Combining Insects Pests Resistance Genes for Chilo Partellus and Sitophilus Zeamais in Maize Hybrids: Diallel Analysis.

The spotted stem borer, Chilo partellus, a major field pest of maize, and the storage pest, Sitophilus zeamais, are widely distributed in all major maize growing ecologies in Kenya. The two make a destructive yield loss force with estimated yield losses of 15% in the field and 17-40% in storage. Host plant resistance has been achieved for each of these pests in separate inbred lines and hybrids, however, no combined field and pot-harvest insects’ pests resistance studies have been studied in Kenya. A study was carried out to determine whether resistance to the two pests can be combined in hybrids using 12 parents diallel. The seedlings were screened for stem borer resistance by artificially infesting with 10 C. partellus neonates, and  at harvest, 100g of grain was infested with 45 unsexed adults of S. zeamais and P. truncates, for the post-harvest resistance Screening.

There were highly significant (≤ 0.001) mean square for yield, both under infestation and protected plots. The stem borers’ and postharvest insects’ resistance traits; leaf damage scores, exit holes, cumulative tunnel length, dust weight, live insects and weight loss; were also highly significant (≤ 0.001)  in six environments. Parents; 2, 3, 6, 7, and 10 contributed to higher Chilo partellus resistance genes in hybrids (≤ 2.3), while parents, 2,3,8,9,and 10 contributed had higher Sitophilus zeamais resistance genes. General Combining Ability effects for lead damage scores and undamaged kernels for Sitophilus zeamais were highly significant (≤ 0.001, 71-77%). Hybrids; 3X10, 3X9, 2X9, 5X8, and; showed combined resistance to both pests, with grain yield 6.0, 6.5, 7.4 and 8.2 t/ha respectively.  The parents can be used as sources of resistance genes in developing hybrids with combined resistance to field and storage pests in maize production.