The U.S Approves a Powerful New Pesticide Deadly to Monarch Butterflies
Is the monarch butterfly the new polar bear?
The iconic insect, whose numbers have plummeted from 1 billion to 35 million over the past two decades, is emerging as the latest symbol of environmental catastrophe: In this case, the impact of industrial agriculture, genetically modified crops, and skyrocketing pesticide use on wildlife.
The latest fight over the future of the monarch broke out on Wednesday, when the U.S. Environmental Protection Agency approved a powerful—and highly toxic—new weed killer called Enlist Duo. Made by Dow AgroSciences and designed to be sprayed on genetically modified corn and soybean crops, Enlist Duo combines glyphosate and 2,4-D in a formula that’s supposed to kill weeds that have developed a resistance to each of those individual pesticides.
One wild plant that has not developed defenses against growing pesticide use is milkweed, which is essential to the monarch’s survival.
The rapid growth in industrial agriculture has wiped out milkweed through much of the Midwest, as the development of corn and soybeans resistant to glyphosate has given rise to the widespread use of the herbicide to control weeds.
In 1991, for instance, farmers sprayed 18.7 million pounds of glyphosate on between 13 and 20 million acres annually; by 2009, they were applying 182 million pounds of the pesticide a year to more than 261 million acres, according to the EPA.
“Over the last decade, there has been a sharp decline in the monarch population that traverses the American Midwest and overwinters in Mexico,” wrote attorneys for the Natural Resources Defense Council in a February petition asking the EPA to restrict use of glyphosate. “By eliminating milkweed—the exclusive food source for monarch larvae—the pervasive use of glyphosate has contributed to the monarch’s decline.”
Environmental groups in August petitioned the federal government to protect the monarch butterfly under the Endangered Species Act, citing the steep fall in population and the eradication of its habitat.
Researchers found milkweed in half of Iowa farm fields in 1999. A decade later, only 8 percent of cropland contained milkweed, according to surveys cited by NRDC.
“Since 1996, the adoption of herbicide-resistant corn and soybeans has contributed to approximately 150 million acres of habitat loss for monarchs; this loss is likely to increase as uncultivated lands are increasingly converted into cropland planted with glyphosate-resistant crops,” wrote the NRDC attorneys.
The rapid expansion of genetically modified crops has also led to the use of another class of pesticides called neonicotinoids. Scientific studies have linked neonicotinoids to the mass die-off of honeybees that pollinate a third of the world’s food supply.
The NRDC on Wednesday asked the U.S. Court of Appeals for the D.C. Circuit to overturn the EPA’s approval of Enlist Duo for use in Illinois, Indiana, Iowa, Ohio, South Dakota, and Wisconsin. The agency is considering approving the spraying of Enlist Duo in 10 additional states.
EPA representatives did not reply to a request for comment by press time. But in a statement, the agency said its assessments of Enlist Duo “confirm that these uses meet the safety standards for pesticide registration and, as approved, will be protective of the public, agricultural workers, and non-target species, including endangered species.”
“Weeds are becoming increasingly resistant to glyphosate-based herbicides and are posing a serious problem for farmers,” the EPA stated. “This action will provide an additional tool to reduce the spread of glyphosate-resistant weeds. We are requiring a stewardship plan to ensure that use of Enlist Duo successfully manages weed resistance problems.”
Sylvia Fallon, a senior scientist with the NRDC in Washington, D.C., said that by approving Enlist Duo, the agency is fueling the development of ever-more-powerful and environmentally destructive pesticides.
“There would not appear to be an end game to this arms race,” Fallon said in an email. “You can’t solve the problem of pesticide resistance with more pesticides.”
She added, “As the current decision demonstrates, the future will involve more and more powerful pesticides—unless we can break the cycle.”