Unwanted: Dead Or Alive
How Invasive Species Could Kill Our Economy
Eric Co emerges from the waters off of the Hilton Hawaiian Village Beach Resort & Spa cradling a large “tumbleweed” of Gracilaria salicornia algae. The seaweed, also known as gorilla ogo, is dark, dense and, from a distance, resembles a large, dirty sponge or a disembodied extraterrestrial brain.
It is as sinister as it looks and, appropriately enough, the result of a failed science experiment.
In the 1970s, gorilla ogo was believed to be a good source of agar, a seaweed extract used as a solidifying agent in everything from ice cream to eye cream, and it was intentionally released in the waters off of Waikiki and Kaneohe Bay as well as off several beaches in Molokai. Researchers were wrong, and the seaweed, a relative of native limu, was left to fend for itself. It did very well.
In the decades that followed, the gorilla ogo has come to dominate Oahu’s south shore, smothering the reefs from Diamond Head to Ala Moana Beach Park, where it makes up 11 percent to 60 percent of the bottom cover. Besides its tumbleweed form, the algae also grow into thick mats, resembling very ugly shag carpeting, which cover large swatches of the reef. Although plentiful, gorilla ogo is largely unknown to most Islanders. That is until a storm or a large swell hits the South Shore and the seaweed blankets its beaches, creating a thick, matted, stinking mess.
“Having a whole bunch of the stuff on your reef really won’t change what the ocean looks like when you wake up to a beautiful Hawaiian sunrise,” says Co, marine program coordinator for the Nature Conservancy. “That is, until you have tons of stinky algae wash up on shore.”
According to Co, a putrid day at the beach is the least worrisome of gorilla algae’s harmful environmental impacts. The seaweed, which doesn’t support or benefit any other marine life, kills coral. While Waikiki’s reefs are hardly renowned for their snorkeling opportunities, they do support an intricate web of marine life. Maybe more importantly, the reefs also protect an already dwindling Waikiki Beach from erosion. The alien seaweed could literally swallow up the world’s most famous beach.
“Coral reefs are very dynamic and complex and support levels upon levels of life. They support our fishing industry, recreation and tourism and our cultural heritage,” says Co. “If we allow this invasive species to grow unchecked, we will have severe economic losses, both in the short term and in the long term.”
Gorilla ogo and a large handful of other alien seaweeds are the latest and quietest of the state’s invasive invaders, which threaten environment, economy and public health. They strike from mauka (toward the mountains) to makai (toward the ocean).
Estimated potential economic impact to Hawaii: $4.6 billion to $8.5 billion
-The Nature Conservancy
Native to South and Central America, Miconia grows to more than 40 feet tall and has broad, purple-colored leaves, which block out the sun to anything below. This Jurassic-era-looking plant is both beautiful and bizarre, which made it a horticulturalist’s delight. It was introduced to a botanical garden in Tahiti in 1937, and quickly spread into the surrounding rain forest. By the 1980s, Miconia, also known as “the green cancer,” had swallowed up 60 percent of the Island’s forest, threatening one-quarter of its indigenous plants and wildlife.
Miconia has a shallow root system, so the trees are easily knocked down by high winds, which leads to devastating cases of erosion. In addition, adult plants can disperse more than 3 million seeds annually. The seeds can lay dormant for as long as three years.
The Miconia was imported into Hawaii in 1960 and soon established itself in the forests near Hana and Wailuku on Maui and west of Hilo and all along the Hamakua Coast on the Big Island. Smaller populations were found in Wailua on Kauai and in Manoa, Nuuanu and Kalihi valleys on Oahu. Miconia is the priority plant pest for Invasive Species Committees on Maui, the Big Island, Kauai and Oahu.
In 1999, University of Hawaii researchers estimated that, if the Koolau Mountains forest, Oahu’s primary source of water, were deforested, the value of the lost recharge to the aquifers would be between $4.6 billion and $8.5 billion.
