Spotted Lanternfly Feeding Induces Systemic Defense Responses in Grapevines

The spotted lanternfly (Lycorma delicatula), an invasive planthopper in the United States, threatens vineyards by reducing yield and compromising plant health, yet grapevine immune responses to its feeding remain poorly understood. This study evaluated systemic grapevine responses to spotted lanternfly feeding under varying insect densities and feeding durations. Potted Vitis vinifera cultivar Cabernet Franc vines were infested with 0, 5, 10, or 15 adults per vine for 1, 3, 5, 7, 14, 21, or 29 days, using separate plants at each time point. Leaf tissue was analyzed for chlorophyll content, polyphenol oxidase (PPO) and peroxidase (POX) activity, protein content, total phenolics, and condensed tannins. Bioassays assessed spotted lanternfly survival and weight gain on previously infested plants. Chlorophyll content declined after 21-29 days in vines infested with 15 insects. PPO activity increased throughout the experiment (except on day 7) under infestations of 10-15 insects, whereas POX activity rose after 7 days but declined after 29 days of feeding. Leaf protein content increased in vines infested with 15 insects after 7 and 29 days, and phenolic concentrations increased consistently from 7 to 29 days in vines infested with 10-15 insects. Condensed tannin concentrations were unaffected by density treatments. Bioassays showed reduced survival and weight gain of lanternflies when fed on vines previously infested with 15 insects for 29 days. Collectively, these results suggest that prolonged, high-density spotted lanternfly feeding induces coordinated, time- and density-dependent systemic grapevine defenses associated with reduced host suitability. Future studies should identify the mechanisms underlying these responses and their persistence across grapevine cultivars.