Development of the Sterile Insect Technique to Suppress Thaumatotibia leucotreta (Lepidoptera: Tortricidae) in Citrus Fruit: Commercialisation and Expansion (Part 2)

Progress since 2007 with the commercial implementation of the sterile insect technique (SIT) for Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) in citrus orchards in South Africa is discussed. To enable expansion of the SIT programme, rearing equipment was developed and adapted where necessary. Production monitoring systems for traceability, cold chain management and quality management of reared insects were developed and constantly improved. The initial 3300-ha SIT-treated area in the Citrusdal region was increased to 4800 ha by incorporating parts of the Olifants River Valley and sterile insect releases were also introduced into 6500 and 2200 ha of the Sundays River and Gamtoos River Valleys (Eastern Cape Province), respectively. There was a progressive, seasonal improvement in wild T. leucotreta suppression following routine releases of sterile moths in all areas treated, resulting in reduced crop losses and fewer rejections for T. leucotreta in export fruit. The SIT for T. leucotreta was also expanded to the Hex River Valley (Western Cape Province) and the Lower Orange River area (Northern Cape Province) in 2016.