Progress 11/09/18 to 09/30/20
Outputs
Target Audience:Target audiences include the PA Departmentof Agriculture, USDA Animal and Plant Health Inspection Service (APHIS), and pest managers in the nursery, landscape and forestry industries. This work will also contribute to new knowledge for other scientists, Extension educators, and the general public.The remote sensing study will be of use to a wide audience including other researchers, regulatory and agency staff, and homeowners and agricultural producers. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?These projectsinvolved sevenundergraduate students, including two drone pilots.A grad student and two postdocs received training in operation of the equipment used for physiological measurements. All personnel obtained extensive experience in how to work with spotted lanternfly in the quarantine area. The graduate student is presenting the results of her research on this project at the Virtual Entomological Society of America this fall. How have the results been disseminated to communities of interest?Several presentations were made by the PIs to other SLF researchers, personnel from Pennsylvania Department of Agriculture (PDA) and USDA Animal and Plant Health Inspection Service (APHIS), and other stakeholders such as legislative staff, forestry and ornamentals extension educators, and the nursery and forest products industries. Results were also disseminated at the USDA Specialty Crop and Research Initiative (SCRI) Working Group meeting, at the Forest Health Briefing organized by Penn State University, and conveyed at weekly Communications meetings to extension educators taskedwith SLF education. Remote sensingpersonnel provided informal briefings at the PA Private Forest Landowners meeting. What do you plan to do during the next reporting period to accomplish the goals?We intend to continue working on physiological responses of common hardwood trees at the common garden with funding from the USDA APHIS Farm Bill. Carbohydrate samples for all experiments are being processed and we will also conduct nutrient analyses and metabolomics for plant chemical defenses. We are also planning to conduct sap flux analysis to compare sap flow pressure betweenAilanthusand silver maple since both appear to be able to tolerate a fair amount of SLF adult feeding pressure. Results of these continued efforts will be reported under the appropriate active AES project.
Impacts
What was accomplished under these goals?
Objective 1(Miller & Hoover):During the summer of 2020 the Mobile Geospatial Systems Group collected visible and near-infrared imagery over pre-designated ground sampling locations where tree and insect observations were being made by our collaborators.Visible and near-infrared imagery were collected at Blue Marsh Lake and the common garden established by lead PI Hoover in 2019 before and after insect damage occurred. At Blue Marsh, sixfield sites were imaged six times from before treatment with Safari orBeauvaria bassianaapplied from the ground or air, and three times over the common garden before and after SLF were released on trees. These data are being processed currently. Objective 2(Hoover): In year onewe did two experiments to determine the impact of SLF pressure on tree health.We set up a study with planted trees in Berks County to determine if SLF feeding impacted tree health when SLF were given a choice of host trees to feed on and a more controlled study at a common garden, also in Berks County. For the first study,we planted ten plots of threedifferent preferred host tree species for SLF in fall 2018:one each of willow, silver maple, and black walnut. In five of the plots we also planted one tree-of-heaven, while in the other five river birch wereplanted.In May 2019, full enclosures were placed over each plot and we released 355 first instar SLF in each enclosure. Prior to releasing SLF and in early August, parameters of tree physiology were measured, includingphotosynthesis, transpiration, and stomatal conductance. Also, two stems per tree were removed for carbohydrate analysis. Tree species responded differently to SLF feeding. For example, glucose concentration and photosynthesis for silver maple declined with increasing pressure. In contrast, glucose concentration increased for willow with increasing pressure, but photosynthesis declined. In June 2020, we repeated this study on the same trees, which by the next year, were larger. We found that river birch had the highest photosynthetic rate followed byAilanthus, willow and silver maple. In river birch, increasing SLF pressure suppressed gas exchange and at the highest level of pressure, photosynthesis was suppressed. In contrast, increasing SLF numbers enhanced gas exchange in willow by 50% at the highest level of SLF pressure. However, photosynthesis of silver maple andAilanthuswas unaffected by SLF pressure. Water use efficiency was suppressed for all species with increasing SLF density. In July and August, we did not detect measurable effects of SLF feeding on gas exchange and water use efficiency. These differences suggest that some species may rely on different physiological mechanisms to tolerate SLF feeding and there appears to be compensation at low and moderate densities. The second controlled experiment was done on individual silver and red maple trees at a common garden that we established in May 2019. We planted over 800 trees in a split plot randomized block design of red and silver maple, tree-of-heaven and black walnut. To determine how feeding pressure impacts the health of maple trees, two sets of experiments were conducted, first using fourthinstar nymphs, followed by a study using adult SLF at high density.In