Orientation of tsetse flies to wind, within and outside host odour plumes in the field

Abstract Free‐flying wild tsetse flies (Glossina pallidipes Aust. and G. m. morsitans Westw.) were video recorded in Zimbabwe as they flew within an artificial host odour plume at 3, 7 or 15 m from the source, or in no odour, with and without a 0.75 m2 vertical, black visual target present aligned with the wind. With no visual target present, flights in odour were strongly biased upwind, and in the absence of odour strongly biased downwind. With the target present, between 16% and 40% of the upwind approaching flies responded visually as they passed the target, by circling it, in proportion to the proximity of the source (taken to be proportional to the mean odour concentration). Crosswind approaching flies (for whom the target will have been visible for some metres away) circled more frequently (34–56%), but without obvious correlation with the odour concentration. Circling flies also responded orthokinetically, by slowing down as they passed the target. The departure directions relative to the wind of flies leaving the target were significantly affected by the odour concentration. At 3 m they left the target in all directions, except possibly avoiding due upwind. At 7 m they left with an obliquely upwind bias, but at 15 m and also in no odour, they left with a strong crosswind bias.

[1]  J. Kennedy.  Zigzagging and casting as a programmed response to wind‐borne odour: a review , 1983 .

[2]  J. Brady.  The circadian organization of behavior: timekeeping in the tsetse fly, a model system , 1988 .

[3]  M. Warnes.  Responses of tsetse flies (Glossina spp.) to compounds on the skin surface of an ox: a laboratory study , 1989, Medical and veterinary entomology.

[4]  G. Gibson,et al.  ‘Anemotactic’ flight paths of tsetse flies in relation to host odour: a preliminary video study in nature of the response to loss of odour , 1985 .

[5]  M. J. Packer,et al.  Odour movement, wind direction, and the problem of host‐finding by tsetse flies , 1989 .

[6]  E. Bursell,et al.  An energy budget for Glossina (Diptera: Glossinidae) , 1980 .

[7]  S. Torr.  The flight and landing of tsetse (Glossina) in response to components of host odour in the field , 1988 .

[8]  J. Murlis,et al.  Fine‐scale structure of odour plumes in relation to insect orientation to distant pheromone and other attractant sources , 1981 .

[9]  S. Torr.  Behaviour of tsetse flies (Glossina) in host odour plumes in the field , 1988 .

[10]  G. Gibson,et al.  Visually‐guided, upwind turning behaviour of free‐flying tsetse flies in odour‐laden wind: a wind‐tunnel study , 1989 .

[11]  The effect of wind‐borne odours on the direction of flight in tsetse flies, Glossina spp. , 1987 .

[12]  G. Gibson,et al.  Flight behaviour of tsetse flies in host odour plumes: the initial response to leaving or entering odour , 1988 .

[13]  G. Vale.  Flight as a factor in the host-finding behaviour of tsetse flies (Diptera: Glossinidae). , 1980 .

[14]  E. Bursell,et al.  Observations on the orientation of tsetse flies (Glossina pallidipes) to wind‐borne odours , 1984 .

[15]  G. Vale.  Artificial Refuges for tsetse flies ( Glossina spp.) , 1971 .

[16]  D. Hall,et al.  The role of 1-octen-3-ol, acetone and carbon dioxide in the attraction of tsetse flies, Glossina spp. (Diptera: Glossinidae), to ox odour , 1985 .

[17]  Thomas C. Baker,et al.  Field and laboratory electroantennographic measurements of pheromone plume structure correlated with oriental fruit moth behaviour , 1989 .

[18]  Stephen J. Torr,et al.  The host‐orientated behaviour of tsetse flies (Glossina): the interaction of visual and olfactory stimuli , 1989 .

[19]  J. Borden,et al.  Distant olfactory response of the onion fly, Delia antiqua, to host‐plant odour in the field , 1989 .