The Mediterranean fruit fly or medfly, one of the most devastating insect pests infesting fruits and vegetables, has been successfully eradicated in the Mexican state of Colima, as announced by the Mexican authorities this week.

In cooperation with the International Atomic Energy Agency (IAEA) and the Food and Agricultural Organization of the United Nations (FAO), Mexico used a nuclear-based technique known as the sterile insect technique (SIT) to eradicate the medfly that had been threatening fruit and vegetable crops, farmers’ livelihoods and the country’s economy. 

The Colima outbreak, detected in April 2021 in the country’s largest port, Manzanillo, posed an immediate risk to crops such as carambolas, figs, guavas, mangoes, papaya, pink grapefruits and oranges. If not managed promptly, Mexico, the world’s seventh-largest producer and exporter of fresh fruits and vegetables, could face quarantine restrictions imposed by countries free from this pest. This could affect the country’s trade in such goods, which generates over 189 billion Mexican pesos (EUR 8.8 billion) annually in exports, as well as millions of local jobs.

After receiving an emergency request for assistance in April 2021, the IAEA and FAO acted immediately, dispatching expert missions to help set up and evaluate the eradication actions.

“This is one more example where SIT has been successfully used to prevent, suppress and eradicate invasive insect pests, contributing worldwide to food security and safety,” said Walther Enkerlin Hoeflich, an FAO/IAEA entomologist about a technique, which is a priority activity of the IAEA assistance for Member States, through the Joint FAO/IAEA Centre of Nuclear Techniques in Food and Agriculture.

Medfly females can damage crops by laying eggs in ripe fruits impacting the quality of products and making them unsellable and nonedible. To control the outbreak, Mexico designed and implemented an emergency action plan with the assistance of FAO/IAEA experts, delivered through the IAEA technical cooperation programme.

Based on this plan, Mexico released more than 1450 million sterile male flies in Colima using the environmentally-friendly SIT insect pest control method, which applies irradiation to sterilize insects. After being released, these males mate with wild females producing no offspring, thereby leading to a declining pest population and eventually to its eradication.

“Mexico has managed to maintain its status as a country free of the Mediterranean fly,” said Francisco Ramírez y Ramírez, General Director of Plant Health of the National Service for Agrifood Health, Safety and Quality (SENASICA) of Mexico at the event declaring the eradication of the pest in the State of Colima.

“If the Mediterranean fly had settled in the country, the consequence would have been the closure of access to national and international markets for Mexican fruits and vegetables, which ultimately would have meant economic losses for local producers,” he added.

The sterile male medflies were produced at a newly built facility in Mexico. The facility, with a design that benefited from IAEA expertise, was inaugurated in 2021. It is the second largest in the world with a production capacity of 1000 million sterile medflies every week.

The new facility, located in the state of Chiapas, focuses on mass production of sterile insects and, together with the El Pino facility in Guatemala, helps maintain the containment barrier that prevents the introduction and spread of the pest to northern Guatemala, Mexico, and the United States.

The IAEA will continue assisting and working together with Mexico through national and regional technical cooperation projects, and through Mexico’s National Fruit Fly Programme (PNMF), an IAEA Collaborating Centre.