Principles of area-wide integrated tsetse fly control using the sterile insect technique

Abstract

The tsetse fly and the disease trypanosomosis it transmits, is one of the most severe medical and veterinary problems in Africa, infecting around 50,000 people every year and preventing the development of sustainable and productive agricultural systems. The most efficient way to contain the disease is by the management of entire populations of the vector (area-wide approach) using a combination of several control methods in an integrated pest management campaign. A very powerful method for integration in these programmes as a final eradication component is the sterile insect technique (SIT). The technique relies on the rearing of the target insect in large numbers in specialised production centres, the sterilisation with ionising radiation of one of the sexes and the sustained sequential release of the sterilised insects over the target area. Contrary to conventional control methods, the sterile insect technique becomes more efficient with decreasing density of the target population. Hence, the technique fits well within the concept of integrated pest management, as its complementary use in a phased approach with other suppression techniques, results in maximum efficiency. The five main prerequisites required to use the sterile insect technique against a target insect have been achieved for tsetse flies: 1. adequate information on the ecology of the insect is available, 2. the mass-production of the target insect is economically feasible, 3. efficient suppression techniques are available to reduce the population density of the target insect, 4. sufficient sterile males are available for release and their competitiveness is optimal, 5. the gamma treated sperm is competitive with the wild sperm. This paper gives a detailed review of the five implementation phases of the sterile insect technique based area-wide integrated pest management campaign against Glossina austeni on the island of Unguja, Zanzibar. The potential future prospects and requirements of using the sterile insect technique against tsetse populations are likewise presented.