Progress report for LNE25-494R
Project Information
Project focus:
This project will benefit grape growers, winery owners, and associated industry partners whose businesses are being negatively impacted by spotted lanternfly (SLF). SLF is an invasive, sap-feeding insect introduced into the U.S. from Asia that has become an economically devastating pest of vineyards. Grape growers with SLF-infested vineyards have reported significant yield losses along with a reduction in wine quality, vine decline, and vine death due to extensive SLF feeding. High SLF population pressure has forced grape growers to dramatically increase the number of insecticide applications throughout the growing season. As a result, SLF management has significantly increased the production costs for many vineyards. Therefore, research leading to improve SLF management and reduced insecticide use is essential for the grape and wine industry.
Solution and approach:
Our proposal aims to test an agroecological approach using toxic milkweeds planted along vineyard borders as a trap to kill SLF. After several anecdotal reports of SLF dying at the base of milkweed plants, we tested common milkweed (Asclepias syriaca) and found that it kills 60-80% of SLF nymphs and adults within 24 hours, even when grapevines are present as a food source. This proposal aims to 1) document SLF mortality when feeding on different species of milkweed that exhibit varying levels of toxicity, and 2) test the efficacy of milkweed planted in vineyard borders in reducing SLF populations. We will quantify the mortality of SLF adults enclosed in mesh cages with one of the following three milkweed species: Asclepias tuberosa, Asclepias syriaca, and Asclepias incarnata, which have low, medium, and high cardenolide (cardiac glycoside) content, respectively. At the same time, we will quantity SLF mortality when provided Riesling grapevines (control plants) and Riesling plus each of the above milkweed species. These experiments will allow us to select the milkweed species for testing in the field. We will plant the selected milkweed species in vineyard borders and quantify the SLF infestation levels from August to November for two consecutive years. Our results will provide new knowledge on the efficacy of milkweed as a novel method for SLF control in vineyards. Farmers will be reached and engaged through in-person and online extension meetings that will be co-organized by the project team for the duration of the project.
The goals of this project are (1) to quantify the mortality of spotted lanternflies when feeding on different species of milkweed that exhibit varying levels of toxicity to insects, and (2) to test the efficacy of milkweed plantings in reducing spotted lanternfly populations in vineyards. This research will generate knowledge of alternative strategies for spotted lanternfly control in the northeast US. If proven effective, growers will have a new, sustainable, and eco-friendly strategy to help alleviate the devastating effects of spotted lanternfly. Importantly, this method of pest management has the potential to reduce the use of toxic and costly pesticides.
The spotted lanternfly (SLF) is an invasive species in the U.S. that has become an economically devastating pest of vineyards and other crops (Urban 2020). Feeding by this insect reduces grapevine yield after the second year of consecutive infestation and reduces juice sugars and wine total phenolics and tannins within a single season, which decreases beverage quality (Harner et al., 2022; Acevedo et al., unpublished). Extensive SLF feeding over consecutive seasons reduces plant starch reserves, leading to grapevine death (Harner et al., 2022). In response, grape growers have had to increase the number of insecticide applications to control these insects. SLF adults are particularly destructive due to their ability to remove large amounts of plant sap to fulfill their nutritional requirements. The adults continuously infest vineyards from the surrounding vegetation in late summer/early fall, and single insecticide applications only control the population present at the time of application; therefore, numerous insecticide sprays are needed from August to November. The need for insecticide applications coincides with grape harvest and continues until the freezing temperatures kill the adults, which often occurs in November in Pennsylvania. Results from a grower's survey conducted in 2022 revealed a 2-6-fold increase in insecticide sprays for SLF control (Schmidt, unpublished). The additional sprays increase costs, reduce profit, and enhance environmental and human health risks associated with pesticide use. Grape growers and wineries have also reported growing consumer concerns about the increasing use of pesticides. Therefore, alternative solutions to improve SLF management are essential for the grape and wine industry.
