Effect of Controlled Low Levels of SO2 on Grasshopper Densities on a Northern Mixed-Grass Prairie1

Abstract

A northern mixed-grass prairie was exposed to monthly median S0₂ concentrations of 73, 134, and 228 μg/m³ Total grasshopper density and the density of Melanoplus sanguinipes (F.) were significantly (P < 0.01) reduced by SO₂ treatment on late-growing-season dates within each year of SO₂ exposure. Grasshopper density tended to decrease with increasing SO₂ concentration. Sulfur dioxide did not alter the relative proportions of M. sanguinipes in the total population.