Nitrogen fertilizer 'could prevent locust swarms'

byy Li Jiao
A surprising finding promises a cheap and environmentally friendly way of controlling locust swarms, a major plague that devastates crops around the world.

Land erosion caused by heavy livestock grazing promotes locust swarms by lowering the nitrogen content in plants that locusts feed on, according to a study published in Science today (27 January).

Conversely, the study also found that locusts do not thrive on nitrogen-rich food, as previously thought, but are in fact hampered by it.

"Nitrogen fertiliser - which plants use to make protein - may be an inexpensive, more environmentally friendly pest control solution for this species," said the lead author Arianne Cease, a researcher at Arizona State University, United States.

Most herbivores, including insects, are thought to be limited by the availability of nitrogen-rich protein in their diets.

But scientists were surprised to find that this is not the case for Oedaleus asiaticus, a dominant locust of the north Asian grasslands and a close relative of the common African pest O. senegalensis.

Field observations found that locusts were less likely to survive in fields that were fertilised with nitrogen, and their density was highest in the most heavily grazed fields - which were dominated by plants with low nitrogen content. Laboratory experiments showed that locusts preferred to eat plants with low nitrogen content.


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