Beetle Release Targets Invasive Tamarisk
The Bureau of Land Management Uncompahgre Field Office (UFO) continues to collaborate with staff from the Colorado Department of Agriculture’s Palisade Insectary after first releasing Diorhabda elongata deserticola Chen, the tamarisk leaf beetle. Riparian sites, selected for release of the tiny beetle with a huge appetite for tamarisk leaves, have long since lost their native vegetation to decades-old growth of tamarisk.
Through the efforts of these two agencies, waterways and riparian areas within the UFO may begin to look much as they did a century ago in just a few years.
BLM’s UFO and the Palisade Insectary have released 34,000 beetles in the last two years, with two releases in last year and a “boost” at one of those sites as well as a new site this year. After the releases in 2007, tamarisk plants in the Bedrock area are now showing some defoliation and staff are working on establishment along the Gunnison River.
“By 2009, we expect to see large-scale defoliation of tamarisk at the release sites,” Insectary Director Dan Bean, who has been involved with leaf beetle research for many years, said. “With Diorhabda, we can be hopeful that waterways and riparian areas throughout the West will once again be prime habitat for native willows and cottonwoods.”
Last year’s release of the beetle only occurred after years of research and interagency cooperation, The Palisade Insectary, operated by the Conservation Services Division of the Colorado Department of Agriculture, plays an important role in the release and monitoring of the insect, which underwent more pre-release testing than any other biological control agent in U.S. history. Experiments with beetle pheromone, the chemical released by beetles when they mate, are being conducted by Insectary staff at some release sites. The release tree is tagged with vials of beetle pheromone and a compound the tamarisk plant releases when it is under attack. The intent is to attract beetles to these trees, keeping them from dispersing.
“The Insectary has taken on a huge workload for the UFO, monitoring these sites and bringing invaluable, in-depth experience to the project,” said Uncompahgre Field Office Manager Barb Sharrow, “It is a great relationship we have going-good for both the Palisade Insectary and the BLM.”
Looking beyond 2008, BLM staff is excited to begin planning for what happens next. Some successful release sites may be used as an Integrated Weed Management experiment. After the tamarisk beetles kill the tamarisk stands through constant defoliation, noxious weeds such as Russian knapweed, purple loosestrife and cheatgrass could invade the area. After effective treatment, the native seed bank should rebound to revegetate the restored areas.
For more information on the UFO tamarisk project, contact Lynae Rogers at 970-240-1068. To learn more about the Palisade Insectary programs, contact Dan Bean at (970) 464-7916.