By Sonia Corona
The monarch butterfly no longer arrives in gigantic colonies in the forests of Michoacán and the State of Mexico (center of the country). The migration of this insect in North America has decreased significantly in the last decade, and experts in Mexico point to the United States as one of those responsible for the species losing its presence on the continent due to the excessive use of herbicides. The World Wide Fund for Nature (WWF) points out in its report on the Monarch Reserve of Mexico that in the last year the monarch butterfly occupied 0.67 hectares of forest, 44% less than the previous year and the worst record that has been had in the history of the migration of this species to Mexico. The organization, together with the Mexican authorities, have undertaken a program to improve the conservation of the forests to which these insects migrate during the winter, through programs where the forest owners take charge of their care.
According to WWF, in 2013 the degradation of the forest that houses the monarch butterfly occurred on eight hectares, half the previous year, of a reserve that covers 56,000 hectares. The causes of deforestation in the region have been mainly due to illegal logging in the State of Michoacán, as well as the droughts that affected the forests of the State of Mexico. “Mexico has made the care of the monarch butterfly sanctuary a priority. It is essential that the United States and Canada participate as well, but the reality is that we have not seen concrete actions on their part, ”says Omar Vidal, WWF Mexico director.
Monarch butterflies travel up to 4,000 kilometers from Canada to reach the Mexican forests. By crossing the Midwest of the United States they achieve the reproduction of the longest-lived generation of their species, which lives for eight months, and which is the one that finally reaches Mexico. Experts point out that the use of the herbicide roundup - made by the multinational Monsanto - prevents the growth of milkweed or milkweed, the plants where the entire reproductive process occurs.
Ranchers and peasants in the United States use this herbicide on soybean and corn plantations to prevent milkweed from competing with the growth of their crops. According to a study from the University of Minnesota, led by researcher Karen Oberhauser, the relationship between the decline of milkweed plants and the reproduction of the monarch butterfly is direct. From 1999 to 2010, the 58% decrease in the existence of the plant had an 81% impact on the reproduction of the insect. In February, the presidents of Mexico, Canada and the United States agreed at the Summit of North American leaders to install a working group that would address the decline in migration of the species.
"It is too early to have concrete results of what the United States is doing," explains Alfredo Arellano, director of special projects for the National Commission for Protected Areas (CONANP). The environmental institutions of Mexico estimate that in the United States some small actions have been taken to prevent a further loss of the monarch butterfly. “There is much hope that farmers and civil society will be the ones who participate more in the conservation of this migratory phenomenon ”, points out Arellano. Monarch butterflies have begun their advance towards Mexico. If all goes well, the first groups of insects will be in the forests of the center of the country in November. “Everything seems to indicate that they will arrive on time. They are very punctual, ”says Vidal.
They are moving at speeds of 75 to 130 kilometers per hour and are weathering the consequences of climate change, the threat of herbicides and the destruction of ecosystems in their wake.