of 0.416 and 0.644 for reciprocal crosses, indicate some plasticity in the E9–12:OAc/E11–14:OAc ratio. This ratio was positively correlated to the total amount of 12-carbon components to 14-carbon components, but was negatively correlated to the Z/E ratio of Δ11-tetradecenylacetates. The results of two studies on the canalization of various components of the RBLR sex pheromone blend indicate that there is limited potential in this insect for manipulation of the blend ratios in the laboratory. |