The threat of invasive species is hardly unique to Hawaii. According to the National Conference of State Legislatures, the total costs attributable to invasive species in the United States amount to approximately $137 billion each year. The cost to U.S. agriculture alone is about $72.7 billion. Overseas, the problem is much the same. In a 1992 study by the U.S. Invasive Species Advisory Committee, worldwide losses to agriculture were estimated at $55 billion to nearly $248 billion annually.
However, Hawaii is unquestionably the hardest hit state in the union. The Islands are home to a third of all the birds and plants on the federal Endangered Species List. Nearly two-thirds of all the plants and birds nationwide that have become extinct once belonged to Hawaii.
Economically, the Islands suffer hundreds of millions of dollars in damages from introduced pests and diseases annually. For instance, an estimated $300 million is lost in potential fruit exports, thanks to the oriental fruit fly and the melon fly. In addition, Islanders annually spend approximately $150 million to control and repair the damage caused by the Formosan ground termite. The Nature Conservancy also estimates that costs associated with potential and present invaders, including the brown tree snake, dengue fever, miconia and the red imported fire ant, could top $180 million a year. Harder to quantify would be the profound lifestyle and economic changes that Islanders and visitors alike would have to endure if these species were to become established.
“The fact that some of the more destructive invasives have yet to establish themselves in Hawaii is largely due to luck,” says Christy Martin, public information officer of the Coordinating Group on Alien Pest Species (CGAPS), an interagency invasive pest working group. “The amount of funding for agricultural inspections has stayed the same or gone down, while the amount of air and sea traffic has increased exponentially. Basically, we’ve been playing a game of Russian roulette, and now we’ve got more bullets in the gun.”
The Price of Being Paradise
The most remote landmass in the world, Hawaii was originally colonized by several hundred species of plants, insects, birds and other organisms that arrived via ocean and air currents. Surrounded by a 2,500-mile-wide moat, this ecofortress was spared the grazers, the predators and the pathogens that were important to the evolution of the continents, and these original immigrants evolved into several thousands of species, more than 90 percent of which are endemic to Hawaii.
The Polynesians intentionally introduced about 30 kinds of plants for cultivation, including the emblematic sugarcane plant and coconut tree. They also brought pigs and chickens as well as stowaways, such as rats, lizards and several insects. The rate of species becoming established in the Islands thus changed from the natural rate of one new species every 50,000 years, to three or four new species every 100 years.
According to a 1994 study by the congressional Office of Technology Assessment, about five new plant species per year became established in Hawaii during the 20th century. For the 50-year period from 1937 to 1987, the Islands received an average of 18 new insects and other species annually-more than a million times the natural rate and almost twice the number absorbed each year by all of North America. This astronomical rate has recently been re-examined after a 2001 pest-risk assessment at Maui’s Kahului Airport (see sidebar below) intercepted an unusually high number of insects. Today, Hawaii may have as many as one new insect arriving each day.
“How bad do things have to get before we tighten things up?” asks Lloyd Loope, research scientist with the U.S. Geological Service, who specializes in invasive species. “When miconia takes over our forests, red imported fire ants have made it impossible for our children to play outside and West Nile virus has killed all the birds? If we don’t do something now, when will we do it?”
Red Imported Fire Ant
Estimated potential economic impact to Hawaii: $15.5 million to $46.1 million
-The Nature Conservancy
One of the few pests that is dangerous in both urban and agricultural settings, as well as in natural habitats, the red imported fire ant (RIFA) seems like a 1950s horror-movie monster. The aggressive ant feeds on fruits, seeds, roots and tubers and damages electrical, irrigation and other mechanical equipment. Inflicting a painful sting, it also attacks animals of all kinds, injuring and killing wildlife, livestock and people.
First introduced into Alabama from Brazil in the late 1920s, the RIFA lay dormant for several decades until the 1950s, when it began to spread throughout the South, sometimes as fast as 100 miles in a year. Today, 11 Southeastern states are infested with the RIFA. In October 1998, California agricultural officials found colonies of RIFA in Orange and Riverside counties. By the size and extent of the infestations, officials estimated that RIFA had been in the area for several years.
While the agricultural damages have been considerable, RIFA has had its greatest impact in the urban setting. In a 1998 study, Texas A&M University researchers found that RIFA damages and control efforts have cost the Texas metropolitan areas $581 million. In a 2000 study, agricultural costs were estimated at $90 million.
