Insecticides drive butterfly declines

Insecticide use is a major factor causing a decrease in the size and diversity of butterfly populations across the Midwestern U.S., researchers found.

In a recent study published in PLOS ONE, researchers analyzed 17 years of data on land use, climate, pesticide application and butterfly populations across 81 counties in five Midwestern states to identify the biggest factors impacting butterfly populations in the region.

They found that insecticide use was most strongly linked not only to declines in the size of butterfly populations, but also to the number of species, causing an 8% drop in diversity. Crop seeds treated with neonicotinoid insecticides appeared to have the largest impact, including on the monarch butterfly (Danaus plexippus), whose decline has raised significant conservation concerns.

While climate change and land use changes are affecting butterfly populations, the researchers found, insecticides are having a greater impact.

Read the study in PLOS ONE.