Environmental Entomology (1993) 22, 993-1002

Mark A. Quinn, Patricia S. Johnson, Charles H. Butterfield and D.D. Walgenbach (1993)
Effect of grasshopper (Orthoptera: Acrididae) density and plant composition on growth and destruction of grasses
Environmental Entomology 22 (5), 993-1002
Abstract: A study was conducted to determine the effects of grasshopper density and plant composition on grass growth and destruction by the mixed grass- and forb-feeding grasshopper, Melanoplus sanguinipes (F.). Using a completely randomized design, 125 1-m-2 cages were placed on plots on mixed-grass rangeland in western South Dakota and stocked with 0, 5, 10, 15, or 20 fifth-instar M. sanguinipes. Grasshopper densities within the cages were monitored approximately weekly, and total grasshopper feeding-days were calculated for each cage for 68 d. Before adding grasshoppers, biomasses of grasses and forbs within the cages were estimated visually and after 68 d, final biomass of vegetation was determined. Results from analysis of variance with regression and multiple regression analysis indicated that grasshopper density and the initial biomass of western wheatgrass and shortgrasses within the cages significantly affected the final biomass and growth of western wheatgrass and the amount of grass removed by grasshoppers. However, significant reductions in grass biomass occurred only in cages stocked with 15 and 20 insects, equivalent to 845 and 1,112 grasshopper feeding-days, respectively. Grasshopper density had no significant effect on biomass of shortgrasses and Japanese brome, although growth of these species was affected by initial biomass of grasses in the cages.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)

Research topic(s) for pests/diseases/weeds:
damage/losses/economics

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Melanoplus sanguinipes	Grasses/turf/rangeland	U.S.A. (mid N)