Short communications

Laboratory assay to determine efficacy of insecticides for control of the spotted maize beetle, Astylus atromaculatus Blanchard (Coleoptera: Melyridae), a pest of sorghum

Published in: South African Journal of Plant and Soil
Volume 18, issue 3, 2001 , pages: 136–138
DOI: 10.1080/02571862.2001.10634418
Author(s): H. du Plessis, South Africa, J. van den Berg, South Africa

Abstract

Spotted maize beetle, (Astylus atromaculatus), African boll- worm, (Helicoverpa armigera) and various aphid species attack sorghum from flowering onwards. The possibility of simultaneous control of these pests with a single application of an insecticide exists. The efficacy of insecticides registered for the control of aphids, A. atromaculatus and H. armigera on grain sorghum was evaluated for control of A. atromaculatus. Significant differences in efficacy were observed but most insecticides were ineffective. Gamma-BHC was only 53 % effective, but methomyl, registered for control of H. armigera was 100 % effective after 72 hours. Since the residual action, based on the withholding period of methomyl is short and the possibility of reinfestation by beetles under field conditions exists, control may not be effective over the long term.

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