Evaluation of quality protein maize inbred lines for resistance to maize weevil Sitophilus zeamais (Coleoptera: curculionidae) and other important agronomic traits

Abstract

Searching new sources of resistance to the maize weevil are critical in a successful breeding program to address grain damage by postharvest pests. This study was undertaken to evaluate resistance in 28 quality protein maize (QPM) inbred lines against Sitophilus zeamais infestation and their important agronomic attributes, and consequently their value for use in breeding programs to develop resistant QPM hybrids. Susceptibility index (SI), which considers the progeny number in the F1 generation and the time the insects take to mature from egg to adult, was used to measure the susceptibility. Out of the 28 inbred lines tested, one inbred line (CML-142) was resistant, three (CML-144/144-7-b (F2)-4-2-1-1-1-1-1, POOL 15QPFS-693-B-2-B-#-B-B-B-# and CML-149) were moderately resistant and the remaining 24 inbred lines were categorized as susceptible to highly susceptible. Importantly, those inbred lines that are resistant and moderately resistant had better yield and other agronomic performances as compared to the susceptible ones. These resistant and moderately resistant inbred lines showed considerable reduction in grain damage and losses for S. zeamais, suggesting that they contained genes that confer resistance to the pest. Correlations between kernel size, breadth and texture with some important susceptibility parameters were found to be significant, indicating possible influence of these factors together with others in determining the susceptibility of the QPM inbred lines to S. zeamais. Identification of QPM lines resistant to S. zeamais in the present study offers an opportunity to breed for resistance to maize weevil in developing QPM hybrid with enhanced resistance to S. zeamais.