Effects on Insects of Cattle Grazing Mixed Prairie Rangeland

A hypothesis that there was no relationship between Insects and cattle grazing was tested. The study was conducted on pastures that were stocked lightly (S.L.), moderately (2x), and heavily (3x). The pastures were also grouped in to 2 blocks based on topographic differences. Insects were systematically sampled with sweepnets in July and August 1988, and vegetation data were obtained from quadrats In July 1988. Diversity, composition, distribution, and biomass of insects, were all affected by cattle grazing pressure. There were 20 families and 8 orders with most individual insects obtained on the S.L. pastures. The most insect families were observed on the 2x pastures. Three orders had over 50 percent of their members in a single stocking treatment, and the 2x pastures had the highest insect biomass. The diversity of insects was highest in the 2x pastures. Most of the relationships observed between insects plants and stocking rate were deemed chance; however, the distributions of leaf beetles (Chrysomelidae) and flies (Diptera) among treatments and weevils (Curculionidae) and soft-winged flower beetles (Melyridae) among blocks along with various correlations between insect numbers and plant weights were significant.