South American Biocontrols
This parasitic wasp,
Gonatocerus triguttatus, lays
its eggs in glassy-winged
sharpshooter eggs embedded
in leaves. Two new wasps,
G. tuberculifemur and
G. metanotalis, have recently
been found to attack this
sharpshooter's eggs as well.
Glassy-winged sharpshooters "have bred in huge numbers
in southern California, where they lack most of their natural enemies,"
says ARS entomologist Walker A.
Jones. As leader of the ARS Beneficial Insects Research Unit, Weslaco,
Texas, Jones directs an international effort to find nonchemical methods
to help stop this invasive leafhopper.
Jones is scouring South America in search of critters
that have potential as biological control agents in California.
But why travel to South America to solve a California
"Because sections of Chile and Argentina, for example,
have climates very similiar to those of some of California's prime agricultural
areas," explains Jones. "Some of those same 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 that state."
In a 2002 search of northern Chile and northwestern Argentina,
Jones and colleagues have found more than a half-dozen such natural
enemies of South American sharpshooters. Jones's main collaborators
were Guillermo Logarzo, with the ARS South American Biological Control
Laboratory in Hurlingham, Argentina, and Eduardo Virla, with an Argentine
agency, PROIMI, that does work similar to that of ARS.
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 toalbeit
slightly smaller thanits glassy-winged cousin.
The team also brought back seven other wasps, all of which
are stingless and harmless to humans. "Their only mission in life,"
Jones says, "is to attack sharpshooter eggs."
Jones considers the two Gonatocerus species the
most promising, in part because much is already known about them. Another
advantage: They are abundant in South America.
"Indoor tests," Jones says, "have shown
that these wasps successfully attack glassy-winged sharpshooter eggs.
That's impressive, considering that the glassy-winged is a species the
wasps have never come in contact withuntil now. This finding suggests
that the wasps will do very, very well in California."
Specialists with USDA's Animal and Plant Health Inspection
Service near Mission, Texas, are conducting the indoor tests of the
candidate biocontrol agents. Entomologists at the University of California,
Riverside, are carrying out additional screening, in collaboration with
Jones and experts from the California State Department of Food and Agriculture.
They'll identify the biocontrol candidates and ensure that the wasps
won't pose a threat to other organisms.
"We didn't expect to bring back so many potential
biocontrol agents," notes Jones. "It's a pleasant surprise."By
Flores, Agricultural Research Service Information Staff.
This research is part of Crop Protection and Quarantine,
an ARS National Program (#304) described on the World Wide Web at www.nps.ars.usda.gov.
"South American Biocontrols May Tangle With Glassy-Winged Sharpshooter" was published in the September 2003 issue of Agricultural Research magazine.