Restance in maize genotypes to the spotted stem borer, Chilo pm-tellus (Swinhoe) (Lepidoptera: Crambldae)

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Addis Ababa University


In the current study, 134 maize genotypes were screened against C. partelhls at Melkasa Agricultural Research Center (MARC) under field and laboratory conditions. Initially, 134 maize lines against Chilo partelhls were screened based on the number of leaf infestation and dead heart. From 134 lines tested in the field, 34 lines (.'010% infestation) showed promising in terms of C. partelhls resistance, 74 (11-25% infestation) lines were intermediate and the rest 20 lines (>25% infestation) were susceptible. From each category four lines were randomly selected and planted in tlu'ee replication using completely randomized design (CRD) to verify the plantsresult obtained under field screening. Number of egg masses and leaf infestation per plant were recorded and then dissected to check for number of borer density, larvae exist holes and tunnel length. There were significant differences for all parameters were observed among the three categories. Furthered more, the results confirmed the presence of similar trends with field screening result in leaf infestation with screen house outcome. Finally, the growth and development of the borer were measured on the most susceptible and resistant maize lines which were de!ermined under natural, and m1ificial infestations. These maizelines were examined for their relative resistance to the C. parfel!us (Swinhoe) in relation to feeding. Freshly hatched larvae of C. parfel!/ls were allowed to grow on the leaf sheath and stem cuts of the two lines separately. The rate of growth, egg lying, egg hatchability, pupation, and adult emergence were studied. The insects showed better growth when reared on susceptible maize line than on the resistant line. The majority of Ethiopian farmers have small land holdings. For these reasons, and the hazards associated with insecticide applications, there is a great need to develop varieties that can resist pest attack with out requiring any traditional expenditure by the farmers.