Lepidopteran borers are the most devastating field pests of maize in West and Central Africa. In view of the rapidly changing climate which favours an upsurge of more destructive biotypes of insect pests, diverse sources of resistance from different genetic backgrounds need to be harnessed for crop improvement purposes. Forty tropical maize inbreds comprising adapted and exotic lines from International Institute of Tropical Agriculture (IITA) and International Maize and Wheat Improvement Centre (CIMMYT) maize breeding programs were evaluated for resistance to two species of stem borers- Sesamia calamistis and Eldana saccharina at Ibadan and Ikenne, Nigeria, under artificial infested and non-infested conditions in 2015 and 2016 cropping seasons. The experiment was laid out in a randomized complete block design in three replicates. Data were collected on agronomic traits and stem borer damage parameters. On average, the CML lines had relatively higher grain yield despite the high level of stem tunneling, stalk breakage and cob damage, with the exception of CML 67 (0.19 ton/ha) and CML 71 (0.06 tons/ha). BD 74-395 had the highest yield (1.45 t/ha) among the BDs, despite its high stalk breakage and cob damage. Among IITA lines, KU1414SR/SR, 1368 and 9030STR were the highest yielding with grain yields of 1.71, 1.39 and 1.19 t/ha, respectively. Moderate to high heritability was observed among the stem borer damage parameters. Negative genetic gain was observed in stem tunneling. Mean square of lines was significant for all the traits studied. The top-performing inbreds were similarly grouped using the rank summation index and principal component analysis. The exotic lines had good adaptability and showed potential as sources of stem borer resistance, and could therefore be explored in breeding programs for resistance to Eldana and Sesamia.
Key words: Eldana saccharina, maize inbreds, resistance, Sesamia calamistis, tropics.
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