title: Optimal strategies for controlling riverine tsetse flies using targets: a modelling study.
abstract: BACKGROUND
  Tsetse flies occur in much of sub-Saharan Africa where they transmit the trypanosomes that cause the diseases of sleeping sickness in humans and nagana in livestock. One of the most economical and effective methods of tsetse control is the use of insecticide-treated screens, called targets, that simulate hosts. Targets have been ~1 m2, but recently it was shown that those tsetse that occupy riverine situations, and which are the main vectors of sleeping sickness, respond well to targets only ~0.06 m2. The cheapness of these tiny targets suggests the need to reconsider what intensity and duration of target deployments comprise the most cost-effective strategy in various riverine habitats.
  
  
  RESULTS
  A deterministic model, written in Excel spreadsheets and managed by Visual Basic for Applications, simulated the births, deaths and movement of tsetse confined to a strip of riverine vegetation composed of segments of habitat in which the tsetse population was either self-sustaining, or not sustainable unless supplemented by immigrants. Results suggested that in many situations the use of tiny targets at high density for just a few months per year would be the most cost-effective strategy for rapidly reducing tsetse densities by the ~90% expected to have a great impact on the incidence of sleeping sickness. Local elimination of tsetse becomes feasible when targets are deployed in isolated situations, or where the only invasion occurs from populations that are not self-sustaining.
  
  
  CONCLUSIONS
  Seasonal use of tiny targets deserves field trials. The ability to recognise habitat that contains tsetse populations which are not self-sustaining could improve the planning of all methods of tsetse control, against any species, in riverine, savannah or forest situations. Criteria to assist such recognition are suggested.
authors: Natural Resources Institute, University of Greenwich, Chatham, United Kingdom; South African Centre for Epidemiological Modelling and Analysis, University of Stellenbosch, Stellenbosch, South Africa.
authors: Glyn A
authors: GA
authors: Vale
authors: South African Centre for Epidemiological Modelling and Analysis, University of Stellenbosch, Stellenbosch, South Africa.
authors: John W
authors: JW
authors: Hargrove
authors: Liverpool School of Tropical Medicine, Liverpool, United Kingdom.
authors: Michael J
authors: MJ
authors: Lehane
authors: IRD, UMR 177 Intertryp IRD-Cirad, Montpellier, France.
authors: Philippe
authors: P
authors: Solano
authors: Liverpool School of Tropical Medicine, Liverpool, United Kingdom; Warwick Medical School, University of Warwick, Coventry, United Kingdom.
authors: Stephen J
authors: SJ
authors: Torr
mesh_terms: D000818:Animals; D003362:Cost-Benefit Analysis; D017753:Ecosystem; D006801:Humans; D007300:Insect Control / Q000191:economics / Q000295:instrumentation / Q000379:methods; D007306:Insecticides / Q000008:administration & dosage / Q000191:economics; D008962:Models, Theoretical; D011156:Population Density; D012621:Seasons; D014353:Trypanosomiasis, African / Q000517:prevention & control* / Q000662:veterinary; D014370:Tsetse Flies / Q000187:drug effects / Q000254:growth & development* / Q000502:physiology
chemical_list: D007306:Insecticides