Alien wasp may doom the wiliwili

By VALERIE MONSON, Staff Writer

KAHULUI – An alien wasp discovered on Maui only a week ago has been spreading like an explosion of confetti and could spell doom for the cherished wiliwili trees.

“This is going to be a daunting task if everyone is not willing to work together,” said state entomologist Mach Fukada as he examined a grove of infested trees at Maui Community College on Friday. “This is a whole new ball of wax. It’s not like we can pull a book off of a shelf that tells us what to do. We’re in uncharted waters.”

The culprit is the erythrina gall wasp, an insect not much bigger than a speck that lays its eggs in the leaves and stems of the various kinds of wiliwili – the elegant native Hawaiian trees as well as the non-native species that are often called tiger’s claw or coral trees. As the wasp larvae grow in the plant tissue, they induce an outbreak of tumors (galls) on the leaves and young shoots, making them look like they have smallpox.

The prognosis is grim.

“Literature suggests that it can kill the trees,” said Fukada.

Worse yet, because the diseased leaves often fall off, they can scatter with the wind and easily blow down the street to another property, drop into the back of a pickup driving to Hana or fall into a crate bound for another island. After pupation, the adult wasps bore holes through the galls and emerge to eventually lay more eggs wherever they can find a new wiliwili.

“It’s pretty scary,” said arborist Ernest Rezents. “They’re moving so quickly. If we don’t do something, we’re going to lose a lot of these trees.”

In less than seven days beginning July 30, Fukada detected gall-infested trees at shopping centers in Kahului and Kihei, at Maui High School, near Maui Community Correctional Center and in Maalaea.

“The more I look, the more I’m finding,” he said.

Because of the gravity of the situation, a meeting with Mayor Alan Arakawa was held Friday morning where research biologist Art Medeiros pulled together many of the island’s specialists in alien species control. After a 90-minute strategy session, the county agreed to contribute up to $100,000 that was earmarked in the current budget as an emergency reserve fund to attack invasive species that threatened the island.

“The money was targeted for just this sort of thing, to be able to respond to an unnamed species,” said Rob Parsons, Arakawa’s executive assistant for environmental concerns. “So here it is a month into the new fiscal year and we’re looking at possibly spending the whole thing.”

The Maui Invasive Species Committee (MISC) was appointed as the coordinating agency for the effort that will involve pruning and destroying the contaminated leaves and stems through composting under heavy plastic. The agency issued a press release urging anyone who notices a tree with the disease to call 573-6472 or e-mail digital images to miscpr@hawaii.edu. (The wasps are not a threat to human health.)

The erythrina gall wasp was not even known until a year ago when it was described as a new species in Singapore and on two islands in the Indian Ocean east of Madagascar. Later in 2004, it was found infecting the coral trees of Taiwan and, this past April, it was reported in Manoa on Oahu. In just four months since that initial sighting, the wasp – which Medeiros describes as “the size of a comma” – has spread across the entire island, stunning experts with its shocking speed.

Hopes that the pest could be confined to Oahu were dashed when, less than two weeks ago, wiliwili galls were spotted on the Big Island, Kauai and, finally, Maui. There’s been a preliminary report of the disease on Molokai, too.

“We’re on the edge of something that I’ve never seen before,” said Medeiros. “This is like miconia except it’s so much faster and so much more destructive. I’ve heard of invasive species all my life, but this is the most dramatic and devastating I’ve been around.”

Medeiros was especially crushed because of the possible effects at Puu-o-kali, a rare native Hawaiian ecosystem on an old cinder cone on the southern flank of Haleakala that contains the last intact native wiliwili forest in Hawaii, meaning it’s probably the last in the world. For several years, Medeiros and a dedicated group of volunteers have been fencing and restoring the 236-acre enclosure.

When he was at Puu-o-kali two weeks ago, Medeiros said there was no sign of the wasp. Now, he’s praying.

“If I see it in the mountains, it will be too late,” he said. “If we lose the coral trees (the non-native wiliwili), we can get more of those from other parts of the world, but if we lose the (native) wiliwili, we lose them forever.”

When the native wiliwili are in bloom, they produce one of the most spectacular scenes in nature with fat blossoms in a kaleidoscope of colors and porcelainlike bark that seems to glow from within. Traditionally, the lightweight and buoyant wood turned into canoe outriggers, fishing gear containers, net floats and long surfboards, according to Tina Barnes of the Maui Nui Botanical Gardens. The soft wood was also prized for carving and would occasionally take the place of whale ivory in the making of lei palaoa where the carved object, often in the shape of a fishhook, was suspended from finely braided human hair.

