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Overgrazed grasslands tied to locust outbreaks

ScienceDaily (January 27, 2012)

Overgrazed grasslands tied to locust outbreaks

ScienceDaily (January 27, 2012)

Scientists have shown that insect nutrition and agricultural land management practices may partially explain modern day locust outbreaks. Two juvenile Oedaleus asiaticus. Credit : Image courtesy of Arizona State University

During an outbreak year, locusts can populate over 20 percent of Earth’s land surface, negatively affecting more than 60 countries and the livelihood of one out of every 10 people.

The team’s initial experiments were designed to test the hypothesis that locusts form swarms partly to escape deteriorating conditions or to seek out better food sources. Most herbivores, including insects, are thought to be limited by obtaining sufficient protein. The researchers began, therefore, by fertilizing grassland plots with nitrogen. Their expectation was that the added nitrogen would raise the plants’ protein levels, enhance locusts’ survival and growth and stop locusts from swarming.

They couldn’t have been more wrong. Locusts fed on nitrogen-fertilized plots either died or grew more slowly. Puzzled, the scientists took a step back, examining which host plants these locusts preferred. The results showed that these locusts ate plants lower in nitrogen ; not higher.

Story Source

The above story is based on materials provided by Arizona State University.

Pour en savoir plus (ScienceDaily)

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