The Relative Importance of Three Cabbage Aphid Species (Brevlcqryne Brassicae, Upaphis Erysimi ; Myzus Perslcae) and their Parasitoid Complex in Kenya
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Date
2000-05
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Addis Ababa Universty
Abstract
Studies on the relative importance of the three known species of cabbage
aphids (8revicory/le brass;cae (Unneaus), Myzus persicae (Sulz) and Upaphis
arysim/ (Kaltenbach» and their parasitoid complex in Kenya were carried out.
The studies involved farmers' rlelds' surveys and intet"llews and also field
experiments conducted at the Jorno Kenyatta University of AgricultLKe and
technology (JKUAT) Research and Producti041 Department land and in a
farmer's field at Umuru. Gloria Fl hybrid was sown at JKUAT while
Copenhagen Market variety was sown at Umuru.
The field experiments W&fe conducted In a Completely Randomized Block
Design (CRBD) involving three treatmants and a control, with three replicates
each. The trealments comprised of applications of: - lambda-Cyhalothrin
(Karate; Bacillus /huringiensis Berliner (8t.) var. Kurstaki toxin (Dipel 2x) that
selectively kills Diamondback moth (DBM); A combination or the two pesticides
(Karate and Bt.) and UnlIeated controls. Parameters included; relative
ablXldance of the three species of aphids; their corresponding damage to
cabbage; the number of mummies per sample; pereent parasitism and the
proportions of the primary- and hyper-parasitoids hatched. The parasiloid
complex was constructed from the identified paras ito ids.
The results showed aphid counts to be higher in !'1M karate-treated plots than
in the karata-treated ones. More hyperparesitoids notably Alloxys/a sp and
Pachyneuron sp. than the only primary parasiloid (Diaeraliella rapaa) emerged
from non karale-treated plots. This might suggest that karate might have the
advantage of repelling hyperparasitolds or inhibiting their emergence. Yield
showed some negative correlation with ephid infestations. A combined
treatment gave the best ov9(all yield at both sites .
Description
Keywords
Cabbage Aphid Species