Biocontrol Beetles Set Free to Tackle Saltcedar

By Kathryn Barry Stelljes
May 22, 2001

Chinese leaf beetles (Diorhabda elongata) are beginning official duty as the first biological control agents released into the environment against saltcedar (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, saltcedar 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 safety.

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 saltcedar that has crowded out their native willow nesting sites.

Biological control is expected to slowly reduce saltcedar, allowing beneficial plant and animal species to reestablish in severely infested areas. Other planned activities include continued monitoring of the insects, plants and associated wildlife, and studies to facilitate revegetation with native plants.

The project, initiated and coordinated through USDA’s Agricultural Research Service, operates in conjunction with a consortium of more than 30 federal, state, and local agencies; universities; and private organizations. The team received a $3 million grant in 2000 from the USDA's Initiative for Future Agriculture and Food Systems for work on a complex of invasive weeds, including saltcedar.

ARS is USDA’s chief scientific research agency.

Scientific contacts: C. Jack DeLoach, ARS Grassland, Soil and Water Research Laboratory, Temple, Texas, phone (254) 770-6531, fax (254) 770-6561, deloach@brc.tamus.edu; Raymond I. Carruthers, Exotic and Invasive Weeds Research Unit, ARS Western Regional Research Center, Albany, Calif., phone (510) 559-6127, fax (510) 559-6123, ric@pw.usda.gov.