Medfly 'Viagra' may be key to rid pest

By Beverly Creamer
Advertiser Education Writer

In a University of Hawai'i laboratory perched on a Manoa hillside, researcher Todd Shelly is building a better sterile medfly with aromatherapy, using the insect's natural chemical nature to improve its ability to breed in the wild.

Researcher Todd Shelly says the scent of certain natural oils makes sterile male medflies "very competitive in mating." The state gave up the fight to eradicate fruit flies a decade ago, saying it was too costly. Deborah Booker • The Honolulu Advertiser

"If the males are allowed to smell certain natural oils, like ginger root oil, it's like Viagra," said the U.S. Department of Agriculture entomologist and UH associate researcher. "It makes them very competitive in mating."

Unusual? Maybe, but Shelly's work may one day lead to cheaper and more effective sterile fly eradication programs for use worldwide, and here, it is one of a number of hopeful signs that Hawai'i may once again try to eradicate fruit flies, 10 years after it gave up.

Lyle Wong, state Department of Agriculture administrator for the Plant Industry Division, says as much, and is closely watching a five-year melon and medfly suppression program under way on the Big Island and Maui.

If that program has early success in reducing the pests using a combination of the best therapies available — the necessary first step before sterile flies can be widely employed — there may be renewed enthusiasm to pursue financing to eradicate fruit flies throughout the islands, Wong said.

The pests are estimated to cost the state economy $300 million annually because of damage to Hawai'i's fruit and vegetable industry, and eradication could potentially increase exports far beyond their current $500 million a year, experts say.

While California jumps quickly on any whiff of a new fruit fly threat, Hawai'i gave up the fight to eradicate fruit flies a decade ago even though U.S. Department of Agriculture scientists perfected the sterile fly program here and Okinawa used it to rid its own islands of fruit flies.

"They took a technology we developed and applied it very successfully and we haven't, and the questions are why?" said Jim Crisafulli, research and development coordinator for the state Department of Business and Economic Development. "My guess is I think suppression is probably a more realistic goal than out-and-out eradication. That would be a monumental task."

The state has said the cost of eradication was prohibitive. Back then, estimates put the pricetag at half a billion dollars to take out four kinds of fruit flies endemic to the islands — medfly, melon fly, Oriental fruit fly and Malaysian fruit fly. There were also environmental concerns about malathion endangering native insects.

"It was way beyond our capabilities," said Wong, "and probably is today, too."

However, he's keeping the door open and looking hopefully at the progress of the melon fly suppression program as a gauge for the future. Already sterile flies are being released on the Big Island as the populations of wild flies drop thanks to better field sanitation (picking up fallen fruit where flies breed), better bait traps, new environmentally friendly pesticides and the use of natural predators.

Long-time fruit fly researcher Ken Kaneshiro, now head of the Center for Conservation, Research and Training of the Pacific Biomedical Research Center, said the state can and should still try to eradicate the pests, as Okinawa did.

It took a dozen years to wipe out fruit flies on Okinawa's many islands, he said, but as a result the tropical fruit industry has tripled and now they're exporting eradication technology throughout Asia. Okinawa succeeded in eradicating the Oriental fruit fly and the melon fly using technology developed in Hawai'i by the U.S. Department of Agriculture.

That's what Hawai'i should be doing, Kaneshiro said, "because we developed the technology." Okinawa was successful, he said, because they put their best biologists to work understanding the bugs' behavior and habitat, and that's something Hawai'i doing only now.

Shelly's work is exactly what's needed to pep up the factory flies, he said, and someday it will mean cheaper and more effective sterile fly eradication programs.

"This will be a tool worldwide."

California is already paying attention to his research, and so is Stuart Stein, director of the USDA's Hawai'i Fruit Fly Program Facility in Waimanalo. "Anything that makes my 'guys' more competitive is good," Stein said. "When they're pumped up on aromatherapy, it increases their effectiveness and that's impressive."

For 12 years the USDA facility in Waimanalo has been growing sterile flies to keep the medfly at bay in California.

A second Waimanalo facility run by the California State Food and Agriculture Department, is also part of the effort to grow 300 million medfly pupa every week and air-freight them to California. Eventually the USDA factory may also provide flies to Florida, which is now getting the 300 million it needs weekly from Guatemala.

But sterile flies can only be effectively used once the overall fruit fly population is knocked down, Wong said. That's what the Hawai'i suppression campaign is all about — using a variety of techniques and new technology to drop the population.

"You have to knock it down with pesticides and then release sterile insects," said Wong. "If we knocked out fruit flies completely, would there be an incentive for growers to produce fruit and vegetables for export that would justify the cost of doing such a wonderful thing?"

The incentive is clear in California, with a $20 billion fruit, nut and vegetable industry valued at about half of the nation's total, at stake.

While Hawai'i is small potatoes compared with the California industry, Shelly said, the implications of that kind of "wonderful thing" are nonetheless significant, and could lead to major growth.

But Shelly is a scientist with the Animal and Plant Health Inspection Service, and such questions, he said, must be left to politicians. He's far more interested in the production of buff, virile flies eager to meet the ladies.

"The medfly, melon fly and Oriental fruit fly are really affected by airborne smells, like the smells coming out of trees, and things they eat. But how much do you use? You can't dab it (ginger oil) on their ears," he said.

The need is clear, he said, and so is the potential of aromatherapy.

"Once you keep them breeding in a factory for 10 years they become pathetic in terms of mating ability. But if we let them smell the stuff, they get terrific. They kick butt."

Reach Beverly Creamer at bcreamer@honoluluadvertiser.com or 525-8013.

Correction: Okinawa succeeded in eradicating the Oriental fruit fly and the melon fly, not the Medfly, using technology developed in Hawai'i by the U.S. Department of Agriculture. Incorrect information appeared in a previous version of this story.