July 2019, three densities of fourthinstar nymphs were introduced into sleeve cages that were placed over vigorous branches of red and silver maple trees (these were the largest trees in the first year). Eleven days of feeding did not affect the rate of photosynthesis for red maple, but silver maple was marginally affected by nymph feeding. Moderate SLF density marginally enhanced photosynthesis on the final day of the experiment for silver maple. Stomatal conductance was not different between treatments for either maple species but was instead reduced by the sleeve cage. In 2020 we repeated this study but this time wefully enclosed trees with mesh rather than using individual branches and released fourth instar nymphs at four different density levels (0-120 nymphs) on silver maple and black walnut. In contrast to 2019, pest pressure of fourthinstars had no effect on leaf gas exchange (photosynthesis, stomatal conductance and transpiration) of silver maple or black walnut, indicating that when nymphs are able to control where they feed, trees are less affected. To address the impact of adult SLF pressure, in 2019 adults were collected and two sleeve cages were placed over different healthy branches on red and silver maple; 40 adult SLF were added to one of the sleeve cages on each tree and the other was left empty as a control.An additional branch without a sleeve cage was flagged for subsequent measurements to determine if the sleeve cage affected tree measurements.In contrast to nymph feeding, adults suppressed photosynthesis for both red and silver maple by day three and remained low for the duration of the experiment. In 2020 we investigated the effects of adult SLF using whole tree enclosures over silver maple andAilanthus. Leaf gas exchange was measured every three-fourdays. In August, adult feeding at four different densities showed leaf gas exchange was gradually suppressed over time in silver maple andAilanthus. At 20 days of feeding, photosynthesis ofAilanthuswas suppressed by about 30%, 74% and 25% at light, moderate and heavy infestation levels compared to controls. For silver maple, moderate and heavy SLF infestation suppressed photosynthesis while light pressure had no effect. After 20 days, transpiration forAilanthuswas suppressed for trees with moderate infestation, but trees with light and heavy infestations had similar transpiration rates to the control. For silver maple, transpiration was suppressed for trees with moderate and heavy infestation, while transpiration for trees with light pressure was similar to the control. ForAilanthus, water use efficiency was not affected by SLF feeding, but for silver maple, water use efficiency was 2X higher for trees with moderate infestation than all other treatments. Implications: at the whole-tree level, the effect of nymph feeding may be minimal at SLF densities of 120 nymphs per 6-foot tall tree; however, adult feeding altered tree physiology by shifting gas exchange in response to increasing adult density levels.Silver maple is able to continue to photosynthesize even while transpiration is declining so they are using their water more efficiently and are able to maintain some level of photosynthetic productivity with moderate SLF infestation.The observed difference in trunk access compared with access to just one branch may have allowed trees to support higher SLF densities over a longer period.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Uyi, Osariyekemwen, J. Keller, A. Johnson, D. Long, B. Walsh, and K. Hoover. 2020. Spotted lanternfly can complete development and oviposit without access to the preferred host, Ailanthus altissima. Environ. Entomol. DOI:10.1093/ee/nvaa083.
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Progress 11/09/18 to 09/30/19
Outputs
Target Audience:The information on SLF impacts on tree species that are important for forests will be of great benefit to departments of agriculture, USDA, landscape and forest managers, and production nurseries. The remote sensing work being done on this project will be of use to a wide audience including other researchers, regulatory and agency staff, foresters, and homeowners and agricultural producers. Changes/Problems:As noted above, our research plan strategy of using UAS-based remote sensing to monitor SLF at sites noted to have had SLF in previous years failed to account for the random movement of the insect from year-to-year. Our overall goal was to measure the effect of the insect on tree health by coordinating airborne observations with ground-based observations of individual tree status. Clearly, the lack of our ability to control for the elusive nature of the pest makes this strategy difficult if not impossible. As an alternative, we are considering a strategy to monitor the common garden, which is populated with important timber species, where experiments are being conducted in a controlled environment with different densities of SLF pressure. We would image the common garden trees, prior to and then after insect feeding, and then in regular intervals until leaf senescence to visualize the level of damage. The trees in the common garden can also be used to measure photosynthesis rate, transpiration, carbohydrate levels, nitrogen, chlorophyll, etc., so we hope to link these measurements with subtle to more intense symptoms that can be picked up with imaging. What opportunities for training and professional development has the project provided?Our work involved two undergraduate students, Philip Walsh and Hugh Walton. Philip is a trained and experienced FAA Section 107 and PSU Approved UAS Pilot who will graduate in December, 2019 and move to a position with AmeriCorps flying UAS missions for FEMA. