Four Potential Biocontrols Found for Controlling Giant
July 24, 2009
Four promising biological controls that
could curb the impact of the invasive plant giant reed in the United States
have been found in Spain by Agricultural
Research Service (ARS) scientists.
The giant reed, Arundo donax, has been particularly destructive in
the Southwest United States, where its an exotic and invasive weed of
riparian habitats and irrigation canals. But in its native Spain, the giant
reed is kept under control by a host of insects, and thats where the
scientists have made numerous trips to in search of biological controls to
bring back to the United States.
At the helm of the U.S. project is
Goolsby, an entomologist at the ARS
Insects Research Unit (BIRU) in Weslaco, Texas. Helping out with Goolsby's
efforts at Weslaco is entomologist
Moran, who has documented the traits, or biologies, of the candidate
biocontrol agents. The work builds upon research done earlier by former ARS
Biological Control Laboratory scientists Alan Kirk and Rouhollah Sobhian
and by Ray
Carruthers of the ARS
and Invasive Weeds Research Unit.
One of the biocontrol candidates, a scale insect called Rhizaspidiotus
donacis, attacks the reeds root. This insects release has been
recommended by the Technical
Advisory Group (TAG), a North American organization that oversees releases
of weed biological control agents.
Another of the biocontrol candidates, the Tetramesa romana wasp, was
released in Texas in April 2009. This wasp attacks the weeds main stem,
weakening the plant, reducing its overall height, and causing it to form galls
and put out side shoots.
The third promising biocontrol agent, the Arundo fly (Cryptonevra
spp.), eats the inside of new shoots of the plant, while the leaf sheath miner,
Lasioptera donacis, destroys the plants leaves.
The scale insectwhich has an outstanding reproductive capacity and
feeds on the part of the root known as the rhizome, where most of the plant
biomass occursshows the most promise of the four biocontrol candidates.
Debilitating the rhizome could have a big impact on the plants growth and
This biological control approach is sustainable over the long term and
complements mechanical and chemical control strategies. BIRU research leader
Adamczyk notes that the potential release of the scale is a major
accomplishment for the research unit.
more about this research in the July 2009 issue of Agricultural Research
ARS is the principal intramural scientific research agency of the
U.S. Department of Agriculture.