Imports to Double-Team a Spiny Weed
By Jim De
TEMPLE, Texas, March 19--One thousand tiny flea beetles from Italy
could be released in the United States for the first time this month, leading
off the latest round of Agriculture Department scientists battle against
musk thistle, a spiny pest in 32 states.
We hope this flea beetle will complement three other insects
weve imported, tested and released to attack musk thistle, said
entomologist Paul Boldt with USDAs
Agricultural Research Service here. The
weed has taken over millions of acres of range, pasture, cropland, parks,
roadsides and other areas in 32 states, he added.
About the end of March, Boldt plans to release Psylliodes chalcomera
flea beetles at a test site near Comfort, Texas, about 40 miles northwest of
San Antonio. They would join the Cheilosia corydon syrphid fly, another
Italian insect first freed there in 1994. We may learn this spring
whether Cheilosia has made itself a permanent new home in this
country, said Boldt, with ARS Grassland, Soil and Water Laboratory.
Psylliodes flea beetles are also scheduled to be released this year
at sites near DeSoto, Kan., and near Hagerstown, Md., Boldt said.
In tests in Italy, ARS entomologist Gaetano Campobasso and colleagues
determined that the Psylliodes and Cheilosia insects will not
harm U.S. native or crop plants including artichoke and chicory, two of musk
ARS earlier obtained a permit to import both insects and to release
Cheilosia from USDAs Animal
and Plant Health Inspection Service. Boldt will release Psylliodes
flea beetles pending a final approval from APHIS. APHIS has made available an
environmental assessment stating that releasing the beetles would have no
significant adverse impact on the environment.
Campobasso collected Psylliodes and Cheilosia insects in
southern Italy in early March and shipped the insects to Boldt. Campobasso
works at the Rome substation of ARS European Biological Control Laboratory.
The lab, based in Montpellier, France, is USDAs primary European source
of insects and microorganisms with potential as natural alternatives to
An article about the two scientists musk-thistle biocontrol research
appears in the March issue of the agencys Agricultural Research magazine
(in press). Musk thistle, or Carduus nutans, originated in Europe and
entered the United States 150 years ago. It grows about 6 feet tall, chokes out
forage plants on range and pasture and displaces other desirable plants. Spines
on the branches, leaves and flower heads ward off most animals, and cattle
wont graze near the weed.
Boldt said the spines also pose a pin-pricking hazard for unwary hikers who
brush past the weed. Its tough to stop, he said in the
magazine article. On rangeland, the benefit from herbicides isnt
worth the expense. And they cant be used near areas such as beaches and
Boldt and Campobasso said biological control is the best long-term strategy.
Theyve investigated a variety of thistle-loving insects since the 1970's.
Two weevils that they and colleagues imported earlier are helping control the
weed in several states. We need a diverse team of insects to attack
different parts of the plant at different times of year and in different
climates, Boldt said.
Larvae of the Cheilosia syrphid fly feed in the crown or rosette of
young musk thistle plants, and on large flower-bearing stems. Immature
Psylliodes flea beetles feed on the rosette and on leaf and flower buds.
Adult flea beetles feed on the leaves.
ARS scientists are working closely with entomologist
of Kansas State University,
Manhattan, to coordinate U.S. distribution of Psylliodes for the
releases in Kansas and Maryland in 1997 and in about 20 other states in 1998.
Scientific contact: Paul Boldt, entomologist, Grassland, Soil and
Water Laboratory, Agricultural Research Service, USDA, Temple TX 76502, phone
(817) 770-6530, e-mail email@example.com; and Gaetano
Campobasso, entomologist, Rome, Italy, substation of the European Biological
Control Laboratory, USDA-ARS, Montpellier, France, phone 011-39-620-609-346,
At APHIS, contact H. Nolan Lemon, Jr., Riverdale, Md., phone (301) 734-3266,