Grape growers have expressed their urgent need for effective, inexpensive, sustainable, and environmentally friendly strategies to control SLF. The project leader has first-hand knowledge of this need through direct contact with farmers as part of her extension activities. Farmers are eager to explore alternative options for SLF control, even those that involve modification of their farm landscape, which has been demonstrated by their efforts to eliminate tree of heaven, a key host plant for SLF. This project will explore a promising, low-cost method for SLF control by planting milkweed along vineyard perimeters to serve as living traps to kill SLF as they feed on these toxic plants. This novel approach will benefit over 1,600 growers in the northeastern U.S. This estimated number of grape growers comes from the number of wineries (1,361) reported in a Wine Business article in February of 2024 (https://www.winebusiness.com/wbm/article/282423) plus our extension listserv from the Lake Erie Grape Region (PA and NY) of 273 juice grape growers.
This project aligns perfectly with the SARE's outcome statement of promoting profitable, sustainable, resilient, and economically viable agriculture in the northeastern U.S. The novel and inexpensive approach to SLF control proposed here will facilitate adoption by a wide range of farmer groups, including those who may not be able to afford expensive insecticides and the equipment needed for their application. Therefore, this project also empowers farmers and their employees with knowledge to effectively steward resources and promote sustainable practices.
Goal setting and decision-making within our program are guided by the land-grant mission of integrating research, extension, and education to address stakeholder-identified needs. Project goals are developed collaboratively through ongoing engagement with specialty crop growers, extension educators, industry partners, and researchers, ensuring that priorities reflect real-world challenges faced by agricultural communities in the Northeast. Decisions related to research direction, outreach activities, and evaluation metrics are informed by grower feedback obtained through meetings, workshops, surveys, and on-farm interactions. Centering and belonging are fostered by valuing growers and community partners as co-creators of knowledge rather than end users, creating spaces for open dialogue, shared learning, and mutual respect. This approach empowers diverse stakeholders by incorporating their experiences and perspectives into project design, implementation, and dissemination, ultimately promoting inclusive participation and increasing the relevance, adoption, and impact of project outcomes.
Research
Methods for objective 1: “To quantify the mortality of spotted lanternflies (SLF) when feeding on different species of milkweed that exhibit varying levels of toxicity to insects.”
We grew three different milkweed species that are native to the northeast U.S. and differ in their concentration of cardenolides, which are generally toxic to herbivorous insects. These species and their relative cardenolide content include Asclepias tuberosa (low), Asclepias syriaca (intermediate), and Asclepias incarnata (high). Seeds from these species were obtained from Co-PI S. Hermann, who collected them from her garden and were germinated by shaking the seeds with sand moistened with distilled water and then chilling them at 4˚C for 3 weeks. Seeds were then separated from the sand and placed into Ziploc bags with a paper towel moistened with distilled water and placed in a dark container for 2 days. Those that germinated (approximately 80% of the A. syriaca and A. tuberosa seeds and 60% of the A. incarnata seeds) were then moved to 4-inch pots in potting soil (Promix) and grown under greenhouse conditions with up-potting occurring until they were large enough to go in 3-gallon pots at Penn State University (PSU). The plants were used for experiments when they were at least 2 months old and at least 8 inches tall. We tested the mortality of SLF when provided no host plants, either milkweed or grapevines (Vitis vinifera), and when provided both grapevines and milkweed in 24”x24”x36” pop-up cages. We used potted grapevines of the cultivar Riesling as our control based on previous experiments that demonstrated high SLF survival when feeding on this cultivar (Elsensohn et al., 2023). Thus, we tested the following treatments (T) on SLF mortality:
T1: SLF individuals feeding on Asclepias tuberosa
T2: SLF individuals feeding on Asclepias tuberosa and Riesling grapevines
T3: SLF individuals feeding on Asclepias syriaca
T4: SLF individuals feeding on Asclepias syriaca and Riesling grapevines
T5: SLF individuals feeding on Asclepias incarnata
T6: SLF individuals feeding on Asclepias incarnata and Riesling grapevines
T7: SLF individuals feeding on Riesling grapevines (control)
T8: SLF individuals not provided with a host plant (starvation control).
