Grasshopper's fear harms ecosystem

Grasshoppers, stressed by the fear of an attack by spiders, could harm our ecosystem dearly by consuming a greater quantity of carbohydrate-rich plants, similar to what humans under stress do - eat more sweets, according to researchers.

This type of reaction will, in turn, cause chemical changes in the grasshopper and in its excretions, affecting the ecosystem it inhabits, according to researchers from the Hebrew University of Jerusalem and at Yale University, US.

When the scared grasshopper dies, its carcass, now containing less nitrogen as a result of its diet change, will have an effect on the microbes in the ground, which are responsible for breaking down animals and plants, the journal Science reports.

With less nitrogen available, the microbes will be decomposing the hard-to-break-down plant materials in the soil at a slower rate. Thus, the fear of predation may slow down degradation of complex organic materials to the simpler compounds required for plant growth.

Research on this biological-ecological phenomenon was carried out by Dror Halwena of the Department of Ecology, Evolution and Behaviour at the Hebrew University of Jerusalem, along with researchers at Yale.

The scientists exposed grasshoppers to spiders in order to arouse the stress reaction. They also used a group of non-stressed grasshoppers. The scared grasshoppers had a higher carbon-to-nitrogen ratio in their bodies than non-scared grasshoppers, according to Hebrew and Yale statement.

“We are dealing here with an absolutely new kind of mechanism whereby every small chemical change in a creature can regulate the natural cycle, thus in effect affecting the ecology in total, such as the amount of carbon dioxide released into the atmosphere (through decomposition) and field crop productivity. This has tremendous consequences for our ecological understanding of the living world,” said Halwena.