RECURRENT SELECTION FOR RESISTANCE TO LEAF FEEDING BY FALL ARMYWORM ON MAIZE

Populations and inbreds of maize, Zea mays L., with effective levels of resistance to damage by fall armyworm, Spodoptera frugiperda (J.E. Smith), are needed to transfer resistance to commercial hybrids for the U.S. Southeast. Recurrent S1 selection for resistance to leaf feeding by larvae of fall armyworm was conducted with an exotic maize synthetic, FAW-CC. Our objectives were to estimate genetic variances, heritabilities, and genetic gain and to evaluate effectiveness of selection by comparing predicted and realized progress after five cycles of selection. Variance components and heritabilities were estimated from the S1 progeny performance tests for each cycle of selection, and progress was determined from a replicated evaluation of populations per se that were generated by recombinations from each selection cycle. Estimates of genetic variance for resistance to leaf feeding, evaluated on a rating scale of 0 to 9 (0 = no damage, 9 = all leaves destroyed), were significant for all but the S1 progenies in the C1 generation. Significant genotype x location interactions also occurred among S1 progenies. Heritability estimates were significant (range = 0.45-0.77) for all but the C1 cycle S1s, and selection gains were about two-thirds as large as predicted from estimated parameters. The regression of leaf-damage rating on selection cycles gave a significant b value of - 0.31 units per cycle of selection. Advanced cycles of FAW-CC should be good sources of inbreds with intermediate to high levels of resistance to leaf feeding by larvae of the fall armyworm.