Grasshopper species complexes of forage crops in the piedmont region of Virginia

Field collections of grasshoppers (Orthoptera: Acrididae, Tetrigidae, and Tettigoniidae) from twenty hayfield and pasture sites in twelve counties in Virginia were made in 1979 and 1980. Fifteen Acrididae, two Tetrigidae, and six Tettigoniidae species were found among the 20,793 grasshoppers collected. Melanoplus femurrubrum femurrubrum (DeGeer) dominated the acridid fauna in both years, comprising 76.0 and 86.97 in 1979 and 1980, respectively. Two collection methods, sweepnetting and drop trapping, were used. It was assumed that the drop trap gave an absolute estimate of population densities and that discrepancies between the two collections were due to failure of sweepnetting to reliably sample the complex. Sweepnetting was found to bias against Acrididae in favor of the tettigoniidae in the complex studied. With species grouped by feeding preferences (quilds), sweepnetting sampled head (inflorescence) feeders above mixed-forb feeders, and mixed-forb feeders above grass feeders. Compared with other Acrididae, M.f. femurrubrum was over-represented in sweepnet samples above the composite of the other acridids. Within its quild its representation did not differ from the drop trap samples. Differences in the composition of the species complex from site to site were examined according to quilds based on diet, and were correlated with measurable properties or the vegetation. The proportion of head feeders was positively correlated with the plant height. Mixed-forb feeders were negatively correlated. Other vegetation properties (grass/forb ratio and percent of ground cover) were themselves highly correlated with plant height, and yielded no patterns that were as strong as those with plant height.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Entomology

Department dc:contributor.department

Entomology

Grantor dc:publisher

Virginia Polytechnic Institute and State University

Year dc:date.issued

1984

Author dc:creator

• Williams, John T.

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en_US

Handle dc:identifier.uri

http://hdl.handle.net/10919/80317

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/80317