Grasshoppers Can Transmit Virus to Livestock
August 26, 2009
Rangeland plants may be harboring a
virus that grasshoppers are transmitting to cattle, horses and other hoofed
mammals, according to a published research study by
Agricultural Research Service (ARS)
A recent outbreak of vesicular stomatitis virus (VSV) in the southwest
United States has disrupted rodeos and prompted quarantines. VSV is a viral
disease that causes sporadic outbreaks in the United States, most recently in
Drolet at the ARS
Animal Diseases Research Laboratory (ABADRL) in Laramie, Wyo., and
Derner at the ARS
Grasslands Research Station in Cheyenne, Wyo., have shown that under
laboratory conditions, rangeland plants can harbor VSV and pass the virus to
This research, published recently in the journal Applied and Environmental Microbiology, is
the first to demonstrate the stability of VSV on rangeland plant surfaces.
Although rarely fatal, VSV causes painful blisters on cattle, horses and
other hoofed mammals. During outbreaks, infected animals salivate heavily and
shed virus, which results in direct animal-to-animal transmission. Soil and
plants have been hypothesized to be virus sources, but current recommendations
for VSV control do not include decontamination of corrals and pastures.
To determine the window of opportunity for grasshoppers to ingest viable VSV
from contaminated plants, Drolet and Derner selected 14 rangeland plant species
that grasshoppers eat and exposed the plants to VSV in a laboratory setting. In
the lab, several species harbored viable virus for up to 24 hours.
The scientists then exposed two plant species to VSV and fed them to
grasshoppers 24 hours later. The grasshoppers became infected. These results
support the hypothesis that grasshopper-cattle-grasshopper transmission of VSV
The scientists next tested a common grasshopper pesticide and found that, in
addition to reducing the grasshopper population, the pesticide inactivated VSV
upon contact, thereby reducing a source of virus for livestock and
grasshoppers. Although such use would require additional
U.S. Environmental Protection Agency
registration, the pesticideor a similar virus-inactivating
spraymight help limit VSV outbreaks.
The results of this study could be useful in making disease management
decisions during future outbreaks, not only by offering a potential control
method, but by making it possible to assess risk more accurately.
ARS is the principal intramural scientific research agency in the
U.S. Department of Agriculture.