Scientists are evaluating several
species of Gonatocerus wasp (G. triguttatus is shown in top
photo) as candidates for helping to hold down the spread of grape and other
diseases transmitted by the glassy-winged sharpshooter. The sharpshooter is
roughly 15 to 20 times larger than its wasp natural enemies. Click the
images for more information about them.
Scientists Seeking Biocontrols Against
October 20, 2005
Help may be on the way from Agricultural Research Service (ARS) scientists in Argentina and Texas for
grape growers in California who are battling the glassy winged
A parasitic wasp could help growers ward off the glassy winged
sharpshooters (GWSS) that have been spreading plant-damaging Xylella
fastidiosa bacteria in southern California vineyards since the 1990s. Now
sharpshooters have made it to Hawaii and Tahiti. ARS scientists in Weslaco,
Texas, have shown that the invasive GWSS in California is from Texas--part of
the pest's native habitat.
X. fastidiosa causes a variety of costly plant diseases,
including Pierce's disease in grapevines and leaf scorch in oleanders. Grape
growers in Riverside and San Diego counties have lost about $38 million due to
For over a decade, ARS scientists and researchers at the
University of California-Riverside and the
California Department of Food and
Agriculture have been seeking biocontrol strategies to control the
At the ARS South American Biological Control Laboratory (SABCL) in Hurlingham, Argentina,
researchers have been evaluating wasps that lay their eggs inside GWSS eggs,
which are later consumed by the wasp young as they hatch and feed.
The primary candidate for this form of biological control is currently
Gonatocerus tuberculifemur from South America. G. tuberculifemur
is being tested at both the SABCL and the
Insects Research Unit in Weslaco, but the wasp has not yet been released.
Researchers in Weslaco are also searching for nymphal parasitoids in
their native range in Texas. To date, all the biological control
Gonatocerus species agents are egg parasitoids.
This and other ARS sharpshooter-related research is being highlighted
in the current issue of California
ARS is the U.S. Department of
Agriculture's chief scientific research agency.