Studies on the Effect of Intercropping and Application of Livestock Manure on the Infestation and Damage of Kale (Brassica Oleracea L. Var Acephala) By Diamondback Moth, Plutella Xylostella (Lepidoptera: Plutelliddae) in A Bio-Farming Systems.
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Date
2007-05
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Addis Ababa University
Abstract
Kale (Brassica oleracea var. acephala) is an important source of income to many small-scale
farmers in Ethiopia and is a major dietary component for many Ethiopians. The production of kale
is, however, constrained by several pests among which diamondback moth (Plutella xylostella) is
the major insect pest. Control of diamondback moth has mainly been by pesticides, which has
resulted in pest resistance and pollution of the environment. This study attempts to look into
alternative environmentally friendly ways of controlling diamondback moth larvae on kale in
selected site in Ethiopia.
Field studies and Screen house experiments were conducted to determine the effect of
intercropping and livestock manure on the diamondback moth larval density and damage on kale.
Parasitoid species and percentage parasitism are also determined. Intercropping kale and onion
(Allium cepa) both with and without manure significantly reduced (P<0.05) the densities of P.
xylostella larvae and damage on kale leaves compared to control plots. The lowest larval densities
and damage on leaves were recorded in kale- onion intercropping with manure application. In
addition significant reduction (P<0.05) in leaf damage was observed in Screen house experiments
of kale grown on manure applied soil. Moreover, significantly higher marketable leaf weights were
recoded in kale monocrop with the application of livestock manure as compared to kale monocrop
without manure application.
Oomyzus sokolowskii (Kurdjumov) (Hymenoptera: Eulophidae) which is larval-pupal parasitoid
and Apanteles spp. (Hymenoptera: Braconidae) which is larval parasitoid were recorded on
diamondback moth during the study. Parasitism in diamondback moth larvae and pupae by these
parasitoids were 16.33%. with O. sokolowski 9.96% and Apanteles spp. 6.37%. The results in the
present study indicate that intercropping kale with onions can be effectively used to suppress
diamondback moth larval density, reduce leaf damage and improve yield of kales.
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Biology