More bad news for monarch butterflies. Rising atmospheric concentrations of carbon dioxide reduce the medicinal quality of milkweed leaves, thereby reducing the tolerance of monarchs to their protozoan parasites. Published in the journal Ecology Letters, research by Leslie Decker in our lab suggests that monarchs could get sicker as CO2 levels continue to rise. You can read about Leslie’s findings here, and watch a short video here.
Leslie’s results could have implications far beyond monarch butterflies. Many species of animal, including humans, rely on plants for medicines. If elevated CO2 reduces the medicinal quality of milkweed leaves, it might also reduce the potency of other medicinal plants. Do we really want to take that risk by continuing to emit such high levels of CO2 into our atmosphere?