Submitted to: Metaleptea
Publication Type: Abstract Only
Publication Acceptance Date: June 9, 2001
Publication Date: August 19, 2001
Citation: BRANSON, D.H. EFFECTS OF GRASSHOPPER DENSITIES AND CLIMATE CONDITIONS ON GRASSHOPPER SURVIVAL AND REPRODUCTION. METALEPTEA. V. 21, P. 41. 2001. Technical Abstract: Although considerable research has been conducted on the population dynamics of grasshoppers, there are many unresolved questions regarding the mechanisms responsible for observed grasshopper population fluctuations. I experimentally examined the effect of grasshopper densities, climate, and vegetation on survival and reproduction of grasshoppers. The experiment was conducted in eastern Montana in a mixed grass prairie highly dominated by western wheatgrass (>90%). The dominant grasshopper species at the site were Melanoplus sanguinipes and Phoetaliotes nebrascensis. Grasshoppers were stocked in 4 density treatments and 2 climate treatments using 10 m2 cages, with 4 replicate cages per treatment. Grasshopper densities at the site averaged between 25 to 30 nymphal and adult grasshoppers per m2. Grass biomass declined over the summer, although high quality regrowth occurred late in the season after an 8 cm rainfall. Treatments affected both vegetation quantity and vegetation quality at the end of the experiment. The decline in grasshopper densities in the outside controls matched the decline in grass biomass. Shade and water treatments did not affect grasshopper survival at the end of the experiment. Although high density cages had higher numbers of grasshoppers remaining at the end of the experiment compared to low density cages, proportional surival was higher in low density cages. There was no effect of avian predation on grasshoppers, as grasshopper numbers did not differ between exclosures and controls.