EVALUATION OF A VIRUS INSECTICIDE COMBINATION FOR COTTON PEST-CONTROLIN TOGO

A low dose of cypermethrin combined with Mamestra brassicae virus was applied weekly against the bollworms Helicoverpa armigera (Hubner) and Diparopsis watersi (Rothschild) in smallholder cotton plots in northe rn Togo in 1989 and 1990. The timing of treatments was based on action thresholds. One or two additional sprays of Bacillus thuringiensis we re applied to control Syllepte derogata F., or dimethoate to control a phids. No significant yield differences were observed between the plot s treated with the pyrethroid-virus combination and the control plots, treated with the recommended insecticide schedule. However, the latte r had a significantly higher percentage of healthy bolls. The virus ap plied was not reisolated from insects collected in the field.