Resistance to Chilo Partellus In CIMMYT Tropical Inbred Lines.

Lepdiopteran stem borers are major insect pests of maize in East Africa, estimated to cause losses of between 13-45% depending on the maize variety and stage of attack. Amongst the stem borers, Chilo partellus is the most economically damaging species in E. Africa. Knowledge of patterns of diversity in genetic resources is of importance in maize breeding in order to maximize heterosis in hybrid combinations and to maintain diversity of breeding lines. The objective of this study was to evaluate CIMMYT inbred lines for resistance to C. partellus using artificial infestation. One hundred twenty CIMMYT lines were evaluated twice at Kenya Agricultural Research Station-Kiboko for stem borer damage, in an Alpha lattice design with three replications. Each line was planted in two 5m rows at the spacing of 0.75m x0.25m. Ten plants in each plot were artificially infested with 5 borer neonates 3 weeks after planting. The remaining plants were concurrently treated with an insecticide to act as a control for comparison. Data were collected on stem borer exit holes and stem tunneling, which are used as indicators for levels of resistance. Data were analyzed using SAS package and means separated using least significance difference (LSD) at 5% level of significance. The lines differed in the level of stem borer damage. Based on number of stem borer exit holes (EH) and stem tunneling (ST), highest levels of resistance were recorded in SM-176-34, SM-176-44, SM-180-26, SM-176-61, and SM-176-13 with stem tunnel means of between 1.7 and 2.5 cm and exit hole means of between 0.7 and 1.5. The longest tunnel mean of 22.08 cm and largest number of borer exit holes of 9.4 were all recorded in SM-176-55. These resistant lines could be used for improvement of C. partellus resistace.