TAMARISK LEAF BEETLE INVAS

INTO THE COLORADO RIVER ECOS

DOWNSTREAM FROM GLEN CANYO

Larry Stevens

Grand Canyon Wildlands Council
THE TAMARISK CONTROV

Bum Rap: Tama

in lowe

OR: Tamarisk is 

in Grand Can

* ~ 30 neotropi

nest in it in G

* 80‐95% of ~30

nests in Arizo

* It is designate

habitat for e
Tamarisk supports >250 invertebrate he

in the Middle East, but <10 (mostly non‐nativ

Non‐native Manna leafhopper

Opsius stactagalus

Native Sch

s
Biological Contro

Tamarisk leaf beet

(Chrysomelidae: Diorhabda 
• Tamarisk leaf beetles (Diorhabda sp.) from the Middle East are mov

Canyon region from the north

• The beetle was selected as the preferred bio‐control agent for tam

Animal and Plant Health Inspection Service (APHIS) and the Agricultu

(both Dept. of Agriculture), with U. S. Fish and Wildlife Service

• In 1999, after both National Environmental Policy Act (NEPA) and E

(ESA) compliance was completed, the beetles were released into cag

across the Rocky Mountains and Great Plains; however, the beetle w

within 200 miles of SWFL habitat

• The beetle was introduced by private individuals and southern Uta

moving southward towards the Grand Canyon region

• The beetle may eliminate a large portion of the riparian habitat in G

Diorhabda Introduction Backgrou
DIORHABDA LIFE CYCLE

• 300‐500 eggs/female, hatch in 7 days• Larvae live 14‐27 days, 3 instars

• Pupation in a silk cocoon, 7 days

• Adults emerge, secrete pheromones to promote aggregat

female lays eggs on tamarisk foliage every day, livin

•1‐2 generations /yr depending on day length (greater at hi
Only the Fukang (China) and Chlik (Kazakhstan) strains were to be released

believed to only persist in areas above 38° north latitude (approximately a

Lake Powell) due to day‐length requirements and would not be successful 

No releases were to be made within 200 miles of tamarisk areas that supp

southwestern willow flycatcher nesting.The ESA consultation covered the placement of the beetles in field cages, 

of the cages to free the insects to surrounding areas. Coverage for active m

beetles from the experimental release areas was not included.

In 2004, the Delta, Utah, experimental release site was opened for collect

by local agencies in Utah to introduce the beetles to non‐Federal lands. Gr

stocked beetles in at least two sites near Moab in 2004 and another three 

on a larger scale was observed in 2005. Since then, the beetles have move

River almost to the upper end of Lake Powell. In 2006, The City of St. Geor

beetles along the Virgin River at 37° north latitude. By 2008, defoliation al

southwestern willow flycatcher breeding site was documented. The beetledownstream on the Virgin River to at least Littlefield, Arizona, and are exp

Mead in 2009 or 2010. Beetles from Moab down the Colorado River to La

their advance; however, entry into Arizona via Lake Powell/Colorado Rive

FAILED CAVEATS AND CONTAINMEN
“Not Wanted in Arizona: Tamarisk Leaf Beetles “

February 2009
RAPID REDUCTION OF TAMARISK AND UNINTENDED CON

THE SINGLE LARGEST ECO‐IMPACT ON THE COLORADO RIVER SIN

• Increased erosion• Fire hazard• Loss of SWFL and breeding habitat• Loss of other ~ 30 Neotropical migrant birds that breed preferent

• Other wildlife (e.g., reptiles)

• Low tamarisk mortality?

• Rapid selection for resistance to beetles

•Long‐term consequences?
SCIENTIFIC AMERICAN, March 19, 2

Are Beetles Imported into the U.S. to Kill Invasive Trees Do

Strategy that unleashed cedar leaf beetles on Tamarisk tree

revised as the chompers spread to threaten endangered bi

By Anne Minard

SALT CEDAR LEAF BEETLE: Is this little bug being too efficien

BOB RICHARD/US ANIMAL AND PLANT HEALTH INSPECTION 

A foreign beetle imported to attack invasive trees in the U.S

have brought its own culinary agenda. Researchers in Utah a

sounding the alarm about salt cedar leaf beetles, which wer

Kazakhstan several years ago to control invasive tamarisk tre

"Now that the beetle is spreading to large areas, we need to 

unexpected consequences of defoliation and death of the ta

Dennison, a geographer at The University of Utah and lead a

warning of the unintended risks published this month in the 

the journal Remote Sensing of Environment.
Agriculture Department Forced to Re‐examine Tamarisk Lea

Program That Hurts Endangered Songbird

TUCSON, Ariz.— A lawsuit filed by the Center for Biological D

Maricopa Audubon Society on 17 June 2009 has forced the U

Agriculture and its Animal and Plant Health Inspection Servicevaluate their tamarisk leaf‐eating beetle program. APHIS‐re

contributing to the decline of the endangered southwestern 

defoliating the trees in which the flycatchers nest. The re‐eva

modification of the program and to emergency habitat resto

From:http://www.biologicaldiversity.org/news/press_releases/200willow‐flycatcher‐06‐17‐2009.html
WHAT TO DO IN THE 

• Interagency coordination?

• Monitor, esp. habitats, shoreline 

• Active restoration planning for n

vegetation (e.g., GCWC Report)?

• Implementation of restoration ef
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A LARGE AND GROWING BIBLIOGRAP

ON THE RATIONALE AND IMPACTS O

TAMARISK LEAF BEETLE INTRODUCTI