If efforts to control the little red fire ant on Hawaii stay as they are, the island could see damages of nearly $170 million a year, as well as 33 million sting incidents a year. That’s according to University of Hawaii planning student Mike Motoki, a presenter at the 21st annual Hawaii Conservation Conference held recently in Waikiki.

The bright orangey-red ants – Wasmannia auropunctata — are native to Central and South America and form large colonies on the ground and in trees. In addition to Hawaii, they have also invaded Tahiti, the Galapagos Islands, and other parts of the Pacific. Their burning stings can send you running to the drugstore for a pack of Benadryl.

Using a model insert developed by scientists at UH, Motoki has been able to estimate the potential economic harm and number of sting incidents that are likely to occur with varying levels of ant management. He looked only at impacts to six sectors (nurseries, agriculture, residential, lodging, parks, schools, and other). He did not assess the potential threats to native species or the costs associated with pets blinded by ant stings.

Eradication, he found, wasn’t really worth the cost. His model showed that it would cost about a billion dollars to eradicate the ants from Hawaii island, where they have steadily spread since a state entomologist discovered them there in 1999.

And even if you spent all that money, says Hawaii Ant Lab manager Casper Vanderwoude, “you may or may not succeed.”

The ants, as tiny as crumbs, are notoriously persistent. Eradication is “probably not an economic thing to do” given the cost, Vanderwoude told Environment Hawaii.

Motoki recommended something in between the status quo and total eradication. Spending about $70 million on mitigation and the prevention of an expanded ant range over the next ten years could result in a significant decrease in damages and ant sting incidents, he found.

Currently, the Hawaii Ant Lab, based in Hilo and funded by the U.S. Forest Service, the Department of Land and Natural Resources, and the Department of Agriculture, has an annual budget of only $200,000 to $250,000, Vanderwoude says, and with that he and his staff are supposed to address all ant problems throughout the state. His staff – just 3.6 people – conducts research on better ways to control the LFA and coordinates with the Hawaii Department of Agriculture and island invasive species committees to control incipient infestations and educate the public.

A couple of recent community workshops on the LFA were “frighteningly well-attended,” he says, adding, “The demand for residential workshops has been really, really high.”

The ants have already spread to an estimated 6,000 sites from lower Puna to Laupahoehoe on the east side, and to the Kona airport and Kau on the west. Some 4,000 homes, 186 farms, six parks, a school, a hotel, and 568 other sites on the island have been infested, Motoki said. Fellow presenter Lissa Strohecker, an outreach specialist with the Maui Invasive Species Committee, added that the Hawaii island office of the state Department of Agriculture now gets 25 to 30 calls a week from people seeking advice on how to get rid of the pests.

And the ants aren’t just biting people, they’re hampering inter-island trade and tourism.

Motoki reports that the model predict 23 percent of plant nurseries on Hawaii island are infested with the ant. As a result, a number of landscapers on Maui have stopped importing plants from Hawaii and have started sourcing locally, according to biologist and environmental consultant Forest Starr.

Visitors to a few badly infested beach parks and the Panaewa Zoo are “constantly being stung by ants falling from trees,” according to the ant lab’s website.

Despite the ant’s obvious impacts, Strohecker said, there still seems to be a lack of awareness on Hawaii of how bad the pest can be once it’s established.

“[E]ven though properties have ants, residents are often not treating, or treating too inconsistently to be effective, citing treatment cost and neighboring lot access as limitations,” her abstract states.

Government agencies have been encouraging the landscape industry to treat plants, working with farmers markets to encourage testing, and trying to spread the word at community events with the Big Island Invasive Species Committee, among other things, Strochecker said.

Should resource managers ever get an influx of funds to control the ant, Motoki’s model suggests that focusing on suppression in the agricultural, nursery, and lodging sectors would likely yield more economic benefits than focusing on residential, school, and park sectors. However, that strategy would protect far fewer people from getting stung.

Incipient Infestations

So far, the ants haven’t been detected on Oahu. On a farm in west Maui, a small infestation found in 2009 was thought to be nearly eradicated a couple of years ago, but scientists discovered a nest on the property this year. On a 12-acre site on the North Shore of Kauai, after repeated treatment with pesticides, resource managers are now close to stamping out a decade-old infestation there.

To prevent plants shipped from Hawaii island from causing further infestations, the HDOA requires all potted plants from there to be inspected. If any ants are found, the plants must be treated with pesticide before being shipped. Nurseries inspected twice a year by the HDOA and certified to be ant-free, however, may ship plants freely.

Some scientists and resource managers have recommended tightening the state’s regulations to prevent the transport of any plants from known high-risk areas, but so far, no rule amendments have been proposed.

Presenter Gary Morton of the Department of Agriculture, Fisheries and Forestry in Queensland, Australia, described the protocols and methods his agency has implemented to prevent the spread of the LFA, which was first discovered there in 2006.

In Queensland, where eradication is still possible, 50-meter buffers are imposed around infested areas and landowners are prohibited from moving materials or ants out of the quarantine area without the approval of an inspector, Morton said.

With two trained ant-sniffing dogs (plus their handler), a field staff of five, and strict protocols on moving vegetation, Morton has managed to inspect and treat some 260 hectares.

When inspecting green waste, “that’s where the dogs come in really handy,” Morton said. “They can check some soil and run across some plants very quickly, in a five or ten minute period.”

Morton also advocates for proactively searching for the ants.

“Catching that cycle early, that’s how we’re going to eradicate. There’s less plants that are being moved. Hopefully [we’re] reducing the chance of spreading. … We’re on target for eradication,” he said.

Although penalties for violating the quarantine are high, “we’ve issued warnings but never prosecuted anybody,” he continued, adding that it’s difficult to prove a person knowingly moved infested materials.

Once an infestation is treated with pesticide, his team resurveys the area nine months later with the dogs, then again nine months after that.

“If we find nothing, we declare freedom,” he said.

So how important are the dogs?

For Morton, it means doing only two follow-up surveys rather than three. “They’re also an enormous engagement tool. We’ll do demonstrations at events. They’re such a visible part of our program,” he said.

They are, however, very expensive. His dogs are trained to detect little fire ants – or as they call them in Queensland, “electric ants” – as well as red imported fire ants. The cost of that training: $60,000.

Vanderwoude, who mediated the conference panel on LFA, says the dogs are really handy when eradication is the goal and “where you have to find every last ant.” And they’re also good in a quarantine context. “If you had a trailer load of potted plants … if there was one fire ant in there, they would find it,” he says.

But because they’re so expensive to train and maintain, dogs are not ideal for controlling ants on Hawaii island, “where we have ants everywhere. … You’re not looking to find an ant,” he says. “There is a use for detector dogs, but it’s important to do the math first.”

More information on this problem as well as how to manage Little Fire Ants can be found on the Hawaii Ant Lab website www.littlefireants.com.

About the author: Teresa Dawson is a staff writer for Environment Hawaii and has freelanced for Environmental Health News and the Honolulu Weekly. She was born and raised in Hawaii.


Reprinted with permission from the current issue of Environment Hawaii, a non-profit news publication. The entire issue, as well as more than 20 years of past issues, is available free to Environment Hawaii subscribers at www.environment-hawaii.org. Non-subscribers must pay $10 for a two-day pass.

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