Biocontrol beetles set free to tackle salt cedar
Chinese leaf beetles (Diorhabda elongata)
are beginning official duty as the first biological control agents released into
the environment against salt cedar (Tamarix spp.).
These invasive trees, which can grow up to
30 feet tall, infest more than 1 million acres along western waterways. In
addition to crowding out native plants, salt cedar can increase soil salinity,
divert natural streamflow and increase wildfire frequency.
Unprecedented monitoring of the beetle and
its impacts began in July 1999, when the insects were put out in large cages at
10 locations in six western states.
Scientists first released the beetles from
field cages last week near Seymour, Texas, and Pueblo, Colo. They plan to make
other releases near Bishop, Calif.; Fallon, Lovelock and Schurz, Nev.; Delta,
Utah; and Lovell, Wyo. Additional nursery cages are being established at new
sites near Woodland and King City, Calif.
Biological control agents are often
released directly into the environment. In this case, the U.S. Department of
Agriculture and cooperating scientists are watching these beetles closely to
ensure their establishment and to evaluate their impact, population growth and
This information has been used to ensure
that the biocontrol project protects all native species in the area, including
the southwestern willow flycatcher, Empidonax traillii extimus. In some
locations, these endangered birds nest in salt cedar that has crowded out their
native willow nesting sites.