In the fall of 2003, financially strapped California announced that it was stopping eradication efforts, which cost the state $40 million. RIFA control and eradication efforts are now the responsibility of the individual counties.
“I don’t have any faith in various counties’ ability to prevent the ants from spreading throughout the rest of the state,” says Christy Martin, public information officer for the Coordinating Group on Alien Species, an interagency invasive pest working group. “It’s no longer a matter of if, but when, RIFA arrives in Hawaii.”
For a little more than a decade, wildlife and conservation officials have been sounding the alarm in a series of increasingly compelling public information campaigns, which warn against the accidental or purposeful importation of such invasive species as the brown tree snake, the red imported fire ant and the biting sand fly, among others. However, while it has elevated the name recognition of several of these species, the campaigns haven’t won the hearts and minds of the general public. The longer the brown tree snake isn’t discovered slithering through a Hawaiian rain forest, the further it slides from the public consciousness.
However, the tide may be changing. Over the past several years, Hawaii has experienced a wave of almost biblical plagues that have sickened, tormented and grossed out Islanders and visitors across the state. In the fall of 2001, an outbreak of dengue fever in rural Nahiku on Maui’s east side paralyzed the Island and put the rest of the state on edge. Since the late 1990s, populations of the vociferous coqui frog (see sidebar on pg. 25) have been keeping bleary-eyed homeowners and visitors on the Big Island, Maui, Oahu and Kauai awake at night. Finally, in the fall of 2002, Salvinia molesta, an aquatic plant widely regarded as the worst invasive weed in the world, engulfed Central Oahu’s Lake Wilson in a blanket of green. It was a graphic and dramatic example of the ferocity of an unchecked invasive species.
Luckily, the latest plagues, while disturbing and newsworthy, are relatively mild in comparison to the misery that potential invaders can bring.
Last summer, Peter Young, chairperson for the state’s Board of Land and Natural Resources, attended a U.S. Coral Task Force meeting in Guam and saw the effect of a real plague. Visiting the island for the first time, Young ditched part of the meeting to tour the Guam International Airport with a U.S. Fish and Wildlife Services official. Young was shown the perimeter fence as well as snake traps, which are stationed 30 to 50 feet apart. That day, Young didn’t see a single snake, which is nocturnal, in one of the traps.
However, that night his guide found a snake for him, very quickly. “I was staying at the Hilton, which was right in an urban area of Guam,” says Young, who had earlier that year led the interagency effort to clean up Lake Wilson. “We walked through the parking lot, across the lawn and into scrub land with haole koa, a landscape that you see all the time in Hawaii. Just walking along that perimeter with a flashlight, we found a snake in 20 minutes.”
According to Young (whose background is in real estate, not biology) it dawned on him then that if he could find a snake, just steps from his hotel, it would be easy for anyone to purposefully or accidentally carry a snake on an airplane.
An economic impact has yet to be estimated
The frog, a native of Puerto Rico, is one of the state’s newest invaders, most likely arriving in a shipment of nursery plants from the island in 1992. However, the recent malahini has quickly made a name for itself. The quarter-size frog has a million-dollar voice, able to blast out a call that ranges from 70 to 90 decibels (about the sound level of a lawnmower).
The Big Island has the largest infestation, with more than 400 populations, followed by Maui. Oahu and Kauai also have naturalized communities. Because they do not have a tadpole stage, and, therefore, don’t need standing water to reproduce, the frogs thrive in a wide spectrum of environments. Coqui populations have been found at sea level and as high as 4,000 feet in Volcano on the Big Island.
While its voice, which deprives residents and tourists of sleep (and is driving down property values), has been garnering most media attention, the frog’s voracious appetite is the main concern for conservationists. In Puerto Rico, the coqui reaches maximum densities of 8,000 animals per acre. In Hawaii, where there are few predators, researchers have documented as many as 10,000 per acre. That many frogs clearing the forest of insects can greatly impact wildlife, especially native birds, which are largely insectivores. In addition, the huge number of frogs will provide an artificial food source for rats and mongoose, elevating their populations. Moreover, the coqui is ideal prey for the brown tree snake.
