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Averting a Fruit Fly Emergency in Mexico with a Nuclear Technique


A release box containing some 15 million sterile male fruit flies being loaded to a Cessna aircraft for release over Colima, Mexico. (Photo: DGSV Senasica)

A swift and effective emergency response, building on years of IAEA assistance, is helping the Mexican state of Colima to avoid significant economic damage from an outbreak of the Mediterranean fruit fly, also called medfly. Responding to a request for support from the Mexican government, the IAEA, in cooperation with the Food and Agricultural Organization of the United Nations (FAO), has over the last 13 months assisted national plant protection authorities in Colima in bringing the outbreak towards an end. Assistance has included developing and providing guidance for the execution of an emergency action plan using a nuclear technique which serves as a birth control for pests.

“In the past the Mediterranean fruit fly has been a big threat to the horticultural industry in Mexico and we have developed large scale programmes to defeat and contain its spread along our southern border,” said Maritza Juarez Durán, Director of the National Fruit Fly Programme of the Mexican National Service of Health, Food Safety and Quality (Senasica).

“The detection of this pest in Colima in April last year, 1,300 kilometers from the closest wild populations located in the state of Chiapas, at the border area between Mexico and Guatemala, was alarming and we value the IAEA’s and FAO’s support in helping us bring it under control.”

The implementation of the emergency action plan, supported through the IAEA´s technical cooperation programme, employs the sterile insect technique (SIT) as the main tool to eradicate the outbreak. This insect population eradication approach relies on the release of sterilized male flies. Irradiation with gamma rays was used to sterilize mass-reared medflies so that, while they remain sexually competitive, they cannot produce offspring, decreasing the population over time. The SIT is among the most environment-friendly insect pest control methods available and the IAEA supports countries, including Mexico, in reducing and eliminating medfly populations.

The Colima operation is on track and for now the outbreak is well under control. We’ll continue to work with Mexico to ensure the livelihoods of farmers remain secure from this devastating pest.
Enkerlin Hoeflich, FAO/IAEA Entomologist

A fly with consequences

Medfly (Ceratitis capitata) is considered among the most devastating insect pests worldwide due to the direct damage it inflicts on a wide range of fruit and vegetable crops. In Mexico, medfly is an invasive quarantine pest, but using the SIT, the country was able to eradicate the fly in 1982. However, the fly can cross borders easily so the country must remain vigilant to its incursions. Outbreaks of medfly can lead to strict quarantine restrictions from other countries on fruit and vegetables trade and so lead to enormous socio-economic consequences.

Mexico is the world’s seventh largest exporter of agricultural products and maintaining a medfly-free status is very important for the country. “When Mexico sounded the alarm and asked for our help, we were ready,” said Nicola Schloegl, an IAEA Programme Management Officer for Latin America and the Caribbean. Schloegl has been coordinating the IAEA’s technical cooperation support to Senasica in responding to the fruit fly outbreak. The outbreak has been recorded in a 169 square kilometre area, within a delimited area of 4,289 square kilometres where phytosanitary measures have been applied. “The country is an agricultural powerhouse, so there is a lot at stake when there is an outbreak, particularly in the current global situation where we already see rising food prices.”

In the Colima outbreak, medflies were recorded affecting fruits and tropical almonds in urban areas, posing a risk to agricultural crops such as mangoes, guavas, papaya, figs, oranges, pink grapefruits and carambolas. Mexico estimates that it produces over 189 billion Mexican pesos (EUR 8.8 billion) worth of horticultural crops for export every year that could be affected by the medfly outbreak if not brought under control.

Walther Enkerlin Hoeflich, an FAO/IAEA entomologist, was on the ground in Colima last month. He’s been supporting medfly control programmes across Latin America and the Caribbean at a technical level and provided support to Colima. He led a panel of experts who verified that the activities undertaken by Mexican authorities were implemented following international standards and helped develop recommendations to improve the operation. “Mexico’s response to the medfly outbreak in Colima was quick, professional and efficient. Their technicians are experienced in applying the SIT thanks to the long-standing cooperation Mexico has with the IAEA and FAO in using this technique,” Enkerlin Hoeflich said. The panel recommended continuing the release of sterile flies until June 2022, in order to eradicate any remaining pest population pockets.

Currently, Mexico produces over 500 million sterile medflies every week in the state of Chiapas at the country’s southern border. The mass-rearing facility there is the world’s second largest and was opened earlier this year following IAEA guidance. This facility has been the source of the 1.2 billion sterile male medflies released over Colima’s outbreak areas so far.

“The Colima operation is on track and for now the outbreak is well under control. We’ll continue to work with Mexico to ensure the livelihoods of farmers remain secure from this devastating pest,” Enkerlin Hoeflich said.

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