POPULATION-DENSITY OF EMPOASCA-FABAE (HOMOPTERA, CICADELLIDAE) IN WEEDY BEANS

The response of Empoasca fabae (Harris) to beans, Phaseolus vulgaris L., in four weed habitats, bean monocultures, beans with Brassica kaber (D.-C.), beans with weeds that were removed in early July, and unweeded beans, was examined by visual and D-Vac samples. Weeds in the unweeded treatment were mixed broadleaf and grassy weeds. Visual samples showed that leafhopper density per bean leaflet was highest in bean monocultures, lowest in unweeded beans, and intermediate in the remaining weed habitats. D-Vac samples showed no difference in leafhopper density per area among weed habitats. D-Vac samples included leafhoppers living on the associated weeds, whereas visual samples restricted population estimates to leafhoppers on bean plants. These results suggest that mixed broad leaf and grassy weeds did not affect total E. fabae population density per land area, but did affect the spatial distribution of E. fabae among weedy and cultivated host plants.