GOOD NEWS: ‘Beetles invasion' captures salt cedar audience

ALPINE Forty eight years ago, the U.S. endured its initial Beatles Invasion — of the musical variety.

Presently, another Beetles Invasion seeks to capture a different audience — the salt cedar.
Researchers at Sul Ross State University are using an imported insect — the salt cedar leaf beetle — to curb the spread of this invasive species.

“The salt cedar is choking out the majority of the waterways in the Southwestern United States,” said Christopher Ritzi, Sul Ross associate professor of Biology. “In Texas in general we have the largest stands of salt cedar anywhere in the country.”

Salt cedar, a native of the Middle East and Turkey, were first imported into the U.S. in the 1800s for erosion control and ornamental (shade) purposes.

“Unfortunately, salt cedar was very good at making itself right at home,” Ritzi said. He noted that salt cedars form “monocultures” by reproducing and choking out other vegetation.

“Salt cedar consume about as much water as a cottonwood or willow, but their stands are far denser, so they use a much higher amount of water in total,” he said.

As salt cedar stands spread, plant diversity declines, attracting fewer animals. When animal diversity drops, “it turns the area into a salt cedar wasteland,” said Ritzi.

Coupled with the recent drought and a hard freeze last winter, the salt cedar leaf beetles have been effective in combating the salt cedar spread.

“Both the larval and adult stages attack the plant,” Ritzi said. “The beetle reproduces very well and is highly host-specific; it only attacks the tamarisk out here.”

The larval and adult beetles attack the salt cedar leaves, causing defoliation. When the shrubs grow more leaves, the beetles resume their attack.

“We are seeing four-five defoliations per year,” Ritzi said. “This consumes the tree’s reserves. With the drought and the freeze, we’re actually seeing some of the plants dying already.

This process usually takes four to five years to see trees dying, but it’s happening in one to two years, which is very promising.”

The only real stumbling block thus far has been that the beetles have also attacked a “sister” tree species used as shade in the area, the athel tree.

He noted that beetles did initially attack the athel trees as well, but seemed to prefer the salt cedar.

“It appeared that the athel was more of a novelty than a primary food source,” he said, and that after the first year of attack, the athels are not being as heavily impacted by the beetles as the targeted salt cedar.

Sul Ross and Rio Grande College, along with fellow campuses in the Texas State University System (TSUS), are at the forefront of program set on early detection and rapid response to invasive species.

The TSUS Institute for the Study of Invasive Species (ISIS) seeks to deal with unwanted plants and creatures via a centralized effort to assess, monitor, contain, and control or kill off species before they extensive damage.

Every entity involved with non-native species at any level will operate with the ISIS in strategic partnerships. The collaborative program will be based at Sam Houston State University, Huntsville.