Hawaii was in serious danger.
“I saw the coqui frogs and spoke to people who were in tears because the noise was deafening,” says Young, a longtime Big Island resident and former deputy managing director for Hawaii County. “I’ve seen fountain grass growing out of control on ranch land, a big fire hazard. I’ve learned that invasive species crosses over many lines. They are environmental, economic and social problems. Fighting invasive species is the Department of Land and Natural Resources’ No. 1 priority.”
In May 2003, Gov. Linda Lingle signed a bill into law that established the Hawaii Invasive Species Council (HISC), a department head-level working group, whose priority is to provide policy-level direction and planning for combating harmful invasive species infestations throughout the state. Besides the DLNR, and the departments of Agriculture, Transportation, Health, the council also includes the heads of the departments of Business Economic Development and Tourism, Commerce and Consumer Affairs, Defense, Hawaiian Home Lands and the University of Hawaii. Also included were the four mayors and various private and federal partners.
In her State of the State speech in January, Lingle named invasive species as one of the five priorities of her administration, and she announced that she would ask for $5 million from the Legislature for the effort. According to Young, the $5 million will be matched by federal and private funds over the course of four years. Thirty-five percent of the money will go to prevention, 30 percent will address response and control, 20 percent will fund research and development and 10 percent will be applied toward new technologies. The remaining 5 percent will go toward education and outreach.
The state’s self-imposed hiring freeze might prevent the officials from bringing on additional agricultural inspectors. But Neil Reimer, manager for the plant quarantine branch of the state Department of Agriculture, says that his staff of 50 inspectors statewide would likely be supplemented by the addition of aides, who would do the manual labor involved in the job, freeing up the inspectors to make examinations.
According to Reimer, inspection-staffing levels have remained static for more than 10 years and have fallen by 10 positions from levels 20 years ago. As a result, inspectors routinely work seven days a week, often a single shift involves clocking in on Friday morning and going home Sunday night. “I’m not sure that our 60 inspectors were even appropriate for the job 20 years ago,” says Reimer. “I do know that we are unable to do certain things that we should be doing. For instance, interisland inspections are not being done to the extent that they should be. As a result, things get spread throughout the Islands, such as coqui frog.”
“We will be dealing with both terrestrial and marine invasive species,” says Young. “The effort will likely call for an increased agricultural inspection capability for the Department of Agriculture. I’m not sure if it will come through the department itself or an expansion of a federal program. However, the result will be the same, inspection capabilities will be improved.”
Besides much needed funding, HISC finally could give the fight against invasive species a little political muscle. Up until now, coordinating the land battle against alien species has been largely the job of a loosely connected network of Invasive Species Committees, made up of middle managers from various state and federal agencies, paid staff and legions of volunteers. The committees target a select list of species for control and are funded by a variety of state, federal and private grants and programs that are renewed annually.
“Even if it happens, I don’t know how effective it will be, but, nevertheless, I’m mildly optimistic,” says Loope, a member of the Maui Invasive Species Committee. “There is so much interest at the grassroots level, but up till now, the highest levels of government have been dismissive. Now things are looking much better.”
Young says that some lessons for the war against invasives can be gleaned from the successful cleanup of Lake Wilson, which involved the coordination of more than 30 different entities and 300 volunteers. However, Young admits that the effort against salvinia, which was conducted in the controlled confines of a man-made, enclosed lake, was relatively easy compared to fighting invasives in the wild.
“I’ll borrow whatever good idea is out there,” says Young. “What we are going to do will be significantly different from the way things are done now. We want to work together, we need to work together and let’s just do it. It’s as simple as that.”
