Agricultural scientists around the world will have their eyes on Hawaii next year as the state Department of Agriculture prepares to release a non-native moth in an attempt to battle an invasive plant that poses a great threat to the ranching industry.

Hawaii scientists will be the first to test out the Madagascan fireweed moth, Secusio extensa, as a biological population control method against fireweed, or ragwort.

The pasture-damaging weed, thought to have traveled here in mulch imported from Australia in the early 1980s, also is wreaking havoc on land and livestock in Australia, Japan, Brazil and other South American countries.

The state approved the release of the moth in 2010 after years of research determined that it would not be a threat to existing species or disrupt the ecosystem, but it took the U.S. Department of Agriculture until Dec. 6 of this year to issue a federal permit for the project.

Since then, scientists have stepped up laboratory production of the moth, and it is expected to be released sometime early next year.

"There are people that are going to have issues with biocontrol because it’s introducing something that’s not from here," said Darcy Oishi, section chief of the state DOA’s biocontrol section. "But it comes down to (having) three viable options. Right now, one is to do nothing; the other is to continue doing chemical control — and those two options basically mean that ranching comes to an end in Hawaii — and there’s biocontrol."

State entomologists and researchers have been searching for a natural remedy to control fireweed — now estimated to have infested more than 850,000 acres, mainly on Maui and Hawaii island — since 1999, when it became apparent that the plant could no longer effectively be treated with herbicides or other removal methods.

"When the population is small, chemicals work really well," Oishi said. "But when you’re talking about hundreds of acres, or thousands of acres in most cases, that is not (economically) sustainable."

The spread of the weed threatens Hawaii’s ranching industry because it poisons livestock and in certain areas has reduced cattle feed production by as much as 60 percent, said Mark Thorne, state range specialist with the University of Hawaii’s College of Tropical Agriculture and Human Resources. It has also grown more aggressively during the state’s current extended period of drought.

The Agriculture Department said it has been looking for a way to effectively control fireweed for more than a decade. Scientists traveled to Australia, South Africa and Madagascar in 1999 and returned with 14 insects and one fungus that were tested under quarantine and found to be ineffective, or harmful to native or beneficial plants.

Trips were made again in 2005, 2007, 2011 and 2012 to search for more solutions. The moth has been the most promising.

The state said it has released 51 biocontrol agents since 1975, all of which have been successful and found not to attack anything but the targeted pest or weed.

"Years of extensive research have been conducted on this biocontrol program," said Russell Koku­bun, chairman of the Hawaii Board of Agriculture. "Control of this weed is one of the more important issues to Hawaii ranchers, and we are hopeful that it can be controlled by this natural process."

Oishi said the larvae of the moth that will soon be introduced in Hawaii feeds on the leaves of the weed, but reducing fireweed back to a manageable level will require the introduction of additional natural plant enemies or diseases and could take 10 to 15 years.

"It’s best if we could find something to attack every part of the plant," he said, adding that the DOA is testing four insects that feed on other parts of the weed.

Oishi said reducing the weed’s population alone won’t turn around the state’s embattled agriculture industry, but it will help.

"It’s not just fireweed," he said. "It’s the drought; it’s getting feed from the mainland, land issues. There’s a whole set of problems that the ranchers are facing that will impact the long-term future of ranching in Hawaii, but if we don’t do something to address fireweed, then it essentially guarantees that the ranchers are not going to remain profitable for very much longer."