Monarch habitat in peril due to herbicide use, says report

An American environmental group says widespread use of glyphosate is killing milkweed and devastating monarch butterfly populations.


The Natural Resources Defense Council (NRDC) singles out glyphosate because of its widespread use, but states other herbicides can also damage the insect’s population.


“At the same time that spraying of glyphosate has soared, the monarch butterfly population has been plunging,” said Sylvia Fallon, an NRDC senior scientist in Washington D.C.


She said studies by the World Wildlife Fund indicates that the number of monarchs wintering in Mexico has dropped to 33.5 million, which is 10 percent of the annual average. That average is itself a far cry from the high of one billion recorded in 1997, the year after Roundup Ready crops were first introduced.


Most of the research data comes from the U.S. Midwest, where genetically modified soybeans and corn dominate farms. 


Monarchs, which migrate from Mexico to Canada and back again, depend on milkweed plants, the only source of food for the larvae.


In a petition filed with the U.S. Environmental Protection Agency in February, the NRDC asked for new safeguards to allow milkweed to grow. It also wants the EPA to fast track a review of glyphosate in 2015. 


Fallon said the petition states that glyphosate is one of many herbicides that can kill milkweed.


“To the extent that they impose any restrictions on glyphosate, they need to make sure it’s imposed on other herbicides because you don’t want to swap one out for the other, which is going to have the same effect on milkweed,” she said.


A blog posted by Monsanto said the company is talking with scientists about what might be done to help monarchs rebound and is eager to help rebuild monarch habitat.


“There’s no reason agriculture can’t coexist with natural wonders like monarch butterflies and their annual migration,” the blog said.


The NRDC petition asked the EPA for assessments and restrictions for both agriculture and non-agricultural uses. It suggested that the agency could prohibit herbicides along roads and power line rights of way and assess its use in horticulture and landscaping activities. 


It also asked that farmers create herbicide-free zones in and around their fields.