SPECIES COMPOSITION, PHENOLOGY, AND POSSIBLE ORIGINS OF LEAFHOPPERS (CICADELLIDAE) IN OHIO VEGETABLE CROPS

Leafhopper populations were sampled with sweep nets in grain cover and vegetable crops during 1988 and 1989. Populations in vegetable crops consisted primarily of aster leafhopper, Macrosteles quadrilineatus Forbes, except for potato crops in which Empoasca spp. were common. Adult aster leafhoppers were caught several weeks before nymphs in each year. Peak catches of aster leafhopper adults and nymphs occurred in both June and july. Data were consistent with the hypothesis that aster leafhoppers migrate to Ohio vegetable-growing areas in late May and June. Air trajectory analysis indicated three possible source areas of M. quadrilineatus migrating into Ohio vegetable-production areas: Arkansas, Louisiana, Texas, and Oklahoma; western Ohio, Indiana, and Illinois; and a corridor extending from Ohio to the Dakotas. Bioassays for aster yellows during 1989 and 1990 indicated that the leafhopper populations present during those years contained very few inoculative individuals. Growers should base treatment decisions on monitoring for inoculative aster leafhoppers.