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Vector control

Most tsetse suppression measures are based on the use of insecticides. Delivery methods for insecticidal attack of tsetse consider four main forms:

  • depositing residual insecticide, either discriminatively (on to the resting and breeding sites of tsetse by ground spraying) or less selectively (treating the entire habitat from the air);

  • application of insecticides on animals (epicutaneous use, the so-called pour-on or live-bait technique);

  • repeated spraying of non-residual insecticide, either over large areas using aircraft (sequential aerosol technique - SAT) or in more localized areas using hand held or vehicle mounted fogging machines;

  • attracting tsetse to devices such as screens or traps treated with persistent insecticide (artificial techniques).

A very specific, non-polluting method is the use of Sterile Insect Technique (SIT). Males of tsetse flies are rendered sterile by gamma irradiation. Tsetse females that mate with sterile males will not produce offspring, as tsetse females normally mate only once in their life, contrary to males. Hence, with the continuous release of sterile males in large numbers it is possible to eliminate tsetse flies from a given area. Aerial fly release facilitates a homogeneous and area-wide dispersal of the sterile insects. For increased effectiveness, the sterile males should significantly outnumber the fertile native, wild male flies. Financial cost of insecticide applications is less related to the insect population density, while it depends more on the size of the area to be treated. Insecticide applications are thus most cost-effective when target population density is high in a sufficiently large area. On the contrary, the SIT is most cost-effective when the target population density is low. This suggests that a phased and integrated, complementary use of both `conventional` methods and SIT would result in maximum efficiency of the intervention.

Comments: AGA-Webmaster