Grapevine red blotch virus (GRBV) currently poses a serious threat to the wine industry. The three-cornered alfalfa hopper (3CAH), Spissistilus festinus (Say) (Hemiptera: Membracidae), was recently shown in a greenhouse study to be a vector of GRBV in grapes. Feeding and reproductive status of 10 weed and 10 cover crop species commonly found in grape vineyards were evaluated in no-choice tests. Species confirmed as reproductive hosts were subsequently evaluated in choice tests to determine S. festinus oviposition preference. Spanish clover, dandelion, birdsfoot trefoil, common groundsel, field bindweed, magnus peas, bell beans, blando brome, purple vetch, black medick, subterranean clover, crimson clover, and woollypod vetch were all found to be reproductive hosts. The plant species that exhibited the greatest nymph emergence in each of the three groups tested for preference were all in the family Fabaceae. Knowledge of plant species present in vineyards that serve as alternative hosts for S. festinus can contribute to developing management strategies to mitigate virus spread.

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Feeding by the three-cornered alfalfa hopper, Spissistilus festinus (Say) (Hemiptera: Membracidae) results in girdling of grapevine petioles and shoots. Its significance as an economic pest of grape has increased since it was shown to transmit Grapevine red blotch virus (GRBV) in a greenhouse study. However, the status of grapevines as a reproductive host for S. festinus remained undetermined. Adult S. festinus were caged onto three regions of the grapevines: apical shoot, green shoot, and dormant cane. Their ability to reproduce was determined by weekly destructive sampling for 7 wk. Successful oviposition and nymphal emergence were observed on apical and green shoots, but not on dormant canes. However, insect development beyond the second nymphal instar did not occur. Knowledge of S. festinus reproduction on grapevines will be an important consideration in designing management guidelines to minimize the spread of GRBV in vineyards.

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