| Summary: | Mealybugs cause economic loss to vineyards through physical damage, fouling fruit and leaves with honeydew, and the transmission of viruses. <i>Planococcus ficus</i> is one of several mealybug species in vineyards, and one that causes economic damage over a relatively large global range. To develop novel management tools, host resistance to <i>P. ficus</i>, which has not previously been identified for any grape cultivars, was studied. Ten grape lines (species, cultivars, and rootstocks) were evaluated for <i>P. ficus</i> resistance across two separate potted plant assays. Significant differences were detected among cultivars and rootstocks in the recorded number of <i>P. ficus</i> juveniles, adults, and egg sacs. Cabernet Sauvignon and Chardonnay were two of the most favorable grape cultivars for mealybug population growth, whereas rootstocks IAC 572, 10-17A, and RS-3 all demonstrated some level of resistance. Southern fire ant (<i>Solenopsis xyloni</i>) was positively associated with mealybug populations, but did not have a negative effect on the observed presence of other arthropod species including potential predators.
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