Plants from each treatment were placed in mesh pop-up cages, and each cage was infested with 3 SLF. Insect mortality and feeding were assessed at 1, 2, 4, 6, and 24 h. Evidence of feeding was based on the production of honeydew by SLF, which is abundant and easy to see, as well as observation of the SLF inserting their stylets into the plant. SLF were collected from wild conditions on the PSU campus, which is within the SLF quarantine zone in Pennsylvania, and taken to the greenhouse for the experiments. We tested all nymphal instars and adults, and there were 7 replications per treatment. Experiments with adults were begun on September 24th, 2025, when the majority of the lanternflies in the field had developed to this life stage. In addition to the visual checks, adults were marked with fluorescent powders to allow us to identify individuals: one marked with yellow (Bioquip #1162Y), one marked with blue (Dayglo Corp. ECO19 Horizon Blue), and one marked with green (Dayglo Corp. ECO18 Signal Green) placed into each pop-up, including the grape and starvation treatments. SLF were photographed once per minute with IR camera modules attached to Raspberry Pi computers, with review of the photos ongoing. Differences in cardenolide concentration for each milkweed species and in the bodies of the dead SLF are being confirmed using High-Performance Liquid Chromatography (HPLC) with synthetic standards at PSU using methods developed by our collaborator Anurag Agrawal from Cornell University (Petschenka et al., 2023).
Experimental design: The above treatments were tested using a complete randomized design where SLF individuals were randomly assigned to each of the treatments. The experimental unit consisted of one cage with the respective plant treatments and 7 SLF. Data on SLF mortality after 24 hours between treatments were analyzed using a Kruskal-Wallis test followed by a Dunn’s post hoc test, and cardenolide concentration relative to mortality will be analyzed using logistic regression under the Generalized Linear Model (GLM) framework using the software R. We also used Fisher’s exact tests to compare SLF feeding preferences between milkweed and grape during our checks.
We found that first instar spotted lanternfly mortality after 24 hours varied significantly between our milkweed, grape, and starvation treatments (χ2 = 23.43, df = 7, p = 0.001), with mortality on A. incarnata and A. syriaca alone being significantly higher than that in the grape alone and starvation treatments (Figure 1A). Second instars also experienced significantly different mortality between treatments after 24 hours (χ2 = 25.94, df = 7, p < 0.001), with significantly higher mortality in the A. incarnata, A. incarnata choice, A. syriaca, and A. tuberosa treatments than in grape alone or starvation control (Figure 1B). There was also a significant difference in mortality between treatments after 24 hours in the third instar spotted lanternflies (χ2 = 41.73, df = 7, p < 0.001), with mortality in the A. incarnata, A. syriaca, and A. tuberosa alone treatments being significantly higher than that in the grape alone and starvation control (Figure 1C). Fourth instars also showed a significant difference in mortality after 24 hours among treatments (χ2 = 28.44, df = 7, p < 0.001), with significantly higher mortality in the A. incarnata, A. syriaca, and A. tuberosa treatments relative to the grape alone and starvation treatments (Figure 1D). Adults similarly showed a significant difference in mortality after 24 hours between treatments (χ2 = 32.647, df = 7, p < 0.001), with A. syriaca and A. tuberosa mortality being higher than the starvation treatment, and A. incarnata, A. syriaca, A. syriaca choice, A. tuberosa, and A. tuberosa choice having significantly higher mortality than the grape alone treatment (Figure 1E).
