Strategic and tactical developments in tsetse control in Zimbabwe (1981–1989)

Abstract

Tsetse flies have been eradicated from an area of 48,000 km 2 in Zimbabwe since 1981. The main approach has been pesticidal control, involving ground spraying, aerial spraying, cattle dipping and artificial bait techniques, in some circumstances in combination. This represents a change in tactic from the pre-independence period when control relied solely on ground spraying. Factors which have influenced choice of technique are discussed in the paper, including scale of trypanosomiasis problem, technical limitations of the technique, cost-effectiveness and environmental considerations.Ground spraying, the mainstay of tsetse control operations in Zimbabwe prior to 1980, is becoming increasingly unfavourable because of high logistical requirements and environmental reasons, but remains an effective technique under a wide range of circumstances. Aerial spraying has proved very effective for management of crisis situations but is comparatively expensive, capital intensive in hilly terrain and less effective against Glossina pallidipes than G. morsitans. Vector control by applying insecticide (deltamethrin) to cattle appears technically feasible at a very competitive cost. This is a most promising technique hi areas where there are already cattle and few wild hosts.Control of tsetse using odour-baited and insecticide-treated screens has proven technically feasible in a wide range of terrain, and appears economically competitive with ground spraying. Both technical and financial performance of the technique are still being improved. Bait technology offers scope for the new approaches to the control of the fly and defence of cleared areas from reinvasion. Resume-Les mouches tse-tse ont ete eradiquees sur une superficie de 48.000 km 2 au Zimbabwe depuis 1981. La principale approche a ete le controle avec 1'utilisation des pesticides, notamment la pulverisation terrestre, la pulverisation aerienne, les bains du betail et les techniques d'appat artificiel et dans certains cas une combinaison de ces techniques.Ceci represente un changement dans la methode de la periode pre-independance durant laquelle le controle etait exclusivement la pulverisation terrestre. Les facteurs qui ont abouti au choix des techniques sont discutes dans cette publication y compris la dimension du probleme de la trypanosomiase, les limitations de la technique, les aspects cout-efficacite et les considerations des facteurs de I'environnement.La pulverisation terrestre, principal atout des operations de contrdle de la mouche tse-tse avant 1980, est de moins en moins favorisee a cause de son cout eleve, de la forte demande en logistique et pour des raisons de sauvegarde de I'environnement, demeure cependant une technique efficace en d'autres circonstances.La pulverisation aerienne s'est revelee tres efficace pour gerer des situations de crise mais 399

Modelling the spatial-temporal distribution of tsetse (Glossina pallidipes) as a function of topography and vegetation greenness in the Zambezi Valley of Zimbabwe

“…The study area is located in north western Zimbabwe at 16˚ south and 29˚ east 141 the study region and this has resulted in the tsetse front progressively receding 167 towards the Zambezi River (Shereni, 1990). 168…”

Evaluation of insecticide‐treated cattle as a barrier to re‐invasion of tsetse to cleared areas in northeastern Zimbabwe

“…In Zimbabwe over recent years, a combination of tsetse control methods has successfully eradicated the fly from large parts of the country’s interior, leaving infestations in the northeastern Zambezi valley and along the eastern border with Mozambique ( Shereni 1990). As a result, a large proportion of the tsetse control budget in Zimbabwe (20%) is now spent on maintaining the barriers to tsetse re‐invasion from neighbouring countries ( Shereni 1990). These barriers consist of odour‐baited insecticide‐treated control targets in a band ≈ 8 km wide, at an operational density of four per km 2 ( Hargrove 1993).…”

Trypanosome infection rates in tsetse flies (Diptera: Glossinidae) and cattle during tsetse control operations in the Kagera River region of Rwanda

“…populations through the use of insecticideimpregnated targets (Vale et al, 1988), insecticide-treated cattle, (Shereni, 1990) and odour-baited traps (Dransfield et a\., 1990) have suggested the possibility of achieving practical levels of trypanosomiasis control without the necessity of eradicating tsetse flies. These new techniques may reduce disease incidence in most areas where mechanical transmission of trypanosomes by biting flies is not a significant factor (Wells, 1972).…”