Evaluation of maize genotypes for resistance to Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae) infestation

The use of Sitophilus zeamais resistant maize germplasm for breeding new varieties can contribute to reduce hazardous insecticide use on stored maize. This study evaluated six maize genotypes, five genebank accessions (GH2354, GH3239, GH3324, GH3609, GH6182) and one commercial variety (OBAATANPA) for resistance to S. zeamais infestation. Maize grains were infested with adult weevils and data on number of grains with weevil damage, percentage weight loss, median developmental time and index of susceptibility was collected. Differences in the number of days to first adult emergence between genotypes were not significant (P > 0.05). Differences between genotypes for all other parameters evaluated were however significant (P < 0.05). Accession GH3609 recorded the most damaged grains (23.32%) and the highest (15.41%) grain weight loss, whereas OBAATANPA recorded the lowest (9.81%) damaged grains whilst the lowest weight loss (8.26%) was observed in GH6182. The proportion of damaged grains correlated with weight loss (r = 0.96) and index of susceptibility (r = 0.82). All evaluated genotypes were susceptible to S. zeamais attack. Little research has been conducted to identify S. zeamais resistant maize germplasm in Ghana. The results of this study should serve as baseline information in the screening for resistance to S. zeamais.