Introducing the beetles
Helping to save the Walker River Basin with a bug
Tom Dudley, adjunct professor in the Department of Natural Resources and Environmental Science, examns saltcedar leaf beetles at a research site near Lovelock, Nevada.
Photo by Bob Conrad
Tuesday, October 25, 2005
By Jason Ching
North of Hawthorne runs a river of life. The Walker River feeds Walker Lake, a popular fishing destination, and serves the irrigation needs of hundreds of farmers along its course.
But between over-appropriation of water rights, drought and an invasion of foreign trees, water is growing scarce – and everything involved is drying up as a result. That’s why researchers at the University of Nevada, Reno are thrilled with the early successes of a recent biological control program aimed at saving the vanishing waters.
Saltcedar trees, also known as tamarisk, dominate more than 4,000 acres of the Walker River system, an area owned largely by the Walker River Paiute Tribe. From the lower river and the Walker Lake delta to the south shore of Walker Lake at the Hawthorne Army Depot, the non-native saltcedar drains large amounts of much-needed groundwater like thousands of organic siphons.
In addition, it displaces native plants, provides poor wildlife habitat, reduces grazing capacity and increases wildfire, flood and erosion risks. To counteract the destructive trees, in 2001 researchers began releasing the Saltcedar Leaf Beetle (Diorhabda elongata) into the area to remarkable success.
“It’s pretty phenomenal, really,” said Robert Pattison, a post-doctoral researcher with the United States Department of Agriculture Agricultural Research Service. “They’ve spread way beyond what we thought they’d do.”
The beetles, which eat only saltcedar, work by scraping the leaves and stems, causing the foliage to dry out and the tree to eventually die in as little as three years.
This, in turn, has lead to a 75 percent reduction in water loss for the Walker River area in just the first year of defoliation, Pattison said.
Saltcedar affected by the beetles turn brown from the lack of water. Pattison said that while driving for a stretch of about 20 miles, all that could be seen were brown saltcedar.
In response to concerns about controlling the beetles, Pattison said that the beetles will have a very specific effect in the ecosystem.
“We know what they’re going to eat and their impact on other plants is pretty minimal,” he said. “People worry about biological control, but things have come along since the old days.”
Pattison said the concern for the future is preventing weeds such as knapweeds and whitetop from growing in to replace the saltcedar. Eliminating the saltcedar is important, but there’s still more that will need to be figured out, he said.
“[The saltcedar] is a step,” Pattison said. “But we need to be thinking about what happens next, how best to restore the ecosystem.”
Tom Dudley, adjunct Natural Resources and Environmental Science research professor, said that if native plants fill in for all the dead saltcedar, they will still only use half as much water. And in addition to the water loss reductions, wildlife is increasing, specifically native birds that feed on the beetles, and some farmlands that had to stop production may be able to open again.
“I know that a guy up the way is going to be able to open up some land again,” he said. “And he’s going to be tickled pink about that.”