Electrify Glassy-Winged Sharpshooter Research
By Marcia Wood
September 8, 2003
The word "wired" has
taken on new meaning in California research about a grapevine enemy called the
glassy-winged sharpshooter. Agricultural
Research Service research entomologist Elaine A. Backus is attaching thin,
gold wires to the backs of these half-inch-long insects. She's also wiring
grapevines, growing in pots in her laboratory.
The little leafhopping insects complete the circuit for the low-level
current when they puncture the grapevines with their tube-like mouth parts, to
suck the plants' sap. The result? Backus can zero in on the minute-by-minute
action of these attacks.
Glassy-winged sharpshooters can transmit a deadly plant bacterium,
Xylella fastidiosa, into plants during feeding. This microbe can live in
the sharpshooter's gut without harming the insect. But when Xylella
moves from a sharpshooter into a plant, the bacterium can form colonies, or
clusters, that may eventually shut off the flow of water in the hapless
grapevines. Severely infected vines usually die within a year or two after
Backus is analyzing the patterns of electrical waves, somewhat like
electrocardiograms, that her instruments record as the sharpshooters feed
hungrily. From these charts, Backus intends to piece together new clues about
exactly when, how, and how quickly the Xylella microbes in the insect's
gut get dislodged and shuttled into the vine.
She also plans to use her electrical system to develop a method for easily
pinpointing superior grapevines that are resistant to the insect and bacterium.
When X. fastidiosa attacks grapevines, the infection that results is
known as Pierce's disease. Southern California winegrape vineyards were hit
hard with this disease in the 1990s soon after the sharpshooter first appeared
in the state.
Backus is based at the ARS San Joaquin
Valley Agricultural Sciences Center in Parlier, near Fresno. An article in
the September 2003
issue of the monthly magazine Agricultural Research tells more about her
investigations and those of her Parlier colleagues.
ARS is the U.S. Department of
Agriculture's chief scientific research agency.