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K-State Today

March 23, 2021

Paper about grasshopper population decline named 2020 PNAS Cozzarelli prize finalist

Submitted by Jennifer Rhodes

A recent paper by Ellen Welti, K-State graduate, and co-authored by Anthony Joern,  university distinguished professor emeritus of biology, was selected a finalist for the 2020 Cozzarelli Prize.

The Editorial Board of the Proceedings of the National Academy of Sciences, or PNAS, annually selects papers published within the previous year to receive the Cozzarelli Prize. The annual Cozzarelli Prize recognizes research papers that reflect scientific excellence and originality. In 2020, winning papers were chosen from more than 3,600 articles appearing in the journal.

Welti's paper, "Nutrient dilution and climate cycles underlie declines in a dominant insect herbivore," analyzed potential reasons for observed grasshopper population declines of more than 30% over the past two decades at Konza Prairie. The decline was not caused by lack of food, as the amount of grass on the prairie has been increasing. Welti and other researchers began to wonder if the nutritional content of the grasses caused the decline. Using grass samples collected at Konza Prairie over the last 20 years, these researchers found lower levels of nitrogen, phosphorus and potassium in plants from recent years, suggesting that increasing levels of atmospheric CO2 are diluting the concentration of nutrients in grass biomass.

"While rising CO2 generally increases plant growth, per-bite concentration of key nutrients also decrease," Welti said. "This paper shows that this nutrient dilution effect may be a hidden cause of insect declines."

Welti's study used Konza Prairie's long-term grasshopper and plant composition data. Grasshoppers have been collected and surveyed at Konza for almost 30 years as part of the National Science Foundation’s Long-Term Ecological Research, or LTER, program.

Most recently, grasshopper research at Konza was led by Joern, who served as Welti's doctoral advisor at K-State.

Other authors are  Michael Kaspari, Welti's postdoctoral advisor, and Kirsten de Beurs, both from the University of Oklahoma, and Karl Roeder, U.S. Department of Agriculture-Agricultural Research Service, South Dakota.

Welti is currently a postdoctoral researcher at the Senckenberg Research Institute and Natural History Museum in Frankfurt, Germany.