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California´s Terminator

California Medfly

The Medfly´s nemesis is nuclear science - namely, a spin-off technology known as the sterile insect technique, or SIT, that´s used alongside other pest-control measures. (Photo: D. Calma/IAEA)

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News Flash, September 2004:
"Medfly Infestation Threatens San Diego County"
"Aerial Releases of Sterile Medflies to Begin in San Diego County"

San Diego, USA -- Californians have been battling the Medfly since Ronald Reagan governed the golden state. The invasive pest is among the worst threats to the state´s multi-billion dollar fruit and agricultural industry.

"If the Medfly were to become permanently established, the estimated economic loss would be as much as $1.9 billion annually," warns the California Department of Food and Agriculture.

That´s more than the gross domestic product of many countries in the world. Just one fly´s mere presence triggers market alerts from Sacramento to Saskatchewan to Sapporo - together Canada and Japan buy more than half of all fresh fruit the USA exports.

So the little fly is a big deal. It´s nearly as dangerous to politicians as it is to pears, pomegranates and many kinds of fruit.

In 1982, a Medfly outbreak threatened California fruit farms and helped spell the end of then-Governor Jerry Brown´s bid for election to the United States Senate. Pundits say the Governor mishandled the fight against the fly, sending his approval ratings downhill. He lost the Senate race.

Today, the Medfly menace challenges California Governor Arnold Schwarzenegger, the former Hollywood actor of "Terminator" movie fame. The Governor teamed with state Secretary of Agriculture A.G. Kawamura in 2004 to take on a high-profile Medfly case. An outbreak in Baja California, Mexico, threatened San Diego County about seven miles across the border.

The news triggered emergency actions from Tijuana to El Paso. Californians quickly partnered with authorities from Mexico, the US Department of Agriculture´s Animal and Plant Health Inspection Service (APHIS), and border and customs officials in Texas, Arizona, and New Mexico to stop the Medfly´s advance. Controls and quarantine restrictions were put in motion that lasted for nine months before the emergency was declared to be over.

Among the modern tools of combat: the sterile insect technique (SIT), a form of biological birth control that´s become quite a "terminator" itself. Male Medflies are factory-reared and sterilized, then released by air to saturate threatened areas. The result: a stacked deck when it comes to mating - sterile males mate unproductively with any females around - and Medfly populations are terminated.

Against the 2004 San Diego threat, 15 million sterile Medflies reared at APHIS facilities in Hawaii and Guatemala were flown into southern California, then systematically released by air over San Diego County and Tijuana, Mexico for weeks to infiltrate target zones. The steps were part of California´s emergency plan under an anti-Medfly programme set up in the mid-1990s to guard against infestations. The SIT has won favour because it works well in combination with fly-trapping and other area-wide tools to fight pests and specifically cuts down on the use of chemical sprays.

No Medfly ever made it into southern California in 2004.

"The Medfly is a serious threat to agriculture that demands quick action," says California Secretary Kawamura. "Sterile Medflies are an outstanding, environmentally responsible tool for combat against a major pest."

Winning Multinational Teams

The IAEA has helped California authorities beat the Medfly. Scientists in the Joint Programme that the IAEA runs with the UN Food and Agriculture Organization (FAO) support SIT research and provide technical and scientific advice. Mr. Jorge Hendrichs, an entomologist from Mexico who heads the Insect Pest Control Sub-Programme, sits on the board of California´s Medfly science advisory panel.

A veteran of anti-Medfly and SIT campaigns, he credits sustained and steady efforts for winning the fight against the Medfly. The first large SIT campaign targeting the pest was in 1977 in southern Mexico. The fly had invaded Costa Rica in the 1950s and made its way through other Central American countries, threatening their Medfly-free status.

"The US announced it would close its border to Mexican fruits and vegetables if the Medfly crossed the Isthmus of Tehuantepec near the Guatemala border," Dr. Hendrichs recalls. "An emergency programme was launched, integrating pest suppression tools with the first large-scale application of the SIT."

The multinational project - known as Moscamed, Spanish for Medfly - stopped the fly´s northern spread by 1982, effectively creating a buffer zone saturated with sterile flies. The SIT barrier has worked for three decades, keeping northern Guatemala and Mexico, and indirectly the USA, free of the Medfly. Today Project Moscamed produces over two billion sterile male flies a week in Guatemala at the El Pino facility, the world´s largest Medfly rearing plant. The factory supplies SIT campaigns in Guatemala, Mexico, USA, and other countries.

Today the risks to Mexico´s $3-billion fruit and vegetable export business and the USA´s huge agriculture markets remain high.

In the USA, a $60 million strategic plan targets the Medfly and other exotic fruit flies. The aim is to protect more than $7 billion worth of US fruit and agricultural crops - mostly in California, Florida, and Texas - susceptible to fruit fly infestation.

In California, a particular target of Medfly prevention is the bustling Los Angeles area. Multiple commercial air and shipping ports sharply raise the risk of pests entering the state via travel and trade.

"The preventive release programme started in 1996 and today keeps more than 6000 square kilometres of the Los Angeles Basin area free of the Medfly," Dr. Hendrichs says. The SIT became a staple tool following public opposition to pesticide spraying campaigns over urban areas.

Though Medflies continue to be detected in the LA area from time to time, no major outbreaks have occurred for more than a decade. That´s both an indication of the programme´s results and of the constant threat the Medfly poses to California fruit.

"We know the SIT strategy has been successful technically, politically, and environmentally," Dr. Hendrichs says. "While no silver bullet, it´s a valuable weapon against pests that can ravage crops and threaten a nation´s agricultural economy." -- Lothar Wedekind, IAEA Division of Public Information.