Monarch butterfly, milkweed declines not driven by GMO crops, study shows

To get a better understanding of the monarch butterfly’s future, Jack Boyle built a time machine.

Boyle, a Mellon Postdoctoral Fellow of Environmental Science and Policy at William & Mary, has been using the web to mine millions of century-old botany records to track abundance patterns of milkweed in America. Contrary to claims made by scientists and activists for decades, he’s learned that genetically modified crops are not the main culprit for the decline of milkweed, the principal host plant for monarchs.

[Editor’s note: Read Viewpoint: There’s no one ‘butterfly-killing bogeyman’ to blame for declining monarch populations to learn more.]

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[T]he researchers were able to track the relative abundance of both monarchs and milkweeds for more than a century, from 1900 to 2016. They found that both monarchs and milkweeds increased during the early 20th century and recent declines are actually part of a much longer trend beginning around 1950.

“Herbicide resistant crops are clearly not the only culprit, and likely not even the primary culprit,” the paper states. “Not only did monarch and milkweed declines begin decades before GM crops were introduced, but other variables, particularly a decline in the number of farms, predict common milkweed trends more strongly over the period studied.”

Read full, original article: Research: Monarch butterfly declines began long before GMOs