Comparative resistance of improved maize genotypes and landraces to maize weevil

Abstract

A comparative study of maize (Zea mays L.) weevil (Sitophilus zeamais Motsch.) resistance in selected landraces and improved genotypes of maize, was conducted through a field experiment and laboratory assays. The maize grain characteristics that confer resistance to the maize weevil, Sitophilus zeamais Motschulsky, namely; grain hardness, weight and protein content, were compared in 50 improved maize genotypes developed by CIMMYT and two landraces (Cimambwe and Pandawe). The relative susceptibility of all maize experimental material to
the weevil, were also compared using Dobie’s susceptibility indices, grain weight loss and median development period. Genotypes were significantly different (p<0.05) for grain hardness but not for protein content. Genotypic differences in grain weight loss due to feeding by larval and adult S. zeamais were highly significant (P<0.001). The genotypes did not differ significantly (P>0.05) in the Dobie’s indices of susceptibility but exhibited a wide index range (0.77 to 9.11). The landrace, Chimambwe, had the second highest Median Development
Period, while Pandawe, had the heaviest kernels, though without noticeable advantage in resistance to the weevil. The Open Pollinated Varieties (OPVs) were not superior to hybrids according to the Dobie’s index of susceptibility. The possibility of developing maize hybrids or OPVs that are as resistant to the maize weevil, S. zeamais, as or even better than landraces is discussed and recommendations made.