Johannesburg – South Africa exported a record 203.4 million 15-kilogram cartons of citrus in 2025 – around 2.9 million tonnes in total.
Export volumes were reported to be 22% higher than in the previous season, making South Africa the world’s largest citrus exporter by volume.
That success also raises the stakes for the industry: access to global markets depends not only on orchards, packhouses and ports, but also on the ability to manage pests before fruit leaves the farm.
For South Africa’s fruit exporters, pests are more than a threat to individual crops.
A phytosanitary problem can disrupt supply chains, increase compliance costs and, in serious cases, place market access at risk.
Before a South African orange, peach or bunch of grapes can enter an export market, it must comply with that destination’s phytosanitary requirements.
These rules are intended to prevent agricultural pests from crossing borders and becoming established in new environments.
For exporters, a single pest interception can mean additional inspections, treatment requirements, shipment delays or, in some circumstances, rejection.
The Mediterranean fruit fly, or Medfly, is one of the pests that can create this kind of risk.
It affects a wide range of fruit crops, damaging produce and reducing yields. Even where on-farm damage is limited, the consequences can extend further if a trading partner detects a pest in an imported consignment.
Insecticides remain an important crop-protection tool, but growers are under increasing pressure to manage pests effectively while reducing unnecessary reliance on chemical treatments.
The Sterile Insect Technique (SIT) can play a role as part of an integrated pest-management programme.
The principle behind the SIT is straightforward, even if it initially sounds counterintuitive.
Male insects are bred in specialised facilities and sterilised using irradiation before being released into areas where wild pest populations are present.
They continue to compete for mates, but the matings do not produce viable offspring.
If sterile males are released in sufficient numbers over time, the target pest population can decline.
In the SIT process, irradiation is applied to insects, not to harvested fruit.
Because the method targets a specific pest, it can complement monitoring, orchard sanitation and other conventional crop-protection measures.
South Africa has been developing this approach for more than two decades, particularly in the Western Cape.
What began as a pilot effort has evolved into a large-scale pest-management programme involving researchers, public institutions and commercial fruit producers.
The scale is striking. According to the International Plant Protection Convention, sterile male Mediterranean fruit flies were being produced at a rate of around 65 million a week by 2023.
During the main season, releases covered roughly 40 000 hectares of commercial deciduous fruit and table grapes every week.
In areas covered by the programme, average wild Medfly populations fell by 73 per cent.
For growers, these figures are about more than scientific success.
Fewer pests can mean less damaged fruit, reduced pressure to use insecticides and a lower risk that a pest problem will follow a shipment beyond the farm gate.
The experience also shows how nuclear science can become part of wider agricultural cooperation.
In Mauritius, with support from the International Atomic Energy Agency, infrastructure has been developed to produce sterile fruit flies and strengthen national capacity to combat agricultural pests.
The country is also developing training opportunities for specialists from other African states.
But irradiation alone is not a magic solution.
As South African entomologist Brian N. Barnes wrote: “SIT in South Africa has been more successful in some areas than in others, but the programme continues to evolve based on the many valuable lessons that have been learnt.
“For SIT to be effective there must be sustained funding, no compromise in quality, and good management, communication and training for the staff involved.”
Building this kind of capacity can also benefit from international technical cooperation.
Countries developing radiation-based applications for agriculture can draw on experience in facility design, irradiation technology, quality assurance and staff training.
Organisations including the IAEA, research institutions and technology providers have supported such capacity-building efforts in different regions.
In Bolivia, for example, the national nuclear energy agency and public-health institutions have used gamma irradiation to sterilise mosquitoes that can transmit diseases including yellow fever.
The work was carried out at the country’s Multipurpose Irradiation Centre, using irradiation technology supplied through Russia’s Rosatom.
Although the Bolivian project addresses vector-borne disease rather than fruit pests, it demonstrates the broader use of irradiation-based sterile-insect methods.
In agriculture, the same underlying approach can support pest-control strategies when it is integrated with local surveillance, regulation and crop-management practices.
Radiation technologies have potential beyond sterile insects, too.
Irradiation can be used to treat food and agricultural products, helping control pests, improve food safety and extend shelf life.
International organisations and technology developers are exploring ways to use these applications to reduce post-harvest losses and strengthen food supply chains.
For consumers, all of this may seem far removed from the simple experience of buying a bag of grapes or peeling an orange.
Yet behind that ordinary moment is a complex chain of farmers, scientists, inspectors, exporters and technologies working together to make sure the product is safe, meets the phytosanitary requirements of its destination market and can move smoothly across borders.
For South Africa’s fruit industry, effective pest management is becoming part of the infrastructure that underpins international trade – alongside cold chains, packhouses, traceability systems and port logistics.
