COMPARATIVE INFORMATION ON THE LOCAL ABUNDANCE OF TWO PESTS, HELICOVERPA ARMIGERA (HÜBNER) (LEPIDOPTERA: NOCTUIDAE) AND APHIS GOSSYPII (GLOVER) (HOMOPTERA: APHIDIDAE) AND SELECTED PREDATORS ON COTTON IN EASTERN TANZANIA
Mar 13, 2017

Crop Protection WCRC Croprotection-EastSouthAfrica WCRC1
Abstract                                                                         Back to Table of contents

Seasonal occurrence of predators of Helicoverpa armigera (Hübner) and Aphis gossypii (Glover) on cotton was studied between 1989 and 1991 in eastern Tanzania. Major predators were chrysopids, coccinellids, syrphids and ants. These predators moved onto the cotton crop at flowering time, coinciding with the initial colonisation of the crop by H. armigera and A. gossypii. Coccinellids and syrphids tended to be most abundant on cotton during the first four weeks of flowering. Ants were most active between the fourth and seventh weeks following the onset of flowering. Chrysopids were most abundant midway through the flowering period.

The effect of currently used pesticides on predators was assessed in 1989 and 1991.  Endosulfan significantly reduced populations of ants and chrysopids. Similarly, use of deltamethrin significantly reduced populations of syrphids, but not of chrysopids and coccinellids. The relevance of these findings for integrated management of H. armigera and A. gossypii is discussed.

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