The Medfly scourge and its eradication
Editorial review 2026
The medfly: A scourge for fruit trees
A little-known application of radioactivity in the agri-food industry is the eradication of harmful insects such as the Medfly, or Mediterranean fruit fly. In fruit- and vegetable-producing countries, left to multiply naturally, these flies devastate lemon plantations and other fruit crops. The female attacks ripening fruits by depositing her eggs inside them.
© Scott Bauer/USDA (United States Department of Agriculture)
Mediterranean fruit flies, or Medflies, are a formidable scourge for fruit tree plantations in warm countries. Left to multiply naturally, these flies are capable of devastating harvests of all kinds of fruits such as lemons, apples, peaches and pears, as well as vegetables (tomatoes, peppers, avocados).
Sterilization of male cocoons
Fly larvae, like silkworms, enclose themselves in a cocoon in order to take on their final form. It is during this transformation that the cocoons containing future male flies are irradiated in order to render them sterile. These flies are irradiated in Israel, but as a remarkable example of cooperation in a troubled Middle East, some of them will be released above Jordanian orchards.
© AIEA – Biofly/Ilan Misrahi
The International Atomic Energy Agency, the IAEA, joined forces with the FAO to fight this scourge affecting not only the Mediterranean region but also all fruit-producing regions such as California, Mexico, Guatemala, Chile and Argentina. The technique used is the Sterile Insect Technique (SIT). It consists of breeding male flies that are sterilized by irradiation before being released into nature.
This birth-control technique aims to deprive wild females of offspring, leading to a significant decline in the population, or even its extinction. SIT has been used in the fight to eradicate numerous harmful insect species on every continent, notably the screwworm fly that attacks livestock, the tsetse fly and the Mediterranean fruit fly (Ceratitis capitata) or Medfly.
In the case of the Mediterranean fruit fly, the fly’s life cycle lasts about one month. The female attacks fruits during ripening by laying hundreds of eggs after piercing the skin. Within three days, they hatch into hungry larvae. The maggots devour the pulp and ruin the harvest. The larvae then transform into young flies which grow to form the next generation.
Manual release
A bag containing 7,000 Mediterranean fruit flies sterilized at the Biofly facility. Located at Kibbutz Beit Shean in Israel, the facility breeds and mass-produces these male flies sterilized by irradiation before they are released into nature. These sterile male flies placed in bags will be released manually to reach areas not covered by aerial releases. The bags carried in a truck are torn open every 100 m in the treatment area.
© AIEA – Biofly/Ilan Misrahi
From a genetically modified fly strain, specialists are able to breed only male flies after eliminating female eggs, which are more sensitive to temperature.
The larvae transform into pupae. The chrysalides are subjected to irradiation ensuring that no fertile flies are released into nature. At this stage, the male cocoons are transferred to a hatching facility. There, the adult flies emerge and feed on a sugar solution for two days. It is important that the flies released into the field are in good condition. They must be able to fly, have enough vitality to find wild female partners and survive long enough to mate.
Aerial release
This specially equipped aircraft carries a cargo of 7 million flies
which it will disperse above the Arava valley between Israel and Jordan. The aircraft flies low to disperse sterile males above villages, kibbutzim and crops – all ideal breeding grounds for the medfly. Aerial release is an effective but relatively costly method. Small aircraft precisely cover the targeted area using GPS, and the flies are released from the aircraft through a computer-controlled device.
© AIEA – Biofly/Ilan Misrahi
Releases are generally aerial, but they can also be ground-based. Most programs aim to release 20 to 100 times more sterile males than wild males with which they compete … If they are numerous enough, sterile matings lead to a dramatic drop in offspring, eventually resulting in the eradication of the scourge for the benefit of fruits, producers’ prosperity and consumers’ health.
Joint FAO/IAEA Centre of Nuclear Techniques in Food and Agriculture
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