The quarantine of more than 1,200 Christmas trees shipped from the Pacific Northwest is not expected to affect the cost and availability of trees for the rest of the holiday season, retailers and growers said.

That's because the quarantined trees — infected with wasps — represent a small percentage of all the trees brought to Hawai'i.

Matson Navigation Co., the state's main ocean carrier, brings in roughly 150,000 trees each year, company spokesman Jeff Hull said.

Its chief competitor, Horizon Lines, does not disclose figures for Christmas-tree shipments but in general has about 35 percent to 45 percent of the total Hawai'i shipping market, spokesman Ku'uhaku Park said.

State Department of Agriculture inspectors said yesterday that they were holding up four containers of trees. They plan to go through three of the four containers this week, kill the wasps and then release the trees. The fourth container has trees from a different grower, and the state is waiting for instructions from that grower on how to handle it.

Inspectors will shake the trees in a net enclosure to loosen the wasp, whose scientific name is Vespula germanica, or the German yellow jacket, said Janelle Saneishi, a state Department of Agriculture spokeswoman.

The wasp found on the trees is considered a threat because it lives at lower elevations than the yellow-jacket wasp already found in Hawai'i, and it prefers to make nests in homes and businesses, said Neil Reimer, state Department of Agriculture entomologist.

"It is a threat to native species," Reimer said. "The species here now lives at the cooler elevations and can be found in the Volcano area of the Big Island. This one stings and is a predator."

Ralph Nilssen, vice president of Kirk Co., one of two companies whose shipping containers contained wasps, said despite its best efforts, sometimes the wasps slip into containers.

The inspections are part of a statewide effort to keep invasive plants, insects and animals out of Hawai'i's fragile ecosystem, which the U.S. Fish and Wildlife Service says has more endangered species than any other U.S. state. More than 90 percent of Hawai'i's land and freshwater species exist nowhere else.

THE IMPORT TRADITION

Hawai'i's year-round warm weather and humid air does not allow the growth of the popular noble and Douglas fir Christmas trees. So retailers have been shipping them in for more than a century.

This year, the Home Depot store closest to Downtown Honolulu increased its order of Christmas trees to 12,000 — a nearly 15 percent increase — because of anticipated demand, said store manager Kade Kasner.

Home Depot will put its first shipment of nearly 3,000 trees on sale today, Kasner said.

"Last year, we sold out rather quickly and increased our order to anticipate even higher demand this year," Kasner said. "If you reduce the amount of product on the island, you're going to increase demand."

Richard Tajiri, of Christmas Hawai'i, said a phone call is all it takes to get more trees here. He plans to have his Christmas-tree lot at Ala Moana Center up and running by tomorrow.

"If it looks like we're short, I can get more," said Tajiri, who has been selling Christmas trees in Hawai'i for 30 years. "If there's a market for them, we'll bring them in."

Prices of 6- to 7-foot noble firs on O'ahu typically range from about $49.90 at discount retailers up to $99. Six- to 7-foot Douglas firs range from $36.90 to $50.

Aaron O'Brien, of Helemano Farms in Wahiawa, has been trying to sell two varieties of trees that can grow in Hawai'i's climate for the past three years without making a profit.

Helemano Farms grows Leland cypress trees and Norfolk Island pines. O'Brien understands why it's cheaper for retailers and niche Christmas-tree lots to pay shipping costs to import more popular Christmas trees from 2,500 miles away.

"My dad and I started this business, and we're taking a big chance," O'Brien said. "Last year, I sold 1,000 trees, and I've been doubling my business every year. If it doubles again this year, we'll start making money — or at least break even and not lose money."

NO WASPS ARE NATIVE

Wasps are not native to Hawai'i, said Andrew D. Taylor, an associate zoology professor at the University of Hawai'i. One species of yellow-jacket wasp, Vespula pennsylvanica, the western yellow jacket, originally came to the Islands on a Christmas-tree shipment years ago and poses a threat to both native plants and birds, Taylor said.

Even though the wasps freeze in the refrigerated containers, Taylor said, they "re-animate" once they thaw out in Hawai'i's warm climate.

"Now, they're here, and they're a very effective predator," he said. "They could affect pollination of our native, endangered plants. And the insects they eat are the same ones that our native birds eat."

Shaking Christmas trees is the best way to ensure no pests are hidden in the branches, said Bryan Ostlund, executive director of the Pacific Northwest Christmas Tree Association.

Hawai'i and other destinations require shippers of live plant materials to guard against bringing in invasive species. Christmas trees are inspected on farms by Oregon officials and by Hawai'i officials before they get to the retailer.

"It's not uncommon for a pest to slip past," Ostlund said. "Every year there's some kind of pest. It's quite a process."

Just a few weeks ago, Hawai'i agriculture officials took tours of several farms to learn how Christmas-tree growers attempt to remove the pests before shipping, Ostlund said.

"We maintain this program as an industry to show Hawai'i our controls that are in place," Ostlund said. "We do that with every market. We welcome the controls as an industry."

Reach Suzanne Roig at sroig@honoluluadvertiser.com and Dan Nakaso at dnakaso@honoluluadvertiser.com.