Evaluation of coloured targets for the attraction of Glossina brevipalpis and Glossina austeni (Diptera: Glossinidae) in South Africa

Abstract

Studies on the attractiveness of various coloured targets for Glossina brevipalpis and G. austeni in South Africa showed black and pthalogen blue (p.blue) combinations to be the most effective for both species. A 2 m wide (all targets 1 m high) black/p.blue/black (colour ratio 1 :2: 1) conformation caught nearly three times more G. brevipalpis and nearly five times more G. austeni than a 1,5 m wide black standard control target. For G. brevipalpis the black/p.blue/black (1 :2:1) target should be at least 2 m wide in order to increase catches significantly while a 1,5-2,0 m wide target is optimal for G. austeni. The p.blue section of a 2 m black/p.blue/black target should not make up less than 20 % of the total target width for either species. The most effective combination of practical target sizes and colour ratios were a 1,75 m wide black/p.blue/black (1 :1,5:1) or 2 m wide target (1,5:1 :1,5). Between 61-95% of G. brevipalpis and 34-90 % of G. austeni that were attracted, settled first on the black section of black/p.blue targets (> 1 m wide). Further studies revealed that for G. brevipalpis only the black parts of the 2 m wide target need to be treated with insecticide, while the entire 1,75 m wide target should be treated. For G. austeni the total width of either target should be treated with insecticide since this species readily settles on both blue and black.