小火蟻入侵茂宜島 新誘餌對付

The first invasion of little fire ants, Wasmannia auropunctata, on Maui appears to have been stopped by the use of an innovative pest control method, according to the Hawaii Department of Agriculture.

The tiny ants, about as long as a penny is thick, deliver painful, long-lasting stings. They were reported by a Maui farmer in October 2009 and were found to infest about a half acre of the farm in Waihee, about 3.6 miles north of the city of Wailuku.

Hawaii Department of Agriculture obtained a special permit from the U.S. Environmental Protection Agency to use an experimental ant bait developed by scientist Cas Vanderwoude with the Pacific Cooperative Studies Unit at the University of Hawaii at Manoa.

The poison, Indoxacarb, is not registered for use against little fire ants on fruit trees, although the EPA has labeled it for other uses.

Ants on the ground can be attacked with poison granules, but not little fire ants on trees. The first step, said Vanderwoude, was to develop a sticky vehicle to spread on the trees. He mixed in a protein-flavored substance to attract the ants to his tree bait and worked to make it suitable for Waihee's wet climate.

Until this new bait was developed, there were only ground treatments for little fire ants. The new bait provided treatment in trees and vegetation where little fire ants nest. The area was treated monthly and by February of 2010, no little fire ants were detected at that site.

But only Thursday did the Hawaii Department of Agriculture feel confident enough to announce success in eradicating the ants.

"We have been routinely monitoring the area and we are confident that the ants have been eradicated on the property," said Dr. Neil Reimer, manager of HDOA's Plant Pest Control Branch. "It's pretty clear that without the development of the experimental bait, we would not have been able to eradicate this pest so quickly, if at all."

Monitoring will continue for at least another year, said Dr. Reimer.

Originally from South America, little fire ants are considered among the world's worst invasive species.Pale orange in color, the tiny ants measure just 1/16th of an inch long.

Little fire ants are a different species from another type of ant found in Hawaii that is also called a fire ant.

"The red ants are also called Solenopsis geminata or the tropical fire ant," explains Vanderwoude, who serves as a state Department of Agriculture researcher on the Big Island. "It can be confusing because both species have a similar common name - fire ants - but they are very different."

Red ants are much larger than little fire ants, measuring about half as long as a penny. They move quickly while little fire ants move slowly.

Red ants are originally from the southern United States and they are most often found living in nests in lawns and other open spaces.

Little fire ants can produce painful stings and large red welts and may cause blindness in pets. They can build up very large colonies on the ground and in trees and other vegetation and completely overrun a property. They will also freely move into homes.

Vanderwoude has launched the Hawaii Little Fire Ant website where visitors can explore and download information on the control, eradication, and biology of this invasive species.

Indoxacarb is designated by the EPA to be a "reduced-risk" pesticide and is considered an organophosphate replacement. It has moderate to low acute and chronic toxicity and does not cause mutagenic, carcinogenic, developmental, or reproductive effects, according to the EPA.

The EPA has approved Indoxacarb as water dispersible granules for use on apples, pears, cabbages, sweet corn, lettuce and fruiting vegetables.