Grasshopper Ecology and Preventative Management
Latest Research Findings, Reports, and Publications for this Project
World-wide, grasshoppers and locusts are among the most economically important pests. Grasshoppers are an important native component of grassland ecosystems in the U.S., playing a role in nutrient cycling and serving as a critical food supply for wildlife. However, grasshoppers often reach outbreak densities in western North American grasslands, causing significant economic impact to the grazing industry from feeding, especially during drought periods when forage is already scarce. In addition, these outbreaks serve as a source of mass migration from large expanses of public rangeland to adjacent private cropland. It has been estimated that grasshoppers annually destroy on average at least 21 to 23% of available range forage in the western U.S. Traditional crisis-directed chemical control programs are economical only under certain conditions, do not provide predictable long-term control, have potentially important non-target effects, and may even exacerbate grasshopper problems.
Due to the historical emphasis on grasshopper outbreak suppression and intervention, ecologically-based preventative management of grasshoppers has received limited attention. We are examining the use of habitat management techniques such as burning or livestock grazing on rangeland as a method of manipulating the quality of habitat available for grasshoppers and/or their primary predators, and as a result, reducing grasshopper outbreaks. A promising ARS study found that during an outbreak period both grasshopper densities and forage consumption were five to nine times lower in twice-over-rotational grazing pastures than in season-long grazing pastures. We have also found that late-summer or fall fires in the northern Great Plains lead to reduced grasshopper populations in the year following a fire, suggesting that fire may be useful as a management tool for grasshoppers.
Although grasshopper herbivory can have negative economic consequences, it may also have important ecological consequences of interest to land managers and conservation organizations such as effects on plant community structure and rangeland productivity. We are examining how grasshopper herbivory affects nutrient cycling and multi-year plant productivity, with a collaborator from the University of Notre Dame. Results indicate that selective grasshopper herbivory acts to increase nutrient cycling and plant production at some sites.
Contributing Scientists: David Branson (Entomologist)
Latest Research Findings/Reports
Effects of summer fire and post-fire grazing on grasshopper abundance and species composition
By: David H. Branson (Entomologist) & Lance T. Vermeire
Download this Poster (PDF: 1.57 MB)
Rangeland management practices such as burning or livestock grazing have the potential to be important tools in grasshopper management, by manipulating the quality of habitat available for grasshoppers and/or their predators.
The following recent publications are available to download in .PDF format:
Branson, D. H. 2006. Life-history responses of Ageneotettix deorum (Orthoptera: Acrididae) to host plant availability and population density. Journal of the Kansas Entomological Society. 79:146-155. (PDF; 81KB)
Branson, D. H. 2005. Effects of fire on grasshopper assemblages in a northern mixed-grass prairie. Environmental Entomology. 34(5): 1109-1113. (PDF; 76KB)
Branson, D. H. 2005. Direct and indirect effects of avian predation on grasshopper communities in northern mixed-grass prairie. Environmental Entomology. 34(5): 1114-1121. (PDF; 113KB)