The effects of odours and target colour on landing responses of Glossina morsitans morsitans and G. pallidipes (Diptera: Glossinidae)

Abstract

AbstractA laboratory bioassay was developed to allow blind testing of panels of odours for their effect on target-orientated behaviour of tsetse (Glossina spp.) in the laboratory. Landing responses of G. m. morsitans Westwood on black and blue targets were increased up to four-fold in the presence of carbon dioxide, but no significant effect of any other odours could be demonstrated. 2-methoxy phenol gave an apparent increase in landing behaviour in the laboratory, but this substance diminished rather than increased landing of G. pallidipes Austen and G. m. morsitans on targets in the field, as well as repelling tsetse from the target vicinity. Black, blue and red targets elicited strong landing behaviour in male G. m. morsitans in the laboratory, and white and yellow targets elicited little or none, whether carbon dioxide was present or not. In the field, high ultraviolet reflectivity increased landing behaviour of G. pallidipes, but only when there was a proportion of transmitted light through the target. Ultraviolet reflectivity always reduced overall attraction of tsetse to a single-coloured target. Two-coloured targets incorporating ultraviolet-reflecting white cloth obtained strong landing on the white panels, but caught fewer flies overall than all-black, or blue-and-black targets.