The Sterile Insect Technique in Agricultural Crops in South Africa: A Metamorphosis …. but Will it Fly?‡

Since its humble beginnings in the late 1990s, use of the sterile insect technique (SIT) in South African crop agriculture evolved from an underfunded ‘rag and bones’ operation in Stellenbosch for a single pest, Mediterranean fruit fly (Medfly), Ceratitis capitata (Wiedemann), on deciduous fruit and table grapes, to privatized programmes for three fruit pests, viz. Medfly, false codling moth (Thaumatotibia leucotreta (Meyrick)) on citrus, and codling moth (Cydia pomonella (Linnaeus)) on apples and pears.Afourth SIT programme, for the sugarcane stalkborers, Eldana saccharina Walker and Chilo sacchariphagus Bojer, is well under development. This review focuses mainly on the Medfly SIT programme, but gives brief summaries of the development and current status of SIT for the other pests mentioned. However, many of the hardships experienced by the Medfly SIT programme have also been experienced by those people that developed, or are still developing SIT for the other pests. During the last 15 years the Medfly programme has passed through many phases and evoked many emotions, including hope, despair, misunderstanding and mistrust; but it also bred perseverance, determination, empowerment and, later, confidence. It has also included an international DNA investigation to identify the origin of a Medfly outbreak in the SIT area. The Medfly SIT programme started at Agricultural Research Council (ARC) Infruitec-Nietvoorbij in Stellenbosch in the Western Cape Province with a feasibility study over some 5000 ha of table grapes in theHex RiverValley area, releasing by air 5 million sterile male Medflies per week, produced in a run-down outbuilding with questionable equipment. Fungal rot, ant invasions, severe rust, lack of funding, inexperience and ignorance were among the challenges. The feasibility project subsequently metamorphosed into a fully-fledged, privatized programme which now produces 25 million sterile male Medflies per week in a modern, state-of-the-art facility with high-specification equipment and highly qualified technicians, distributed weekly to three different production areas and released on the ground. The current objective of the Medfly SIT programme is population suppression, but this is merely a means to an end. Medfly is regarded as a pest of international quarantine importance, and a number of countries impose strict phytosanitary measures against this pest. The ultimate goal, therefore, is the creation of Medfly-free areas, leading to sustained and expanded international fruit markets without trade restrictions due to Medfly. Many challenges still remain, but there is a fierce determination by those involved that it will succeed. In the meantime, the false codling moth SIT programme, based in Citrusdal in the Western Cape Province, is very successful and has improved and expanded significantly. The pilot release phase of the sugarcane borer SIT programme is expected to be fast-tracked after the likely procurement of an irradiator in KwaZulu-Natal in 2015. However, for economic and other reasons the codling moth SIT programme had to be terminated in 2014. ‘Will SIT in South Africa fly?’ It is already flying, but it needs to fly much higher. With the necessity to export fruit from pest-free areas, to minimize crop losses of commercial and small-scale farmers, and considering the large investments already made in SIT in South Africa, there should be no going back.