Rangeland Grasshoppers (Orthoptera: Acrididae) Associated with Mesquite and Juniper Habitats in the Texas Rolling Plains

Density, species composition, and spatial distribution of grasshoppers and biomass and species composition of herbaceous plants in 2 rangeland habitats, honey mesquite, Prosopis glandulosa Torrey, and redberry juniper, Juniperus pinchoti Sudworth, were quantified in the Texas Rolling Plains in 1992 and 1993. Grasshoppers were sampled weekly from early May to late September, and vegetation was sampled 3 times (May, July, and September). Grasshopper density was significantly greater in the mesquite habitat than in the juniper habitat for both years, with an average of 6.38 and 5.50 grasshoppers per square meter in mesquite habitat and 0.86 and 0.33 grasshoppers per square meter in juniper habitat in 1992 and 1993, respectively. Grasshopper species composition varied with sampling year and with the habitat, with significantly greater species diversity in mesquite habitat compared with that in the juniper habitat. Of the 37 species of grasshoppers captured during the 2-yr study, 3 species in the mesquite habitat, Hesperotettix speciosus (Scudder), Hesperotettix viridis (Thomas), and Syrbula admirabilis Uhler, and 2 species in the juniper habitat, Ageneotettix deorum (Scudder) and S. admirabilis , comprised ≍50% of the adult grasshoppers collected. Analysis of dispersion patterns of grasshoppers in 1-m2 transects showed that the grasshoppers exhibit a random spatial pattern in both habitats. Average herbaceous biomass for both years was greater in the mesquite (mean = 3,435 kg/h) than in the juniper (mean = 793 kg/h) habitat, with greater grass than forb biomass in both habitats. Grasshopper abundance and species composition in rangeland mesquite and juniper habitats appear to be related with the herbaceous plant community structure in those habitats.