Brazilian insect could slow growth of nonnative strawberry guava tree
POSTED: 1:30 a.m. HST, Jun 23, 2010
LAST UPDATED: 2:36 a.m. HST, Jun 23, 2010
The state is once again seeking approval to release a Brazilian scale insect into Hawaii forests to control the spread of the popular but environmentally needy strawberry guava tree.
The state Department of Agriculture is expected to release an environmental assessment today, and the public will have 30 days to weigh in on the controversial bio-control initiative, which has been hotly debated for the past two years.
The assessment notes that the nonnative strawberry guava, which does not have a natural predator in Hawaii, crowds out native plants and animals and reduces the amount of water in soil, streams and groundwater systems by as much as 50 percent during dry periods. According to information cited in the study, strawberry guava also threatens Hawaiian archaeological sites and supports the proliferation of fruit flies, which can damage commercial produce.
"At its current trajectory, strawberry guava will take over all native plants statewide unless something is done," said Christy Martin, public information officer for the Coordinating Group on Alien Pest Species, which coordinates alien pest responses by the state departments of Agriculture, Health, Land and Natural Resources and other agencies.
A previous environmental assessment was released two years ago but was withdrawn, Martin said, because it did not include a cultural assessment. At the time, the proposed initiative drew sharp criticism from those who argued that the plant was an important source of wood and food, and those who warned that introducing the nonnative insect, Tectococcus ovatus, could have unintended negative impacts on native plants and animals.
In August 2008, the Hawaii County Council adopted a nonbinding resolution, introduced by Council member Kelly Greenwell, calling for a ban on bio-control of plants and trees related to the ohia lehua, including strawberry guava.
According to the Coordinating Group on Alien Pest Species, alternatives like physically removing the plants or spraying them with chemicals are "limited and unable to address the magnitude of the problem and the rate of spread."
The Brazilian scale insect feeds exclusively on two kinds of strawberry guava, including the one found in Hawaii (Psidium cattleianum). According to the U.S. Forestry Service, the insect has not shown any tendency to feed on other forest plants, even those related to strawberry guava. The assessment notes that independent studies support its contention that the insect's introduction will help to control the spread of strawberry guava without harming other native or nonnative plants.
According to Martin, the insect will weaken the plant and slow its rate of growth, but will not necessarily reduce the current number of plants in Hawaiian forests, allowing native plants a better chance to survive.
Big Island resident Sydney Singer has been one of the most outspoken opponents of the state's efforts to control or eradicate so-called alien pests. He and his wife, Soma, operate a 60-acre coqui frog sanctuary, and Singer is also involved in litigation over the attempted eradication of mangroves on the Big Island.
Singer said he was "shocked" that the proposal is moving forward despite community objections.
"I thought we got through to them," he said. "It's a big corruption. They control what belongs and what doesn't belong, and even if you speak out against it, they don't care. They'll unleash biological warfare. This is biological destruction."
Singer, who calls the research cited by Coordinating Group on Alien Pest Species "bogus," said he fears the insect will eventually adapt to declining strawberry guava numbers by preying on other native and nonnative plants. He also objects to what he sees as government incursion on his chosen way of life.
Singer, who came to Hawaii from New York 18 years ago, said he lives a self-sufficient, sustainable lifestyle that includes eating wild food like strawberry guava.
"Bio-control is not area specific," he said. "If you own property that has strawberry guava, like I do, (the insect) will damage your trees. I enjoy the fruit and I enjoy the wood, and they have no right, just because they decide it's an alien pest, to wipe it out on everyone's property. This is completely inappropriate to a culture that honors property rights."
Singer said that whatever control needs to be exerted to control the plant should be carried out by hand.
However, Art Medeiros, a research biologist with the U.S. Geological Survey who specializes in restoring Hawaiian ecosystems, says manual removal of a species as widespread as strawberry guava would be like "bailing the ocean."
Medeiros said the strawberry guava situation is similar to what he saw while trying to clear invasive clidemia on Molokai 30 years ago.
"The first year, we pulled out 150 plants, and we high-fived each other because we thought we had stopped it," he said. "Then we came back a year later and pulled out 1,500. After that, we gave up because it had completely overrun the forest."
Medeiros said he understands and respects people who object to bio-control as a means of controlling strawberry guava. However, despite his own initial skepticism, he says he is convinced that releasing the scale insect is the only feasible way to keep the strawberry guava from overrunning native forests.
Acres already densely infested
Acres of native forest areas that could become densely infested at current rates of growth
Acres of native forest not yet threatened
"I've been to Brazil, and I've seen the way it overwhelms forests," he said. "I wouldn't be supportive of this if there was even a one-in-a-million chance of physically controlling (strawberry guava). But there's not. It's winning out over the ohia lehua and koa because there's not enough room for everybody, and it has such an advantage because it has no natural predators here."
To Medeiros, the threat is real and the solution is a "no-brainer."
"The house is on fire, and we're arguing about whether the carpets are going to get wet," he said. "I'm Hawaiian, I'm local, I've spent a good 15 years in the rain forest. If there was another thing we could do, we would. But our backs are against the wall, and this is the best carefully tested option we can envision. If we don't do this, our future generations may ask why we didn't do something when we had the chance."
Lance LaPierre, a native Hawaiian cultural practitioner and educator, agrees.
"We're losing our native species and with that we lose our stories and our culture," he said.
"Take a hike and see how many species there are living around strawberry guava," he said. "There aren't many because they can't. It's choking our native forest, and the forest can't fight back. It tries but it can't. Somebody brought (strawberry guava) here. Now we have to step in, say 'we're sorry we hurt you,' and do what we can to aggressively stop it."
ON THE ISLANDSConsidered one of Hawaii's most destructive invasive species, strawberry guava is commonly found on all major Hawaiian Islands. Potential and current areas of infestation of strawberry guava :
ON A BUG HUNTThe state Department of Agriculture is expected to release today an environmental assessment calling for the use of the Brazilian scale insect to combat strawberry guava growth.
GROWING PROBLEMNative to southeastern Brazil, strawberry guava:
» Does not have a natural predator in Hawaii.
» Destroys habitats for native insects, animals and plants.
» Threatens Hawaiian archaeological sites.
» Supports the proliferation of fruit flies, which can damage commercial produce.
CONTROVERSIAL SOLUTIONThe Brazilian Tectococcus ovatus insect:
» Feeds exclusively of two types of strawberry guava, including the one found here.
» Settles and feeds on newly sprouted strawberry guava leaves, causing the leaves to form growths called galls. Galls divert energy that would have been used for growth and fruit production.