Monarch expert wants to keep the record straight

| January 31, 2014

Lincoln Brower wants to be absolutely clear about the No. 1 threat to the annual migration of monarch butterflies.

“Genetically modified corn and soybean [cultivation] is the culprit,” he says.

Specifically, the expansion of these crops — which are engineered to resist herbicides that kill the monarch’s milkweed host plants — is destroying the monarch’s breeding grounds and primary food source along its migration routes in the Midwestern U.S.

Overwintering monarch butterflies cluster on fir boughs in central Mexico.

It’s not that the species is in danger of extinction. There are populations in other parts of the world. There is real fear, however, that the multigenerational flight of millions of butterflies across North America to their overwintering grounds in Mexico would cease. That would be a tragic loss, says Brower, a research biologist at Sweet Briar and world-renowned expert on monarchs.

He likens the phenomenon — which he and his colleagues have struggled for decades to explain and still do not fully understand — to a work of art wrought by nature. He believes we should value it as we do manmade art and culture. Indeed, the monarchs’ arrival en masse in the mountains of central Mexico each fall is not only integral to the local heritage, as an ecotourism draw, it is important to the economy.

The mystery and imagery of the black and orange butterflies’ migration has the world’s attention. When the World Wildlife Fund, Mexico’s Environment Department and the Natural Protected Areas Commission released a report on Jan. 29 documenting both steep and sustained declines in the monarch’s population, the story appeared around the globe, from nightly newscasts to community newspapers.

The monarchs winter in a small zone around the border of the states of Mexico and Michoacán, where they depend on specialized fir forests and their microclimate to thrive. Loss of habitat through illegal logging has also been blamed for their decline, and extreme weather events in fall 2012 and spring 2013 likely contributed to the precipitous drop this year and last.

Some of the news coverage in the past two days concerns Brower. He worries that secondary causes, such as extreme weather, will dominate public discussion, taking the focus away from the real foe. Healthy populations can recover from setbacks due to weather, which, in the short term, we can’t do anything about anyway, he says.

But GMO crops and herbicides in the U.S. “lead to the wholesale killing of the monarch’s principal food plant, the common milkweed,” he told the Associated Press (“Monarch Butterflies Drop, Migration May Disappear”).

These are issues he wishes reporters and policymakers would confront head on. He notes the damage isn’t likely to be limited to monarchs.

“Which species are next and how soon will this industrialized agriculture backfire on humanity?”

Jennifer McManamay

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Category: Biology