• English
  • العربية
  • 中文
  • Français
  • Русский
  • Español

You are here

Science, Sex, Superflies

20 April 2007
In Argentina, Chile, Mexico, Guatemala and the United States, the battle of the sexes is a profitable affair.Smaller than your little finger, the Mediterranean Fruit Fly -- Medfly, also known as Ceratitis capitata in science speak -- doesn't look like a roaming threat.  But it is, ranked among the world's most destructive food pests, a transboundary superfly of ruin. (Credit:  Scott Bauer/USDA)In the USA, the Medfly is on the most wanted list of trade foes: its DNA genetic code is registered with food safety regulators, who use it to track the origin of Medfly outbreaks. In California, the invasive pest threatens the state's multi-billion dollar fruit and agricultural industry, and challenges politicians and fruit growers alike. A recent outbreak was prevented under the watch of Governor Arnold Schwarzenegger, shown here in front of his giant image as Hollywood's cinematic "Terminator" while promoting the state's agricultural products in Japan. (Credit: Getty Images)The Medfly attacks all kinds of ripening fruits, including apples, peaches, pears, cherries, figs, and 200 other crops potentially worth billions of dollars in the marketplace. The photo shows a street market in Valparaiso, Chile, where local crops, deemed ripe and safe for sale, are on offer. (Credit:  Wedekind/IAEA)The Medfly spreads mainly through the movement of infected fruit. Quarantine laws, travel checkpoints and pest control programmes regulate food trade and movement and restrict the Medfly's reach.  Regulators apply old and new tools-of-the-trade - from sex-based insect lures to fruit-sniffing beagles and X-ray detectors -- to keep pests out and under control. (Credit:  Wedekind/IAEA)Left alone, the fly's lifecycle ruins crops.  In about a month's time, the female fly lays hundreds of eggs inside fruit. Within three days, they hatch into hungry, wormy larvae, or maggots, that devour the pulp and kill the crop. Emerging pupae then grow to become the next generation of fly.  (Credit:  Wedekind/IAEA)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. The idea is biological birth control: by producing a genetic sexing strain of the fly species, specialists are able to rear only males flies at SIT facilities. They sterilize them using precise doses of radiation, then release them into target areas, where they mate "fruitlessly" with any females they encounter. Over time, the fly population is suppressed and even eradicated. (Credit: Calma/IAEA)The IAEA and The Food and Agriculture Organization (FAO) have spearheaded SIT research and development for the Medfly and other insect pests, including tsetse flies posing health risks to livestock and humans.  The two agencies jointly run programmes and laboratories that help countries apply nuclear-based techniques in fields of agriculture.  At the IAEA Seibersdorf Laboratories, entomology technician Rudy Boigner checks a panel of tsetse flies. (Credit:  Calma/IAEA)Today, Argentina, Chile, and dozens of other countries -- including the United States, Brazil, Mexico, South Africa, Spain, Israel, Jordan, Peru, and Guatemala -- rely on SIT production centres to win battles against the Medfly.  The centres collectively produce 3.5 billion male flies a week for control campaigns.  In Chile, a SIT centre in the northern port city of Arica is the backbone of operations to keep the region and country Medfly free.  The plant was built and staff trained with IAEA/FAO support in the early 1990s.  The fly was eradicated a few years later. Plant chief Carlos Sarabia (third from left) and team produce more than 20 million sterile male flies each week for use in Arica and neighbouring Peru. (Credit:  Wedekind/IAEA)Flies reared at SIT centres are marked with a fluorescent dye during production to make them easy to spot and identify under blacklight later.  That's important for verifying that the flies have been mass-reared and sterilized.  (Credit:  Calma/IAEA)Fruit flies caught in baited traps are analyzed under microscope to make sure they are SIT-reared flies and not unwanted invaders. In Patagonia, Argentina, agricultural engineer Claudia Cartes of FunBaPa - the short name of the fruit industry's quality and safety arm - checks captured flies.  The blacklight confirms the telltale fluorescent dye of a SIT fly. (Credit: FunBaPa)In Argentina, the fruit industry is big business and so is pest control.  Only the best fruit is selected for export at a packing plant in Patagonia.  More than 300 fruit packing plants dot the region, the heartland of the country's apple, pear and deciduous fruit production. (Credit:  Wedekind/IAEA)Esteban Jorge Rial (right), who heads Medfly control for fruit producers in Patagonia, briefs staff and an inspector from the United States Animal and Plant Health Inspection Service (APHIS).  Now tied to the US national security structure, APHIS inspectors oversee fruit and other agricultural exports to the USA.  Trade and quarantines rules are tough, designed to protect the USA's multi-billion dollar fruit and vegetable industry from invasive and destructive pests. (Credit: FunBaPa)The US Animal and Plant Health Inspection Service (APHIS) cleared the Patagonia growing region as "fruit-fly-free" in December 2005. The action recognized the success of efforts to control the Medfly and ended expensive quarantine requirements.  Bigger markets now are open to fruit producers in Patagonia, where poplar-shielded orchards line the Rio Negro oasis.  The region's status means that its fruit, mostly pears, apples, and cherries, can be exported to the USA without quarantine - an annual savings of about $2 million for exporters - and opens trade opportunities in Europe, South America, and other regions. (Credit:  Rial/FunBaPa)Many weapons are needed to fight fruit flies and other agricultural pests. Alongside the SIT technology, vigorous control campaigns target and suppress the Medfly.  In Chile and Argentina, checkpoints are common sights at airports and borders, while agricultural inspectors comb cities and the countryside.  If even one Medfly is detected, the hunt is on.  An emergency is then declared, triggering months-long action by trappers and inspectors to find any more flies that may exist.Chile is officially a "fruit-fly-free" country, but Medflies get into cities through travel and trade from time to time.  In Santiago, the way ahead during an emergency outbreak is mapped by SAG, the national food and livestock authority, whose teams zero in on parts of the city.  High-tech tools, such as a global positioning system (GPS), are as important as pencil, paper, fly traps and expertise in Medfly mating habits to track the Medfly's route. The work is critical: Chile is South America's leading exporter of fresh fruit and vegetables, gaining more than $2 billion a year.  (Credit:  Wedekind/IAEA) When an outbreak hits, teams alert citizens to the emergency and send search squads to inspect targeted neighbourhoods. Each home is checked as part of the hunt, to make sure it's Medfly-free.  In Santiago, Pablo Reyes (centre), SAG's emergency operations leader, goes on patrol with members of his team inspecting a section of the city.  (Credit:  Wedekind/IAEA)As part of operations, experienced eyes and hands seek out fruit that may be Medfly nests. In Santiago, kilos of collected fruit samples are carefully screened, sorted and inspected by local SAG teams.  If Medfly damage or maggots are detected, scientists have the analytical skills and tools to tell where the pest last struck and where it's likely to be heading. (Wedekind/IAEA)SAG's Arica Chief of Operations, Paula Troncoso-Kirsten (centre), and Jaime Gonzalez (second from left), who heads SAG's national fruit fly control programme, join members of the team that keeps the oasis valley in Arica, Chile, free of the Medfly.  They work closely with neighbouring Peru over the hills behind them, which has its own Medfly control programme. (Credit:  Wedekind/IAEA)SAG engineers Tomas Masquimillan-Garcia and Jorge Cubillos Daldo together have more than a half century of experience in agriculture and pest control, mostly in Arica.  They stand among many in Chile who help to win the battle against the Medfly day in and day out. (Credit: Wedekind/IAEA)
Last update: 15 February 2018

Stay in touch