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Chile´s Leading Edge

California Medfly

Many weapons are needed to fight fruit flies and other agricultural pests. Alongside the SIT technology, vigorous control campaigns target and suppress the Medfly. (Photo: L. Wedekind/IAEA)

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Arica, Chile -- In this famed city of "eternal spring", the sun shines long and rain is rare. Averaging less than a millimetre a year, precipitation tends to be remembered in drops per decade. In one stretch, no rain fell for 14 years.

Bordering Peru on Chile´s northern Pacific shore, Arica is home to a quarter of a million people living along wide sandy shores and thin slices of green land in the Lluta and Azapa Valleys. Olives, vegetables, and varied fruits are grown there, fed by water pumped from deep below the ground.

Twice a week every week, Paula Troncoso-Kirsten oversees an air campaign to protect oasis crops from unnatural enemies. Hundreds of marked bags, each filled with 8000 sterile male Medfly pupa, are dropped systematically by airplane to rain on target zones in orchards, fields, and backyards.

The flies are factory-reared biological agents, sent as part of the area´s pest prevention programme to mate with any female Medflies around. The males nearly always end up disappointed. Even if they did find a willing partner, the mating would end up being... well, fruitless.

"No Medflies naturally exist in this arid environment or anywhere in Chile," explains Ms. Troncoso-Kirsten. She heads the Arica Operations Centre of Chile´s agricultural and livestock service, called SAG, and runs the region´s Medfly prevention programme. Any Medflies found here are unwanted intruders that tourists or travellers bring in.

She leads teams that works closely with authorities in southern Peru, where Medfly pockets are known to exist, to contain the fly´s movement. The countries rely upon a method known as the sterile insect technique (SIT) that was developed with support of the IAEA and UN Food and Agriculure Organization (FAO).

The flies raining in Arica skies are homegrown at the nearby Sterile Insect Production Centre, Chile´s only SIT facility, in Lluta Valley. The $2-million centre opened in 1993 with technical and financial support from the IAEA, United Nations Development Programme and Inter-American Development Bank.

Inside, teams of specialists rear about 35 million Medflies each week, using the latest methods. They produce a genetic sexing strain that enables rearing of only male flies. Chile´s SIT plant supplies the weekly Arica air campaigns and those in Peru´s Tacna region across the border.

IAEA-supported technical cooperation projects transferred the SIT technology to Peru, Chile and other countries over the past decades. Today, specialized training continues at IAEA research laboratories in Seibersdorf, Austria.

"We´re applying the latest technology for a programme that´s very important to our national development," says Mr. Carlos Sarabia, the plant´s manager. "The work we do here has benefited a great deal from IAEA and FAO expert support."

Chile is among the world´s top fruit producers and exporters. No country in South America sells more fresh fruit and vegetables overseas, and Chile´s earnings top $2 billion per year from their export.

"The success we´ve had against fruit flies is the driving force for our fruit and vegetable industry. It shows the value of international cooperation and our bi-national control efforts with Peru and collaboration with Argentina and other neighbours," says Mr. Jaime Gonzalez, an agricultural engineer and entomologist. Based in Santiago, he heads SAG´s nationwide fruit fly programme.

The country has fought the Medfly for nearly 40 years. The majestic Andes and long stretches of drylands geographically protect the country from the fly´s presence. But the Medfly came into the South American region more than a century ago, and tourism, trade, and traffic can keep it moving. The pests can ruin harvests by injecting their eggs into maturing fruit and vegetables.

Chile has had to win the "fly wars" more than once, Mr. Gonzalez points out. The first eradication campaign started in the late 1980s, through a national programme initiated and funded in large part by Chile´s fruit growers and supported by the IAEA. Initially, Chile imported sterile Medflies from SIT facilities in Hawaii, Guatemala, and Mexico and released them across Arica, where the pest was found. Field results were so impressive that Chile decided to build its own plant.

By December 1995, the country had officially won its first long battle. Chile was officially declared a "fruit-fly-free" country, only to have to regain certification five years later.

Efforts were redoubled in 2000 when 193 invading Medflies were detected in the Arica area. Emergency measures kicked in - including intensified monitoring, trapping, and sterile fly campaigns supplied by the Arica plant - to thwart the threat.

Since the 2000 victory, only one fly has been detected, in 2004. Arica was again declared "fruit-fly-free" in December that year. The certification expanded markets for Chile´s fruit growers, shippers, and laborers. Exports of fruit from apples and kiwi to cherries and grapes are again running higher than ever.

"Chile is in a leading position as a fruit-fly-free country. As a result, we can export fresh fruit to markets that are closed to countries plagued by Medfly infestation," says Mr. Gonzalez. "But we´ve had to succeed more than once against the Medfly. The experience shows how constant the threat can be." -- Lothar Wedekind, IAEA Division of Public Information