Restance in maize genotypes to the spotted stem borer, Chilo pm-tellus (Swinhoe) (Lepidoptera: Crambldae)
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Date
2006-07
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Addis Ababa University
Abstract
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.
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Biology