Elevated atmospheric concentrations of carbon dioxide reduce monarch tolerance and increase parasite virulence by altering the medicinal properties of milkweeds |
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Authors: | Leslie E. Decker Jacobus C. de Roode Mark D. Hunter |
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Affiliation: | 1. Department of Ecology and Evolutionary Biology, University of Michigan, Biological Sciences Building, Ann Arbor, MI, USA;2. Biology Department, Rollins 1113 O. Wayne Rollins Research Center, Emory University, Atlanta, GA, USA |
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Abstract: | Hosts combat their parasites using mechanisms of resistance and tolerance, which together determine parasite virulence. Environmental factors, including diet, mediate the impact of parasites on hosts, with diet providing nutritional and medicinal properties. Here, we present the first evidence that ongoing environmental change decreases host tolerance and increases parasite virulence through a loss of dietary medicinal quality. Monarch butterflies use dietary toxins (cardenolides) to reduce the deleterious impacts of a protozoan parasite. We fed monarch larvae foliage from four milkweed species grown under either elevated or ambient CO2, and measured changes in resistance, tolerance, and virulence. The most high‐cardenolide milkweed species lost its medicinal properties under elevated CO2; monarch tolerance to infection decreased, and parasite virulence increased. Declines in medicinal quality were associated with declines in foliar concentrations of lipophilic cardenolides. Our results emphasize that global environmental change may influence parasite–host interactions through changes in the medicinal properties of plants. |
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Keywords: | Anthropogenic
Asclepias
cardenolides
Danaus plexippus
global environmental change host– parasite interactions monarch butterfly
Ophryocystis elektroscirrha
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