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Tiny Transmitters Gauge Cricket
Movements By Erin
September 26, 2003
Mormon crickets were on the move again this summer. In bands up
to three miles deep and one mile across, they marched across several western
states, devastating croplands and bewildering residents as they blanketed
roadways and the sides of buildings.
But this time something else was moving with them. A team of
researchers, led by Agricultural Research
Service scientist Gregory Sword, was tracking the insects. For the first
time, researchers aimed to find out how far the flightless Mormon
cricketthat looks more like a grasshoppercould move in a day. Their
surprising discovery? One cricket walked more than one-and-a-quarter miles
across steep hills and valleys.
Researchers are investigating Mormon crickets' travels in hopes
of one day predicting their movements. At outbreak levels, the two-inch-long
insects walk in bands of millions of individuals, consuming most plants in
their path, including crops, grasses and ornamentals.
Up to now, researchers estimated the insect could move about a
mile a day. In July, to determine the pest's true mobility, Sword, Pat Lorch
from the University of North Carolina and
Darryl Gwynne from the University of
Toronto charted the migration habits of 12 Mormon crickets in northwestern
Colorado. Sword is an ecologist at the ARS
Northern Plains Agricultural Research
Laboratory in Sidney, Mont.
Micro-radio transmitters, about one-quarter of the insect's
weight, were glued to individual crickets. These transmitters provided signals
so that the team could find the same insects 24 hours later.
The ultimate goal, says Sword, is to develop a model that
predicts where migrating cricket bands will move next. Knowledge of a band's
future change in direction, for instance, would allow land managers to pinpoint
pesticide applications, reducing exposure of nontarget species.
Generally, Mormon crickets play an important role in western
environments by providing food for wildlife and contributing to nutrient
cycling on rangelands.
ARS is the U.S. Department of
Agriculture's chief scientific research agency.