Trap-orientated Behaviour of the Tsetse-Fly Glossina tachinoides (Diptera: Glossinidae)

Abstract

The behaviour of Glossina tachinoides Westwood 1850 at odour-baited and unbaited biconical traps was studied by visual observation and the use of electrocuting nets. The phenolic fraction of cow urine in combination with 1 -octen-3-ol served as olfactory attractant. Both baited and unbaited traps attract significantly more FF than MM in their vicinity, but thereof only 18% of MM and 9.3% of FF enter the trap. These %% are termed trap efficiencies; odour baiting increases them signnificantly, by 66% for MM and 94% for FF. Long-range attractiveness and efficiency of baited and unbaited biconical traps are less for G. tachinoides compared to G. morsitans group flies observed elsewhere. As 94% of landing G. tachinoides alight on the blue cone, it is recommended for tsetse campaigns that insecticide impregnation be restricted to the blue cone of the biconical trap. Up to 74% of landing tsetse alight on the lower half of the blue cone, which forms only 12% of the whole external trap surface. 500 individuals of G. tachinoides were examined for age, nutritional status and trypanosome infection. Of those tsetse-flies approaching biconical traps, there is a significant tendency for the younger and those with lower body weight and lipid content to enter the traps. These 3 physiological groups of tsetse tend also to be more strongly attracted by odours. No significant difference could be shown between trypanosome-infected and uninfected G. tachinoides relative to trap-orientated behaviour and nutritional status