Ag Today July 18, 2018

More bad news for monarch butterflies — study shows climate change’s devastating effect

Peter Fimrite July 18, 2018 Updated: July 18, 2018 6 a.m., The San Francisco Chronicle

Rising levels of carbon dioxide from car and factory exhaust — which scientists say is the primary cause of global warming — could contribute to the killing off of monarch butterflies by reducing the medicinal qualities of the plants they eat, a new study has found.

The University of Michigan experiment, co-authored by a Stanford University scientist, found that higher carbon dioxide levels reduced a natural toxin in milkweed that feeding caterpillars utilize to fight off parasites.

The 77 percent reduction in parasite tolerance found in the study is the first definitive example of how monarch survival, the plants they live and feed upon and the Earth’s changing climate are intricately linked.

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