wasp, Gonatocerus triguttatus, lays its own eggs inside those of the
glassy-winged sharpshooter. Click image for additional information.
story to find out more.
Searching South America for Sharpshooter
Biocontrols By Alfredo Flores
September 10, 2003
Two tiny wasps from South America are among the top candidates
as biological controls for the glassy-winged sharpshooter, a pest that attacks
citrus crops and has caused problems for grape growers in California.
The pest has bred in large numbers in southern California, a
region that lacks most of the insect's natural enemies.
Agricultural Research Service
entomologist Walker Jones at the Kika de
la Garza Subtropical Agricultural Research Center in Weslaco, Texas, is
leading an international effort to find nonchemical methods to stop this
Sections of South America, particularly Chile and Argentina,
have climates that are very similar to those of some of California's prime
agricultural areas. Some of those sections of South America also have
sharpshooters that are close relatives of the glassy-winged sharpshooter. Given
the similarities to California climates, South American biological control
agents should already be pre-adapted to the Golden State, according to Jones.
In a 2002 search of northern Chile and northwestern Argentina,
Jones and colleagues found more than a half-dozen such natural enemies of South
American sharpshooters. Jones' main collaborators were Guillermo Logarzo, with
the ARS South American Biological Control
Laboratory in Hurlingham, Argentina, and Eduardo Virla, with an Argentine
agency called PROIMI
(Planta Piloto de Procesos Industriales Microbiológicos), which does
work similar to that of ARS, the U.S. Department
of Agriculture's chief scientific research agency.
Their top two biological control prospects have turned out to be
tiny wasps, Gonatocerus tuberculifemur and G. metanotalis. These
wasps have been known to attack the eggs of a South American sharpshooter,
Tapajosa rubromarginata. This insect is very similar to--albeit slightly
smaller than--its glassy-winged cousin.
The scientists also brought back seven other wasps, all of which
are stingless, harmless to humans, and only attack sharpshooter eggs. Jones
considers the two Gonatocerus species the most promising, in part
because much is known about them. They are also abundant in South America.
Read more about this research in the September issue of
Agricultural Research magazine, available