Grazing animals help spread plant diseaseDecember 30, 2008CORVALLIS, Ore. - Researchers have discovered that grazing animals such as deer and rabbits are actually helping to spread plant disease - quadrupling its prevalence in some cases - and encouraging an invasion of annual grasses that threaten more than 20 million acres of native grasslands in California. The findings run contrary to what had been predicted by other theories, which had suggested that "consumers" such as deer would help to contain or reduce disease. They point once again to the complexity of natural ecosystems and the many ways in which plants, animals and even viruses interact with each other. The work will be published this week in Proceedings of the National Academy of Sciences, by researchers from Oregon State University, Cornell University and the University of North Carolina. "We usually think of a disease and its host as very tightly coupled, like a flu virus that infects humans," said Elizabeth Borer, an assistant professor of zoology at OSU. "But in natural ecosystems we're finding it's not nearly that simple, and to understand how plant pathogens work we have to consider the entire food web and many plant/animal interactions of which we are barely aware." The work is of particular importance, researchers said, because so many elements of ecosystems are undergoing rapid change, from human manipulation, climate change, increase or decrease in various species, new invasive species, and other factors. Any one of those changes could have ripple effects with seemingly unrelated diseases or other issues that are poorly understood - an increase in the abundance of white-footed mice, for instance, has been shown to increase Lyme disease risk in humans. In this study, scientists examined the effect of herbivores and omnivores such as mule deer, rabbits and feral pigs on the prevalence of barley and cereal yellow dwarf viruses, which can infect more than 100 crop and non-crop plant species, reducing their growth and seed yield. This virus is a major concern for cereal crop production around the world. In places where most plant eaters were kept out of test plots, the prevalence of this virus was only about 5 percent. It rose to 18 percent, a 3.6-fold increase, in areas that the animals grazed. The grazers did not directly spread the plant virus, researchers said. Rather, they increased the amounts of annual grasses that are preferred by the aphids which play a role in transmission of this viral plant disease. That allowed for a much greater prevalence of the virus in areas where grazing took place. "Even in complex natural communities, alternations to food web composition such as consumer invasion or extinction can lead to significant impacts that cascade through entire communities, including changes in infection risk," the researchers wrote in their report. Oregon State University |
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| Related Plant Disease Current Events and Plant Disease News Articles New 'biofactories' produce rare healing substances in the endangered Devil's claw plant Deep in Africa's Kalahari Desert lies the "Devil's claw," a plant that may hold the key to effective treatments for arthritis, tendonitis and other illnesses that affect millions each year. Plant protein 'doorkeepers' block invading microbes, study finds A group of plant proteins that "shut the door" on bacteria that would otherwise infect the plant's leaves has been identified for the first time by a team of researchers in Denmark, at the University of California, Davis, and at UC Berkeley. Iowa State researchers contribute climate model to study that finds some winds decreasing Declining wind speeds in parts of the United States could impact more than the wind power industry, say Iowa State University climate researchers. New wheat disease could spread faster than expected Both plant and human diseases that can travel with the wind have the potential to spread far more rapidly than has been understood, according to a new study, in findings that pose serious concerns not only for some human diseases but also a new fungus that threatens global wheat production. Does hotter mean healthier? Phytophthora blight, caused by Phytophthora capsici, is a major plant disease that affects many crop species worldwide, including chile peppers in New Mexico. Farmers' observations suggested that Phytophthora capsici caused less damage in pepper crops of the hot pepper varieties than low-heat pepper varieties. New hybrid plants could prompt more prodigious pepper production in Southwest By themselves or as an ingredient in a variety of foods, including salsa, America's top-selling condiment, peppers have found a warm spot in the hearts and stomachs of U.S. consumers. People only eat 1 when the chips are brown Dr. Don Henne isn't wasting his degree when he's standing by the deep fryer waiting for potato slices to turn brown. He's conducting research that will help the potato industry and consumers. Laurel Wilt of Redbay and Sassafras: Will Avocados be Next? Scientists with the USDA Forest Service Southern Research Station (SRS), Iowa State University, and the Florida Division of Forestry have provided the first description of a fungus responsible for the wilt of redbay trees along the coasts of South Carolina, Georgia, and Florida. Humans fostering forest-destroying disease Enjoying your August vacation? Well, (as they say in the summer movies) there's a killer in the woods. Its strike has been consistently quiet, sudden, and deadly. Californians urged to help reduce spread of Sudden Oak Death An update on the increased spread of Sudden Oak Death, a plant disease devastating many of California's coastal oak and tanoak trees, and information on what Californians can do to help reduce its spread will be presented during a news conference on plant diseases that are of importance to California's economy and agriculture. More Plant Disease Current Events and Plant Disease News Articles |
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