West Nile Virus
Estimated nationwide cost of summer 2003 outbreak: $139 million
-Centers for Disease Control
Extremely virulent and potentially fatal, West Nile virus (WNV) is the most serious public health and economic threat to the Islands in recent memory. The mosquito-borne virus, which primarily affects birds, has been floating around Africa and Europe for thousands of years. However, in the early 1990s, the virus mutated into its more virulent strain and spread quickly throughout Russia, Eastern Europe, North Africa and the Middle East. In 1999, WNV made its way from Israel to New York City. Over the course of a couple of summers, it spread across the country, killing birds, horses and people along the way. According to the Centers for Disease Control (CDC), in 2001, there were 66 cases of WNV in 10 states resulting in nine fatalities. In 2002, WNV activity spread to 44 states, with 4,156 human cases and 284 deaths. In 2003, 7,386 people were diagnosed with WNV, of whom 155 died. CDC officials estimate that the 2003 cases cost an estimated $139 million in hospitalization, doctor’s bills and such things as lost wages, need for extra child-care and transportation.
Colorado was the hardest hit state. The virus, which is not transmitted from person to person, was first detected in the fall of 2002, resulting in just 13 nonfatal human cases. The following summer, WNV swept through the state in just two weeks. On Aug. 18, Colorado health officials estimated that 11,000 people were infected with the virus. By Aug. 30, that number exploded to 35,000. By the summer’s end, 2,745 Coloradoans complained of WNV symptoms, of whom 52 died. Almost all the deceased were elderly. The youngest victim was 53 years old.
Most WNV infected people have no symptoms. About one in 80 infected will develop mild symptoms that include fever, headache, body aches, skin rash and swollen lymph glands. Less than 1 percent of infected people develop more severe illnesses such as meningitis and encephalitis. There is no specific treatment for WNV infection and no vaccine to prevent it.
If WNV were to establish itself in Hawaii’s bird population, the environmental, social and economic costs would likely outstrip those suffered by other infected states. Because it is a mosquito-borne disease, WNV is suppressed during the cold winter months on the Mainland. Hawaii wouldn’t enjoy such a reprieve. Also, because the Islands’ birds are exposed to far fewer diseases than those on the Mainland, WNV would likely be deadlier to the population, and it would probably spread faster than it has on the continent.
“If it gets here and into the bird population, you will not be able to get rid of this,” says Jeff Burgett, invasive species biologist at the U.S. Fish and Wildlife Service. “It won’t die out unless every bird in the state is removed and that’s not going to happen.”
According to Burgett, the virus would be far more difficult to battle than dengue fever, which plagued the Islands several summers ago, because WNV is primarily a bird disease. Dengue, on the other hand, is primarily a monkey disease, which affects humans. Since there are no monkeys in Hawaii, it was relatively easy for local health officials to isolate dengue and wipe it out.
“The strain of dengue wasn’t serious,” says Burgett. “It may have made people feel like they wanted to die, but West Nile can kill you. How many times are you bitten by a mosquito in a week? Can you imagine every one of those instances being a potentially fatal occurrence?”
The 42-Ton Gorilla
Back at the Hilton Hawaiian Village Resort & Spa, The Nature Conservancy’s Co lays down his tumbleweed of gorilla ogo and measures it with a grid made of PVC piping and string. Co is surveying the algae’s population off of the beach to ascertain the effectiveness of a control campaign that started in January of this year. With the cooperation of more than a dozen different public and private partners and hundreds of volunteers, Co and company have removed more than 42 tons of alien algae over the course of three separate efforts.
During the first volunteer alien algae effort at the Hilton, divers carefully removed the gorilla ogo from the reef and snorkelers packed it into burlap bags, which were carried via chain gang from the water’s edge to a waiting dump truck. Hilton officials gave the workers full access to the beach, burlap bags were donated by the Hawaii Coffee Company, Alliance Trucking donated the use of a truck, Teddy’s Bigger Burgers helped out with lunch and the DLNR assisted with permitting. Co anticipated maybe 100 volunteers. He got 200.
“The most amazing thing is that we got a lot of our guests getting in the line and volunteering to help. Some even opened up their wallets and gave money to buy lunch for the volunteers,” says George Hayward, public relations manager for the Hilton Hawaiian Village Resort & Spa. “The environment is important to us. It drives the state and the tourism industry. Our guests realize that, too.”
It’s too early to tell exactly how effective the group’s efforts have been, but an initial examination by divers has found that the population has been significantly reduced. However, more importantly, Co is encouraged by a new awareness in the general public that may be growing as fast as the algae.