The seeds and flowers of the wiliwili are still commonly used for lei.

Fukada said the value of the trees goes beyond monetary terms.

“You can’t put a price on cultural resources,” he noted.

Rezents worries that if the wiliwili suddenly disappear, there will be consequences for the many endemic insect species and birds the trees help to support.

“The whole ecosystem will be impacted,” he said.

There are probably between 10,000 and 20,000 native wiliwili on Maui, many of them visible on the drive from Ulupalakua to Kaupo.

The different types of non-native coral trees have long been popular, too, either as landscape plants because of their showy red blooms or as windbreaks, such as the ones that line Mokulele Highway (which remain disease-free).

Fukada happened upon the wasp damage by accident. He had gone to a shopping center for a lunch of Korean food with his wife. When she wanted to browse the stores, he decided to examine some nearby wiliwili trees since he was aware of what was occurring on Oahu. He was horrified to find them already awash with galls.

“What I think probably happened was that an infested leaf got transported here from Oahu,” speculated Fukada. “It could have fallen into a container with construction materials or come over (on a barge) in someone’s car.”

The coral trees at Kahului Airport have not yet been impacted. Fukada thinks because the airport is one of the windiest parts of the island, the tiny wasps might not survive as well in that environment.

But they’re flourishing with gusto at the pretty MCC campus that Fukada calls “ground zero.”

College representatives were on hand for the meeting with Arakawa and were fully prepared to cooperate.

“We’re taking the lead from the county and assisting them in every way to take care of this wasp,” said Robert Burton, physical plant manager at MCC who’s responsible for maintenance of the buildings and grounds. “We want to see the trees preserved so we’re providing an example and we’ll see how it goes.”

Burton said he’s informing his staff “so they won’t be surprised when the arborists come in.”

Plans call for pruning the wiliwili on campus – there are both the upright, windbreak type of non-native tree and the more graceful non-natives with the canopy. All infected plant materials will be chipped on-site and composted by placing them in a field and covering them with heavy black plastic to cook in the sun where any pests under the tarp should be killed.

“Then we’ll try to keep the remaining plants as healthy as possible and continue to monitor them,” said Burton.

Medeiros and Fukada believe that biocontrol will be the only long-term salvation for the survival of the trees. Because the wasps appear to attack nothing outside of the erythrina family, it’s hoped that a parasite can be found to prey upon it without harm to other species. Unfortunately, the earliest a biocontrol agent could be approved and available would be six to 10 years.

“The feeling is we don’t have six to 10 years to wait,” said Fukada. “Hopefully, what we can do is buy some time until we can get biocontrol. Right now, we need to slow it down so there’s a chance.”

Already, Medeiros is talking about gathering seeds of the native wiliwili to be stored in case the current population gets completely wiped out.

No one knows how the wasp got to Hawaii.

Parsons said that fact alone points out the critical need for intensive inspections of incoming cargo to Hawaii at airports and harbors that would be implemented if Congress passes a bill introduced 10 days ago by U.S. Rep. Ed Case.

In the meantime, a systemic pesticide might be used, said Fukada. Whatever method is employed, cooperation from the community will be the key to saving the trees.

“We’re not looking at trying to chop people’s trees to the ground,” said Fukada. “People wouldn’t go for that. But we’ve got to have a local control effort to knock things back.”

The gall wasp follows on the heels of fireweed, the hala scale, kahili ginger, Christmas berry, the coqui frog and miconia as major threats to the native Hawaiian landscape.

There’s more. A new ohia “rust” – found on plants in two Maui nurseries – could wreak even more havoc than the gall wasp because it attacks a variety of trees, said Fukada. Although the infected plants were confiscated and destroyed, no one knows if others were sold.

Other heavyweight pests are hovering on the horizon: mosquitoes that carry West Nile virus, red fire ants, nettle caterpillars and brown tree snakes.

“We know this isn’t the last time this will happen,” said Fukada, alongside a wiliwili impacted by galls. “It’s gotten so easy to travel and it’s gotten so easy to send things between the islands, it’s probably only going to get worse.”

Valerie Monson can be reached at vmonson@mauinews.com.