Effects of Livestock Grazing on Grasshopper Abundance on a Native Rangeland in Montana

Abstract

Livestock grazing can affect habitat quality for grasshoppers through effects on food and oviposition site availability, microclimate, and other factors. Because of this, some authors have suggested that grazing programs can be used to help manage pest grasshopper populations. In a 6-yr study, we controlled access of cattle to replicated experimental plots on an Agropyron spicatum/Poa sandbergii pasture to create consistent year-to-year differences in postgrazing plant cover, with resultant affects on microclimate. After sampling grasshoppers multiple times after grazing treatments each summer, we found evidence of between-treatment differences in grasshopper abundance for the entire assemblage during 4 of the 6 yr. Some species, including Melanoplus sanguinipes (perhaps the worse rangeland grasshopper pest in the western United States), tended to be more abundant on ungrazed plots, whereas Melanoplus gladstoni often had greater densities on heavily-grazed plots. The effect of grazing on grasshopper densities in this study was lower in magnitude and less consistent among years than in a study we conducted simultaneously at a nearby site where the vegetation was dominated by the exotic species crested wheatgrass (Agropyron cristatum). Our results generally support proposals that grazing could be used to reduce pest grasshopper densities, although the effectiveness of a particular grazing scheme may vary among sites, years, and grasshopper and vegetation assemblages.

Landscape level patterns of grasshopper communities in Inner Mongolia: interactive effects of livestock grazing and a precipitation gradient

“…With in insect assemblages, however, species may respond differently to these changes in plant communities (Capinera and Thompson 1987;Miller and Onsager 1991;Dennis and Brusven 1995;Marini et al 2008;Branson and Sword 2010;O'Neill et al 2010). To separate the effects of land use and annual precipitation on plant communities and sub sequent effects on grasshopper communities at the landscape scale, we took simultaneous measurements of all these parameters across a precipitation gradient.…”

Impacts of grazing intensity and increased precipitation on a grasshopper assemblage (Orthoptera: Acrididae) in a meadow steppe

“…Grasslands are managed ecosystems, and one of the key management tools is grazing by large herbivores that are recognised as exerting one of the greatest effects on grassland ecosystems (Bagchi & Ritchie, 2010;Gill, 2015). A growing number of studies have generated great interest in understanding the ecological effects of grazing on grasshoppers owing to food and habitat (Jonas & Joern, 2007;O'Neill et al, 2010;Zhu et al, 2015). Meanwhile, with further climate change still expected, precipitation patterns may be more spatially heterogeneous and less predictable than temperature and CO 2 concentration (Beier et al, 2012), and grassland ecosystems are expected to be especially vulnerable to altered precipitation (McCluney et al, 2012).…”

Linking traits between plants and invertebrate herbivores to track functional effects of land‐use changes

“…Such plant traits are likely to sustain grasshopper species with a large head (Bernays & Hamai ) and mandibles (Isely ), while influencing oviposition site substrate due to the overall change in the canopy structure of the herbaceous layer, with both patches of bare soil among grass clumps due to trampling effect and accumulated unpalatable plant litter (O'Neill et al. ). Based on Specht et al.…”