The risk in beetle vs. tamarisk


Margaret Coulombe

The Seattle Times reported June 22 that the United States Department of Agriculture (USDA) had halted the release of the saltcedar leaf beetle, Diorhahda spp., as a biological control agent for the tamarisk (saltcedar) that has invaded riparian habitats in the West.

Concerns about the uncontrolled spread of the beetle and an endangered species of bird, the willow flycatcher, caused the “cease-fire.” The flycatcher has been found to nest in stands of tamarisk that have replaced native willows and cottonwoods.

ASU scientist Matthew Chew told Associated Press reporter Mead Gruver that “saltcedar has been successful in part because of the dams built in the West during the 20th century...and that the dams altered the natural flow of Western rivers like the Colorado, giving saltcedar trees an advantage over native willows and cottonwoods.”

Chew points out that the tamarisk (introduced during the 1930s) “...adapted to this new regime - this new, artificially managed regime. We created a habitat. We created the perfect conditions."

The Times article reports that environmental groups, the Center for Biological Diversity, in Tucson, Arizona, and the Maricopa Audubon Society, sued to halt release of saltcedar leaf beetles in southern Utah in 2006. “The released beetles proliferated, destroying several saltcedar trees containing southwestern willow flycatcher nests,” the groups said.

Chew also noted, in a separate news report issued by CBS News, that the “program to use leaf beetles to combat tamarisk was instituted in 2005, without the USDA completing a detailed environmental review that consider the impact on the bird population.”

Chew, an assistant research professor with Center for Biology and Society and the School of Life Sciences in the College of Liberal Arts and Sciences, researches the history of ideas about ecological integrity and nativeness, and the ways scientists' conceptions of belonging together and belonging in place influence public opinion and inform resource management laws and policies. Chew is the author of “The Monstering of Tamarisk: How scientist made a plant into a problem” in the Journal of the History of Biology and coauthor of “Changing Perceptions of Change: The role of Scientists in Tamarix and River Management” in the journal Restoration Ecology (2009).