[APWG] Fw: Tamarisk beetles in the news

[Jil_Swearingen at nps.gov]

Subject: USA Today on Invasives



War of the exotic species in the West
By Patrick O'Driscoll, USA TODAY

DENVER - Bug scientists in seven states will unleash swarms of hungry Asian
beetles tonight on a stubborn tree species that is choking life out of the
West's waterways.

Public enemy: Destructive tamarisk, or salt cedar, trees are overtaking
native vegetation along Arizona's Gila River.

Jack Dykinga, USDA

The beetles, no bigger than pencil erasers, should assault tamarisk, also
known as salt cedar. The bushy tree sucks up hundreds of billions of
gallons of water a year and crowds out native plants along creeks and
rivers. It can grow up to a foot a month, to a height of 30 feet. The
leaves secrete salt, making nothing else grow on the ground below.

Tamarisk was imported from Asia in the early 1800s as a garden ornamental
and for windbreaks and other soil-stabilization projects. Its feathery
pink-and white blossoms are common in creek beds and streams in
many semi-arid parts of the West.

Mature trees produce up to 500,000 seeds a year. The species now infests
springs, ditches and wetlands in more than a dozen western states.

It has taken root in more than 1.5 million acres from Mexico to Canada and
from the Midwest to the Pacific.

Spreads easily, hard to kill

Nevada's weed-control office published a poster for the unwelcome tree that
says, "Wanted - Dead, Not Alive!"

For decades, land managers across the West tried to get rid of tamarisk by
cutting, burning, bulldozing and spraying it with herbicides. Their efforts
- costing up to $3,000 an acre - yielded poor to mixed results.

All those seeds spread easily, sprouting wherever the soil is moist.

As agricultural scientists began to have success using insects to battle
certain weeds and other insects harmful to crops, they looked for the
tamarisk's natural predators.

                THE TAMARISK LEAF BEETLE
 <http://www.usatoday.com/_photos/2005/08/02/beetle-notch.jpg>

Scientific name: Diorhabda elongata
Origin: Central Asia
Length: 0.2 inches
Width: 0.1 inch
Coloring: Bright yellow with black stripes
Life span: An adult lives about 18 days
Eating habits: Energetic feeding on the tree throughout its life
Source: USDA Agricultural Research Service

That led to the tamarisk leaf beetle, Diorhabda elongata. The insect,
native to the same Asian regions where salt cedar comes from, is a
voracious feeder that strips the tree of its leaves.

Without leaves, there is no growth and no seeds to propagate.

Best of all, the beetles eat nothing else. While they were tested under
quarantine, they "were fed all kinds of things, from broccoli and tomatoes
to redwoods and more native plants. They don't go for anything else but
tamarisk," says Dan Bean, a beetle scientist in Colorado.

Releasing the beetles this month culminates two decades of work that began
at the U.S. Agriculture Department's research lab in Temple, Texas, a state
where tamarisk is rampant, especially along the Rio Grande. Lab scientist
Jack DeLoach and others made early contacts with entomologists in China,
Kazakhstan and Europe. The first beetle
specimens were brought to the USA in the early 1990s for lab testing. The
experiments gradually moved outdoors.

In 2001, scientists released 1,300 beetles in former alfalfa fields in
Nevada that had been overrun by tamarisk. Within two years, 400 acres of
the invasive trees were stripped bare. That became the place to gather
thousands of beetles that are now being released.

"I wouldn't say that we have the upper hand on (tamarisk), but we're
certainly moving in that direction pretty fast. This is the real thing
now," says Bean, who runs the Colorado Department of Agriculture's
"insectary," an indoor breeding center for beneficial bugs.

On Monday, Bean's group shipped, by Federal Express, dozens of tubular
cartons containing about 45,000 tamarisk leaf beetles. They are due to
arrive today at 24 release sites in Colorado, Idaho, Kansas, Montana,
Oregon, South Dakota and Wyoming.

This evening, scientists at each site will carry the refrigerated
containers to a single tamarisk, previously flagged with a red streamer.

Keeping the bugs chilled and setting them out in the evening should keep
them from flying in all directions. The idea is to spend the night feeding
on the host tree, then begin to mate and lay eggs the next day on its
branches. Only then, the scientists hope, will the beetles begin to fly off
and infest surrounding tamarisk.

Some earlier tests at a dozen sites in California, Colorado, Montana,
Nevada, Texas and Wyoming didn't work because of climate and daylight
patterns different from the beetles' native habitat. Researchers are
studying other strains of the beetle for release in the Southwest, where
the tamarisk problem may be the worst.

Andrew Norton, a bug scientist from Colorado State University who will
release beetles along the South Platte River north of here this evening,
says the species has undergone more testing than any other bug in U.S.
history for controlling plant invaders.

Tamarisk's natural enemy

Norton says many of the millions of species of beetles in the world "are
very specific about what they eat. That's why biological control can work.
It's possible to introduce a specific species that will feed strictly on
(tamarisk) and not on any desirable vegetation."

As many as a dozen new insects arrive unintentionally each year, often as
stowaways in cargo from abroad. Some, like a strain of Asian ambrosia
beetle found in April near Boston, are believed benign. Others, like the
emerald ash borer from China, are enormously destructive. That pest has
infested or destroyed more than 8 million ash trees in Michigan, Ohio and
Indiana since it was found near Detroit in 2002.

If successful, the beetle assault will take years to stop the spread of
tamarisk, let alone allow native plants to re-establish. Thomas Stohlgren,
a U.S. Geological Survey scientist who is mapping the spread of tamarisk,
says the tree is moving beyond river zones to small agricultural ditches
and even desert springs, "any place it can tap into
the water supply."