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United States Department of Agriculture

Agricultural Research Service

Title: Infection of Melanoplus Sanguinipes Grasshoppers Following Ingestion of Rangeland Plant Species Harboring Vesicular Stomatitis Virus

Authors
item Drolet, Barbara
item Stuart, Melissa
item Derner, Justin

Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 9, 2009
Publication Date: May 15, 2009
Repository URL: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2681647/pdf/2368-08.pdf
Citation: Drolet, B.S., Stuart, M.A., Derner, J.D. 2009. Infection of Melanoplus Sanguinipes Grasshoppers Following Ingestion of Rangeland Plant Species Harboring Vesicular Stomatitis Virus. Applied and Environmental Microbiology. 75(10):3029-3033.

Interpretive Summary: To understand how sporadic outbreaks of vesicular stomatitis occur in cattle and horses in the western U.S. we must understand which insect vectors are important in amplifying, maintaining, and transmitting the virus to these animals. Migratory grasshoppers have been implicated as reservoirs and mechanical vectors of VSV. The grasshopper-cattle-grasshopper transmission cycle is based on the assumptions that 1) virus shed from clinically infected animals would contaminate pasture plants and remain infectious on plant surfaces, and 2) grasshoppers would become infected by eating the virally contaminated plants. Our objectives were to determine the stability of VSV on common plant species of U.S. Northern Plains rangelands, and assess the potential of these plant species as a source of virus for grasshoppers. Fourteen plant species were exposed to VSV and many were found to still be harboring infectious virus for up to 24 hours after exposure. When virus exposed plants were fed to grasshoppers, they became infected. These studies provide evidence that the grasshopper-cattle-grasshopper transmission assumptions are valid. Although plants and soil are thought of as a source of virus, no report to date confirms this. To examine a possible decontamination/deinfestation strategy in light of the virus survival results, a commonly used grasshopper pesticide was found to inactivate VSV upon contact. This is the first report demonstrating the stability of VSV on rangeland plant surfaces and suggests a significant window of opportunity exists for grasshoppers to ingest VSV from contaminated plants. Use of grasshopper pesticides on pastures would decrease populations of a virus-amplifying, mechanical vector, and may also decontaminate pastures, thereby decreasing inter- and intra-herd spread of VSV.

Technical Abstract: Knowledge of the many mechanisms of vesicular stomatitis virus (VSV) transmission is critical to understanding the epidemiology of sporadic disease outbreaks in the western U.S. Migratory grasshoppers (Melanoplus sanguinipes, Fabricius) have been implicated as reservoirs and mechanical vectors of VSV. The grasshopper-cattle-grasshopper transmission cycle is based on the assumptions that 1) virus shed from clinically infected animals would contaminate pasture plants and remain infectious on plant surfaces, and 2) grasshoppers would become infected by eating the virally contaminated plants. Our objectives were to determine the stability of VSV on common plant species of U.S. Northern Plains rangelands, and assess the potential of these plant species as a source of virus for grasshoppers. Fourteen plant species were exposed to VSV and assayed for infectious virus over time (0-24 hours). Viable virus recovery at 24 hours post exposure was as high as 73%. The two most common plant species in Northern Plains rangelands (western wheatgrass [Pascopyrum smithii] and needleandthread [Hesperostipa comata]) were fed to groups of grasshoppers. At three weeks post feeding, the grasshopper infection rate was 44-50%. Exposure of VSV to a commonly used grasshopper pesticide resulted in complete viral inactivation. This is the first report demonstrating the stability of VSV on rangeland plant surfaces and suggests a significant window of opportunity exists for grasshoppers to ingest VSV from contaminated plants. Use of grasshopper pesticides on pastures would decrease the incidence of a virus-amplifying, mechanical vector, and may also decontaminate pastures, thereby decreasing inter- and intra-herd spread of VSV.

Last Modified: 12/22/2014
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