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Butterflies near salted roads grow larger eyes and muscles

by Sandhya Sekar

You might be able to cut the salt in your diet, but the wildlife near salted roads doesn’t have a choice. It’s not all bad, though – salt may boost the brawn of butterflies.

When roads are salted in icy conditions, some of the run-off is taken up by plants. To find out if raised sodium levels in roadside plants might affect animals that feed on them, Emilie Snell-Rood at the University of Minnesota, St Paul, and her colleagues assessed local monarch butterflies, which feed on milkweed plants.

The team found that milkweed plants at the roadside contained 16 times as much sodium as those 100 metres away from the road. The butterflies reared on these plants had, on average, 6 times as much sodium in their bodies as those reared on prairie plants, and were less likely to survive beyond the caterpillar stage. But sodium is essential for the development of nerve and muscle tissue in animals, and those butterflies that did survive on high-sodium leaves also experienced a growth spurt: males had bigger flight muscles and females had significantly larger eyes…

(read more: New Scientist)

photograph by Bruce Coleman Inc./Alamy

(via rhamphotheca)