In the field in Zimbabwe, the behaviour of tsetse (Diptera: Glossinidae) released 10 m downwind of an odour source was studied with a video camera and with electric nets. Video studies showed that in the absence of odour, 46% of the released Glossina pallidipes Austen turn downwind and 32% turned upwind. Tsetse left the box at a constant rate. When an artificial odour mixture containing carbon dioxide, acetone, octanol and phenols was used significantly fewer tsetse, 35%, turned downwind and more tsetse, 37%, turned upwind. In the presence of odour, tsetse left the TRB later and not at a constant rate. When the TRB was placed in a complete ring of electric nets, the release of natural ox odour changed the distribution of tsetse to the downwind electric net compared to the no odour treatment. Artificial odour, with and without carbon dioxide, had no effect on the distribution of tsetse over the electric nets. The difference between the video study and the electric net study is attributed to the 50% efficiency of electric nets. We infer from the results that 10% of the tsetse departing from the TRB reacts to the presence of odour immediately.
Groenendikj C.A., Griffiths N.T. and Takken W. The initial flight direction of tsetse (Diptera: Glossinidae) exposed to natural and synthetic ox odour. Proceedings of the Section Experimental and Applied Entomology (1996) 7: 241-246.