Coordinated research and focus on sterile insect technology can contribute to tackling livestock pest

The International Atomic Energy Agency (IAEA) and Food and Agriculture Organization of the United Nations (FAO) are stepping up efforts to contain and suppress the re-emergence of New World Screwworm in Central America, Mexico and the United States of America through the application of a nuclear technique.

The New World Screwworm (NWS) is a parasitic fly whose larvae infest warm-blooded animals. Female flies lay eggs in open wounds or mucous membranes, and once hatched, the larvae burrow into living tissue, enlarging wounds and causing infections that can be fatal if untreated. After decades of successful eradication, the pest has re-emerged in Central America and Mexico and was confirmed in the United States in early June 2026 — the first occurrence there in more than 40 years.

The Coordination Research Project (CRP) launched Thursday will help countries use the sterile insect technique capacity to halt the NWS’s re-invasion. Sterile insect technique (SIT) uses radiation to sterilize insects, which are then released to mate with wild populations and produce no offspring, helping suppress pest populations over time. The SIT was central to the eradication of NWS from the United States, Mexico and Central America, when a 45-year campaign eradicated the pest from the US in 1982 down to Panama in 2006, with sterile flies used to maintain a barrier in the Darién Gap in Southern Panama. The barrier was effective until 2022, when the fly began spreading northward from Panama.

The parasite’s recent resurgence poses a serious threat to livestock, animal welfare, wildlife and public health, with potentially severe socioeconomic consequences. On 3 June, the United States confirmed its first animal case of NWS in more than 40 years, following the pest’s progressive re-emergence in Central America and Mexico. Changing weather patterns, globalization and unlawful transboundary animal movements have contributed to the pest’s spread, creating new challenges for countries working to contain it.

A Major Threat to Livestock and Economies

Infestations can kill animals, damage hides, and reduce milk and meat production. The previous eradication was estimated to have generated annual benefits of $1.3 billion for livestock producers in the United States, Mexico and Central America.

“The return of New World Screwworm is already causing serious damage in the region, threatening animals, livelihoods and economies,” said IAEA Director-General Rafael Mariano Grossi. “Through nuclear science and technology, and by coordinating with a new generation of researchers, the IAEA is helping countries strengthen the tools they need to detect, suppress and ultimately control this devastating pest.”

The new CRP will bring together leading experts from more than 20 affected countries – including some in South America where NWS is endemic – to strengthen fly surveillance and control methods, improve mass-rearing and sterilization, study mating compatibility and competitiveness, and support the release of sterile flies.

“The New World screwworm outbreak in Central America, Mexico and the United States is a timely warning that pests and diseases never respect territories, and addressing this reemerged threat across boundaries requires vigilance, international cooperation, and sustained coherent management in monitoring, science, and innovation. Through the Joint FAO/IAEA Centre and under the new Coordinated Research Project, we are strengthening proven tools such as the sterile insect technique, which has successfully eradicated this pest in the past, including in Libya, to help countries protect livelihoods and build more resilient agrifood systems,” noted FAO Director-General QU Dongyu.

Responding to the current outbreak could require up to 600 million sterile flies per week, but emergency response efforts are facing a shortage of sterile flies. The US-Panama commission (COPEG) facility in Panama – the only operational facility mass-rearing and sterilizing NWS – now produces about 100 million per week, while expanded capacity in Metapa de Dominguez, Mexico, and Mission, Texas, could add up to 400 million per week in the coming years.

The five-year project, with a planned budget of US $1 million, will include improving tools and methods for mass-rearing, sterilization and release of flies.

“To meet the needs of greater numbers of sterile flies, the project will bring together expertise to improve the cost-effectiveness of mass-rearing, developing and managing screwworm strains, enhancing handling and release methods and studying mating behaviour and competitiveness,” said Rui Cardoso Pereira, head of the Insect Pest Control Section at the Joint FAO/IAEA Centre.

With sterile fly production currently insufficient to halt the spread, the results of the project will help Member States optimize the use of sterile flies to control the NWS. The threat posed by NWS and other transboundary diseases requires a collaborative approach that integrates surveillance systems for early detection, improved laboratories and diagnostics, and trained veterinarians and animal health workers. Together, these efforts help countries share information quickly when disease threats emerge and support effective emergency response planning. SIT has been a major subject of the Joint FAO/IAEA Centre of Nuclear Techniques in Food and Agriculture for over 60 years. It involves both applied research to improve the technique and develop it for new pest insects; and the transfer of the SIT package to Member States.