New studies demonstrate that too much protein can be detrimental to the locust, Oedaleus asiaticus, and that swarms of these locusts are more likely to occur where vegetation is low in nitrogen content. Unfortunately for many farmers, erosion and heavy grazing by livestock both decrease the amount of nitrogen (and consequently, protein) in crops, thereby increasing the chances of a locust swarm. Arianne Cease and colleagues, along with most researchers, knew that optimal diets provide organisms with just the right amount of protein. But, they weren’t sure how sub-optimal diets might affect species in the wild. So, the researchers studied this particular species of locust, which is a major pest on the north Asian grasslands, and discovered that high-nitrogen diets decreased both the size and viability of the insects. These locusts seem to prefer eating plants with low nitrogen levels and artificial diets with low protein but high carbohydrate levels, according to the researchers. Plant nitrogen levels were lowest and locust abundance was highest in heavily grazed fields where the soils had been depleted of nitrogen, they say.
Article #19: "Heavy Livestock Grazing Promotes Locust Outbreaks by Lowering Plant Nitrogen Content," by A.J. Cease; J.J. Elser; C.F. Ford; J.F. Harrison at Arizona State University in Tempe, AZ; S. Hao; L. Kang at Chinese Academy of Sciences in Beijing, China.