Grasshoppers may be experiencing their own type of famine due to rising levels of carbon dioxide. AAAS reports that over the past five years, many studies have been documenting dwindling insect populations to the point that the phrase “insect apocalypse” has been coined.
Ellen Welti, a postdoc student of ecologist Micahel Kaspari at the University of Oklahoma, is concerned with the decline in insect populations and has been analyzing data on 44 species of grasshoppers. Welti’s analysis has taken place at the Konza Prairie Biological Station in Kansas where she has been tracking population trends in two surveys of grasshopper abundance. She has noticed that grasshoppers have declined by 30% over two decades. “I was actually quite surprised,” she told AAAS. At first, she and her colleagues assumed that habitat loss and pesticides were the major reasons as to why grasshoppers have been declining, but these factors are not in play on the Konza Prairie.
Weltie and Kaspari thought that another global trend could be an issue — such as increased carbon dioxide levels. High carbon dioxide levels in plants such as wheat, maize, rice, and other crops mean that they do not accumulate as much nitrogen, phosphorous, and other nutrients, according to a Harvard University demonstration in 2014 by planetary health scientist Samuel Meyers. The idea from this is that roots cannot keep up with the growth stimulated by the extra carbon and simply don’t provide the right amounts of the other elements.
Most of the concern has been focused on human health since that revelation — if we are eating plants that normally have a certain amount of nutrients but are no longer getting those nutrients due to excess carbon dioxide levels, then we are pretty much eating empty calories. Imagine — if we aren’t getting the needed nutrients, how does this affect insects that also rely on these plants for nutrition?
Welti was able to do more research on 30 elements in samples of various grass species collected and stored by the Kansas LTER every year. Her research determined that the biomass of the grasses doubled over the past 30 years while the plants’ nitrogen content declined about 42%. Other elements that showed decline were phosphorous by 58%, potassium by 54%, and sodium by 90%. Kaspari’s team shared the findings in the Proceedings of the National Academy of Sciences.