Scared Grasshoppers Affect Soil Chemistry
Grasshoppers who die frightened leave their mark in the Earth in a way that more mellow ones do not, U.S. and Israeli researchers said Thursday.
"So, indeed this sounds a little bit weird," lead author Dror Hawlena said in an audio interview posted on the journal Science's website.
Hawlena, a researcher at the Hebrew University of Jerusalem, along with colleagues at Yale University devised a test to measure the legacy of grasshoppers who were scared by spiders.
They placed cages in areas of natural vegetation and allowed some grasshoppers to be alone while others were placed in cages with a spider.
They glued the mouths of the spiders shut in order to make sure that the grasshoppers experienced pure fear but were not actually killed by the predators.
When the grasshoppers died, Hawlena took their bodies back to the lab and deposited them in soil.
He found that the body composition of the frightened grasshoppers was changed -- their carbon to nitrogen ratio was about four percent higher than their calmer peers.
But that rather tiny difference caused plant matter to decay much more slowly than it did in comparison tests using grasshoppers who died more peacefully.
Hawlena said the findings shed light not only on how predators and prey influence the makeup of the soil, but how stresses invoked by drought and extreme heat might have lasting effects on crops and growth cycles.