At the earlier time checks, there was a significant difference in mortality at the 1-hour check for 1st instar SLF (χ2 = 19.426, df = 7, p = 0.007), with mortality in A. syriaca being significantly higher than the other treatments (Figure 2A). There was also a significant difference in mortality at the 6-hour time checks for 2nd instars (χ2 = 14.823, df = 7, p-value = 0.03834) and 4th instars (χ2 = 15.457, df = 7, p-value = 0.03057). For 2nd instars at the 6-hour check, A. tuberosa had significantly higher mortality than the grape and starvation treatments, while A. syriaca and A. syriaca choice had significantly higher mortality than the starvation treatment (Figure 2B). For 4th instars, at the 6-hour check, A. syriaca had significantly higher mortality than the grape and starvation treatments (Figure 2C).
When comparing host plant preferences in the treatments with both grape and milkweed (choice treatments), we found no significant preference between milkweed and grape in 25 out of 72 checks; thus, there was a significant preference for grape in the other 47 observations. Of the 25 checks where there was no preference between milkweed and grape, 10 were between A. syriaca and grape, 10 were between A. tuberosa and grape, and 5 were between A. incarnata and grape. It is also interesting to note that, while many of the treatments in spotted lanternflies were provided which both grape and milkweed were at the same time did not result in significantly higher mortality than the grape alone treatment, but there was still mortality, which, until the adult life stage, did not occur in the grape treatment at all. This suggests that, even in the presence of grape, some lanternflies likely fed on the milkweed when we were not watching and died, which is confirmed by the photos of the adults from our IR cameras.
Our results suggest that the three milkweed species tested in this study can cause mortality in spotted lanternfly across their life cycle. In all life stages except the first instar, there was significantly higher mortality in spotted lanternfly fed on all 3 species of milkweed relative to those fed on grape alone. It is possible that we did not see significant mortality in first instars on A. tuberosa due to a lack of feeding, as we did not see a significant difference between the starvation and grape treatment at any life stage, suggesting that spotted lanternfly nymphs could survive by not feeding on the milkweed at all. For the first instar SLF on A. tuberosa in particular, it is worth noting that the stems of A. tuberosa are covered in trichomes that could have deterred the first instars from feeding, as they were not yet large enough to get through these defenses very effectively.
We would recommend the use of A. syriaca for field testing. A. syriaca and A. tuberosa resulted in the most checks, with no preference between host grape and milkweed plants, suggesting they could be fed on in the field when other hosts are available. Of these two species, treatments with A. syriaca resulted in higher mortality than treatments with A. tuberosa (choice or no choice treatments) in 8 out of 10 instances. Because of this, and the relative ease of growing A. syriaca compared to the other species, this species is a good option to test in the field.
Our results suggest that the three milkweed species tested in this study can induce spotted lanternfly mortality in greenhouse conditions, but higher mortality rates were found with A. syriaca.
Education & outreach activities and participation summary
Educational activities:
Participation summary:
-In-person talk given by Anne Johnson (Postdoctoral scholar associated with this project): “Development of integrated pest management strategies of spotted lanternfly”. Extension presentation on new developments in cultural and biological controls of spotted lanternflies from research at the Eastern New York Spotted Lanternfly Workshop. ~50 attendees, including researchers, Extension agents, growers, and members of the general public affected by spotted lanternfly. February 4, 2025, Marlboro, NY.
-In-person talk given by Anne Johnson (Postdoctoral scholar associated with this project) : Johnson, A., Palau, M., Mucciolo, S. M., Germeroth, L., Acevedo, F., Hermann, S., Hoover, K. (November 2025). Interactions of spotted lanternfly with milkweed. Presentation given at the Entomological Society of America National Meeting, Portland, OR. ~44 attendees, primarily consisting of members of ESA.
-Online talk given by Anne Johnson (Postdoctoral scholar associated with this project): “Allies Against an Invasive: Interactions Between Spotted Lanternflies and Native Species” Seminar given as part of the Cornell IPM Academic Seminar Series. 94 attendees at the time of the webinar, and the recording available at https://www.youtube.com/watch?v=2mjh6O3yblc currently has 58 views, with attendees including academics, Extension agents, growers, and members of the general public. November 19, 2025, online.