Genetic variability in exotic × adapted maize (Zea mays L.) germplasm for resistance to maize weevil.
Infestation of maize (Zea mays) kernels by maize weevil (Sitophilus zeamais) is a serious problem in the tropical and subtropical areas. Genetic variability for resistance to maize weevil in domestic US maize germplasm has previously been identified. However, the newly developed germplasm from the US Germplasm Enhancement of Maize project to broaden the genetic base of maize in the USA has not been evaluated for resistance to maize weevil. Sixty-one exotic × adapted maize breeding crosses were evaluated for remaining kernel weights (RKW) (100 g minus loss) after feeding by maize weevils in 1995 and 1996. Highly significant genotypic effects for RKW in both years indicated that a substantial genetic variability for resistance to maize weevil existed among the maize breeding crosses. The 2-year data revealed the presence of true genetic variability among the breeding crosses for maize weevil resistance (genetic variance component (σ2g) = 12.34), which should prove useful to develop maize weevil resistant hybrids or varieties. Broad-sense heritability (h2b) on a plot basis for RKW was 0.27 in 1995 and 0.30 in 1996, suggesting relatively stable genetic variability for this trait across years. The h2b for RKW from the pooled data was 0.21, which implied that progress from selection would be slow. Genotype environment interaction for RKW was not detected; however, the effect of years was relatively large. Identification of genetic variability for maize weevil resistance within an environment is possible.