EAST LANSING, Mich. (WLNS) – The eastern monarch butterfly has been on the decline for decades, and Michigan State University set out to uncover the cause.
The question is not just an issue of conservation for this iconic and charismatic insect. Butterflies, including monarchs, are prolific pollinators, including for major crops grown in Michigan.
However, their numbers have been falling fast. According to the research team led by MSU researcher Erin Zylstra, the biggest drop was from the mid-1990s to 2004. That’s when farmers started planting crops that were engineered to resist the weed killer glyphosate, allowing them to use the chemical much more liberally. This led to a major decline in milkweed plants, which are the only food source for monarch caterpillars.
However, since that time, several different causes have been contributing to the decline of the monarchs, and the biggest one has been climate change. Zylstra’s team was able to reach that conclusion with the help of local volunteers around the continent, who performed 18,000 surveys of adult butterfly populations around the continent.
While the diagnosis is not good news, Zylstra says figuring out the cause of the decline will help efforts to preserve monarch butterflies. For example, efforts to support milkweed for caterpillars can be focused on areas where climate change is unlikely to impact the monarchs’ breeding success.
For more information on this research, click here.