“This is a problem that has only just begun to reach the forefront of our awareness. We’re hoping that this effort can serve as an example for the other resorts down the beach,” says Co. “We’ve found that people really want to help. It’s not that they don’t care, it’s that they just don’t know.”
Brown Tree Snake
Estimated potential economic impact to Hawaii: $29 million to $405 million
-The Nature Conservancy
Just mildly venomous and with most specimens measuring between three and four feet long, the brown tree snake pales in comparison to the fearsome serpents seen on most wildlife documentaries. However, the snake’s survivability, reproductive success and voracious appetite are downright scary: One snake made the journey from Guam to Corpus Christi, Texas, inside of a washing machine. The trek took six months and the snake, without food or water, arrived very much alive, and pissed off.
Once on the ground, the snake’s chances of survival are high. Nocturnal and carry-on-size, it is hard to detect. It also isn’t a picky eater, easily adapting to available lizard, bird and mammal prey. In addition, once mated, females can store sperm for years.
The brown tree snake is an animal perfectly engineered for globalization.
Native to the Solomon Islands, Northern Australia and Papua New Guinea, the brown tree snake’s most famous new home is Guam, where it likely arrived via military transports, which were moving men and materiel from the South Pacific following World War II. Several decades later, the snake has single handedly decimated the island’s wildlife, exterminating 12 native bird species, six lizard species and two of three bat species.
While its venom is not a threat to healthy adults, it can cause severe sickness in infants, the elderly and the infirm. A noted climber, the snake is frequently found on power and telephone lines. Since 1978, it has caused more than 1,200 power outages on the island.
At their height in the ’80s, snake densities on Guam reached 40 specimens per acre, some of the highest densities ever recorded. Today, populations are approximately eight to 20 snakes per acre. The drop is attributed to a dwindling food supply. The snake is literally eating itself out of house and home.
The brown tree snake has turned up in Hawaii at least seven times, the latest in 1994, when it was found in a warehouse at Schofield Barracks. It was the first snake captured in three years and the only one that wasn’t found in or around an airplane.
Last February, Guam airport officials found a brown tree snake in a bottle, an apparent attempt to smuggle the reptile off the island. At the time, flights bound for Tokyo and Honolulu were checking in.
High air traffic, low staffing levels and several unique ecological characteristics make Kahului Airport an insect hub
Oahu is the “gathering place” and Molokai is known as the “friendly isle,” but, if you’re a nonnative insect or pathogen, Maui is a combination of both. With 560 monthly flights from the Mainland and an additional 30 from Canada, Maui’s Kahului Airport has become insect central in the state’s war on invasive species.
There are only four state Department of Agriculture inspectors on duty at any one time at Kahului, the same staffing levels the airport had more than 20 years ago, when it didn’t receive Mainland or international flights. As a result, the overworked inspectors put in shifts that would make a first-year medical resident’s head spin.
“Kahului Airport is just one big, leaky sieve,” says Lloyd Loope, research scientist with U.S. Geological Survey, who specializes in invasive species. “Every day new things are coming in. People tend to focus in on the biggest threats, but if a new insect or pathogen is arriving daily, our ecosystem is just being whittled away.”
From September 2000 to July 2001, the Deptartment of Agriculture conducted a pest risk assessment on the movement of alien species into Maui from the continental U.S. and areas abroad. The effort was part of a larger environmental study that was examining the possible impacts of a lengthened runway (and increased overseas air traffic) on the rest of the Island. The department doubled its staffing at Kahului and conducted seven, three- and four-week “blitzes,” which involved intensive inspections of checked and carry-on baggage by inspectors and detector dog teams, inspections of aircraft cabins and cargo holds of Mainland flights and 100 percent inspections of agricultural products shipped by air cargo.
The results made wildlife and conservation officials shake their heads in disbelief. During their blitzes, inspectors intercepted 1,401 insects on agricultural commodities. Of the 279 species intercepted, 125 were not known to occur in Hawaii, 103 were established in Hawaii and 51 were of undetermined status. One hundred fifty-six interceptions involved plant disease organisms, 47 of which were determined to be pathogenic species. A total of 1,404 interceptions was made in the 130-day blitz, a rate that equals the average amount of insect interceptions made statewide.
