WELLINGTON, New Zealand -- It just may spell the end of the world's ugliest headgear: that staple of the Australian tourist shop regular, the cork-fringed hat.
For decades, the inelegant corks dangling from hat brims across the Outback have warded off Australian blowflies, but new research promises a genetic method to keep insect pests at bay.
Two researchers based at the Institute of Molecular BioSciences at New Zealand's Massey University have developed a technique that kills female fruit flies in the laboratory.
Molecular geneticist Max Scott and postdoctoral researcher Jörg Heinrich believe the technique can transfer to other insect species, and in particular the Australian sheep blowfly.
The blowflies are an irritant to humans, but they can be fatal to sheep. The blowflies lay their eggs on the sheep, then the maggots feed on the host.
"It's a major problem," says Lance Wiggins, from WoolPro, the industry group that has funded the Massey research.
The New Zealand work builds on a pest-eradication method called sterile insect technique. U.S. scientists Edward Knipling and Ray Bushland developed the technique of sending sterile male insects out to mate with wild fertile females, ensuring a quick end to the lineage.
This technique has eradicated the screw worm fly from North America, the tsetse fly from Zanzibar, the melon fly from the Okinawa islands, the Queensland fruit fly from Western Australia and the Medfly from Mexico.
Up until now, sterile females have been released at the same time. But Scott says if only male flies are released, the technique is more effective. "You want the odds in your favor," Scott says.
The sterile males are forced to find wild females to mate with; the ensuing lack of offspring speeds the demise of the flies.
The New Zealand research, published this month in science journal Proceedings of the National Academy of Sciences (PNAS), has focused on how to kill off females fruit flies. "The trick is devising a method for separating millions of male flies from female flies," Scott says.
The researchers started with the fruit fly, drosophila. "That's the powerhouse for genetics," Scott says. "It's easy to genetically manipulate."
The scientists have modified the fruit flies so that a protein sensitive to tetracycline, called tTA, turns on a death gene in normal cells. But only the females die, because tTA is made only in female fat tissue. A control element from a female-specific yolk protein gene ensures female-only deaths.
The addition of small amounts of tetracycline to the food inhibits tTA, but if the female flies eat normal fly food (yeast, sugar and cornmeal in an agar mix), the death gene kicks in to kill essential fat cells.
Bingo: millions of dead female fruit flies.
The New Zealand study also found that female flies died only if they were fed a rich diet, containing a high level of yeast. Diet, in addition to tetracycline, could be used to control female viability, Scott believes.
The interest in killing bugs is intense: a British research group has tackled the same problems from a different angle; its work was published in Science earlier this year.
Fruit flies are just the first step for Scott's team. Killing off blowflies in a country that has 46 million sheep is a priority. But the technique could be used to help eradicate many other insects. "We think it will work in a variety of insects," Scott said.