Sodium chloride, in the form of rock salt, is a common remedy for icy roadways. Although it makes driving easier, the heavy use of road salt has alters patterns of sodium availability. There has been little research on the impact on animals and insects. To address this, researchers have begun to look at butterflies.
A research team have studied
monarch butterflies, which feed on milkweed. The habitat examined is along the county roads near Cedar Creek Ecosystem Science Reserve in East Bethel, MN. By examining plants, the researchers found that road salt runoff can elevate sodium concentrations in the tissue of some plants by as much as 30 times the normal rate.
Researchers found that road salt runoff can elevate sodium concentrations in the tissue of some plants by as much as 30 times the normal rate. When the butterflies feast on the plants, they experience a subsequent bump in sodium levels, which can have different effects depending on the sex of the butterfly. For example, males increase in flight muscle while females show the opposite pattern. At higher levels, excessive sodium led to a markedly higher mortality rate.
The findings so far suggest that further study in urban areas with higher concentrations of road salt is needed.
The findings have been
published in the
Proceedings of the National Academy of Sciences, in a paper titled “Anthropogenic changes in sodium affect neural and muscle development in butterflies.”