“What we found wasn’t as eye opening as how much we found,” says Neil Reimer, manager for the Department of Agriculture’s plant quarantine branch. “Essentially, in our business, the harder you look the more you are going to find.”
One of the risk assessment recommendations was to dramatically increase inspection staffing at Kahului Airport to a minimum of 14 inspectors. However, the report pointed out that 19 inspectors was a more “realistic” number, which would account for sick and vacation leave and not require staff to put in overtime. Today, Kahului is still staffed by just five inspectors.
Kahului Airport has more problems than just a shortage of inspection personnel. According to Loope, the airport has a number of environmental characteristics that enhance stowaway insect survivability. “The trade winds blow inland at Kahului, unlike Honolulu International Airport’s breezes, which blow things out to the ocean. An insect could be on top of Haleakala in no time,” says Loope. “Kahului also doesn’t have a separate cargo facility, so aircraft cargo holds are opened up right on the tarmac. And unlike Mainland airports, there are a myriad of microclimates within a short drive of Kahului. Finally, the airport is surrounded by protected wetlands, a perfect way station for insects, especially for hitchhiking, disease-carrying mosquitoes. It’s a nightmare.”
Weeding Out the Pests
A 48-question survey may provide the answer to the Islands’ weed woes
While state, federal and conservation officials are racing to close as many of the back and side doors in Hawaii’s plant quarantine system, many of the Islands’ plant pests are carried right through the front door. According to the U.S. Department of Agriculture’s Forest Service, 60 percent of Hawaii’s problematic plants were intentionally introduced.
The green monster Salvinia molesta, which fouled Lake Wilson two summers ago, is a popular plant used in aquaria. Miconia, the scourge of rain forests in Tahiti, was imported into Hawaii in 1960.
Surprisingly, any plant specimen can be imported into the Islands as long as it is not on the state noxious weed list, a listing that is largely comprised of agricultural pests (specifically threats to sugar cane and pineapple plants) and is infrequently updated.
To be fair, it is difficult to predict which plant will suddenly, without warning, turn into a weed and start dominating a landscape. However, several years ago, University of Hawaii at Manoa botany professor Curt Daehler developed a weed risk assessment (WRA) system that makes pest prediction less of an art and more of a science. Daehler adapted the system from procedures currently in use in Australia and New Zealand.
The WRA is built around a 48-question survey, which covers such areas as the plant’s native climate and environment, and also individual characteristics such as how fast it grows, how quickly it reproduces, if it needs a special pollinator, if it has thorns or if it is toxic. Each question is given a rating, and then a final score is tabulated. If a plant receives a score of zero to five, it is considered safe. If it scores six or higher, the plant is classified as a pest that should not be planted. Salvinia scored a jaw-dropping 28 on the survey, just several points short of pest perfection.
Between December 2001 and June 2002, Daehler scored approximately 200 plants currently in Hawaii against his system. He then sent that list of plants to 25 botanists/weed scientists and asked these experts to rate the plants by their actual behavior. Daehler found that his survey had a 95 percent success rate in predicting pests. Predictions of non-pests had a slightly lower success rate, 85 percent.
“The system is purely voluntary at this point, but we have to start somewhere,” says Daehler. “Our big fear was that our favorite plants and all the money makers would be classified as pests. That certainly wouldn’t be a viable system. We have to balance our economic interests.”
Daehler says that the nursery industry has been receptive to utilizing the WRA. In addition, Peter Young, chairperson of the Board of Land & Natural Resources is currently evaluating the system. But whether or not the WRA becomes government policy, as it has in Australia and New Zealand, Daehler hopes that his findings will be disseminated and will find believers in the grass roots, so to speak.
“Hopefully, the list spreads the word around and people start discussing it and maybe government agencies will look at it and decide to use other, less invasive plants for contract work,” says Daehler. “We are never going to have a perfect system. We can’t say for sure who is right. We just have to make people more aware of the choices that they have out there.”