Author
BESS, JAMES - MSU, DEPT ENT. BOZEMAN,MT | |
O'NEILL, KEVIN - MSU,DEPT ENT. BOZEMAN,MT | |
Kemp, William - Bill |
Submitted to: Western North American Naturalist
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 4/12/2004 Publication Date: 10/29/2004 Citation: Bess, J.A., O'Neill, K.M., Kemp, W.P. 2004. Leafhopper assemblages on native and reseeded grasslands in southwestern Montana. Western North American Naturalist. 64(4):518-531. Interpretive Summary: Leafhoppers, like grasshoppers, are very common throughout the grasslands of North America. However, unlike the case with grasshoppers, we know very little about vegetation preferences among the many leafhopper species present, information that is useful in range management as well as conservation biology. In this study, we surveyed leafhoppers on grassland sites in the Gallatin Valley of Montana. We sampled 12 sites representing two habitat types defined by their dominant plant species in an undisturbed state. We found at least 66 species of leafhoppers among the 44,428 adults collected; seven groups comprised 83% of all individuals collected. Sites with similar vegetation had broadly similar leafhopper assemblages, and assemblages differed most between the drier sites dominated by the grasses needle-and-thread / blue grama versus the wetter sites dominated by the grass smooth brome. The patterns of species distribution that we observed suggest that many leafhoppers are specialists on individual plant species. In fact, variation in abundance of some of the most common leafhopper taxa on our sites was correlated with the percent cover of their known host plants. Our analyses of the leafhopper assemblages generally support the contention that terrestrial plant associations are among the more useful indicators of insect community composition. Technical Abstract: Using sweep samples, we surveyed leafhoppers (Homoptera : Cicadellidae) on grassland sites in the Gallatin Valley of Montana during 1988 and 1991. We sampled 12 sites representing two habitat types defined by their dominant plant species in an undisturbed state (Stipa comata / Bouteloua gracilis and Festuca idahoensis / Agropyron spicatum). At half of the sites, the native plant communities were present, whereas the remainder had been reseeded with either Agropyron spicatum (to replace the S. comata / B. gracilis assemblage) or Bromus inermis (to replace the F. idahoensis / A. spicatum assemblage). We found at least 66 species of leafhoppers among the 44,428 adults collected. Seven taxa comprised 83% of all individuals collected: Doratura stylata (26%), Ceratagallia spp. (18%), Endria inimica (17%), Orocastus perpusillus (7%), Sorhoanus spp. (6%), Athysanella spp. (5%), and Psammotettix lividellus (4%). Sites with similar vegetation had broadly similar leafhopper assemblages, and assemblages differed most between the relatively xeric Stipa comata / Bouteloua gracilis sites and the more mesic sites dominated by Bromus inermis. The composition of a leafhopper assemblage at a site tended to be more similar to those on non-contiguous sites with the same overall vegetation than to those on contiguous sites with different vegetation. These patterns are likely related to the fact that many Cicadellidae are host specialists. In fact, variation in abundance of some of the most common leafhopper taxa on our sites was correlated with the percent cover of their known host plants. Our analyses of the leafhopper assemblages generally support the contention that terrestrial plant associations are among the more useful indicators of insect community composition. |