Bring on the beetles: Monument turns to insects to fight tamarisks

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A Chinese beetle with an appetite for tamarisk may help solve Dinosaur National Monument's invasive weed problem.

Referred to in the science community as the Fu Kang beetle, in reference to its home region in China, the insect is scheduled to be released in Echo Park this spring.

Tamarisk, also known as salt cedar, has plagued the national monument since the 1930s, as it has much of the arid West, said botanist Tamara Naumann.

Tamarisk grows in riparian habitat, or wetlands, absorbing large quantities of water, destroying fish spawning bars, and killing native plant species.

Monument staff already mechanically removes tamarisk with the help of volunteers in the Weed Warrior Program.

This year, 522 volunteers have spent 3,560 hours manually removing tamarisk in campgrounds and research sites.

The monument also uses herbicides to kill tamarisk. But both methods are labor intensive, and herbicides are expensive and pose a risk to the environment, Naumann said.

"With the kind of funding we have now, tamarisk is going to outrun us," the botanist said. "We're making a dent, but we're not going to win the race."

Enter the beetle.

In February the monument applied for a beetle test program, and the state Department of Agriculture selected Echo Park as one of four test sites in Colorado that will try the biological control in the spring.

The beetle eats the leaves of tamarisk, and though it doesn't kill the plant the first time it eats it, successive defoliations eventually kill it.

Naumann provided assurances that the exotic beetle won't eat native plants or crops.

Scientists have been studying the beetle for the past 20 years. Tamarisk is native to Eastern Europe, the Mediterranean and China, and scientists studied beetles that eat the plants in those regions in an attempt to find a strain of the beetle that only eats tamarisk.

"They're finally 20 years into it ready to rock with one bug," Naumann said.

That bug is Diorhabda elongata. It already has been released in Lovelock, Nev., which is on almost the same latitude as Echo Park, and scientists there have experienced excellent results.

But the beetle doesn't eat and kill entire populations of tamarisk.

As the beetle eats, its population will grow, and as the tamarisk population dwindles, so will the beetle population.

"If everything goes well, the target weed will be reduced to the level where it's a normal member of the plant community or at most a nuisance," Naumann said.

Because no native plant species in North America genetically resemble tamarisk, Naumann said it would be highly unlikely for the beetle to begin eating anything other than its target crop.

Tamarisk is a problem along the Yampa and Green Rivers, and Naumann said the beetle population could continue along both river corridors.

Monument staff has met with officials from Moffat and Uintah counties, and commissioners of those counties have approved of the monument's plans, Naumann said.

But she emphasized that no invasive weed management technique was risk free.

"It behooves us to be humble and realize 50 years from now, someone might look back and criticize our decision.

"But I do believe professionally and in my heart that it's the right thing to do," she said.

Rob Gebhart can be reached at 824-7031 or by e-mail at rgebhart@craigdailypress.com.

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