Monarch Butterfly Population Dwindles with Rise of Herbicide

The number of Monarch butterflies reaching Mexico has been falling for years, and it has now reached the lowest level on record, according to the Salt Lake Tribune. The World Wildlife Fund announced this week that butterflies this winter were found in 1.7 acres across 11 sanctuaries, down from a high of 45 acres in 1996.

The lifecycle of the Monarch butterfly is synchronized with the seasonal growth of the milkweed, the only plant its larvae will eat. While it once grew abundantly in grasslands, roadsides and cornfields, the milkweed population took a hit when agriculture boomed.

More than a million acres of Upper Midwest grassland have been plowed under in recent years for corn and soybean fields - a rate of loss comparable to deforestation in places like Brazil and Indonesia.

Yet the most critical development for the Monarchs was the emergence of Roundup Ready corn and soybeans. These genetically modified crops were designed to withstand the herbicide Roundup, a weed killer created by the Monsanto Company. This enabled farmers to destroy weeds, including the milkweed, and maximize their yield.

Once Roundup Ready corn and soybeans started to spread, Monarch butterfly egg production declined rapidly.

"We have this smoking gun," Karen Oberhauser, a conservation biologist at the University of Minnesota, said. "This is the only thing that we've actually been able to correlate with decreasing monarch numbers."

The outlook appears bleak. In 2013, 83 percent of all corn and 93 percent of soybeans in the United States were herbicide tolerant, totaling nearly 155 million acres, much of it in the Midwest.

Experts estimate that soon enough, there will essentially be no Monarchs in the Midwest. Considering that this area is the birthplace of nearly half of all Monarchs east of the Rocky Mountains, it will be difficult for the butterfly to recover there if the milkweed does not. Their declines will mirror each other.

While the Monarch is not a candidate for the Endangered Species Act yet, there is concern that the yearly mass migration to Mexico could disappear. Butterfly advocates are hoping the agribusiness industry will throw some money and marketing behind campaigns to get people to plant more milkweed elsewhere.

(Source by: Designntrend.Com )

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