Monarch Butterflies' Fate Can Be Predicted By Milkweed Grown In CO2 Chambers

By growing milkweed in carbon dioxide-filled chambers, scientists can predict the fate of monarch butterflies.

While its population is already coming down, milkweed is its main source of food. In an experiment, scientists exposed milkweed to CO2 emissions that are thought to exist for a century with the rise in greenhouse gas emissions due to the burning of fossil fuel, according to the University of Michigan, said a report published by the University of Michigan.

The milkweed was then fed to hungry butterflies and caterpillars.

Past research has proved that a few species of milkweed generates lower levels of protective cardenolide toxins, which helps monarchs fight disease and parasites when they are "exposed to elevated levels" of cardioxide.

"When I heard that, it really set off an alarm," said U-M doctoral student Leslie Decker. "If toxins that are very active against parasites are decreasing under elevated CO2, what does that mean for the susceptibility of monarchs in the future?"

In their experiment, the scientists varied the exposure as well as feeding of the butterflies.

"We know exactly how many spores each caterpillar ate, as well as the exact dose of the milkweed toxin they received," said laboratory of ecologist Mark Hunter.

By finding out which species of milkweed help monarchs to fight off parasites, it would be possible to create a management plan involving planting beneficial species of milkweed, according to hngn.

"This is a way determine how elevated CO2 changes the chemistry of these plants and how those changes work their way up the food chain," Decker said. "At the same time, a lot of people reared monarch butterflies as children and still have a sentimental attachment to them. So our work may motivate some people to care more about the ways global change is altering our world."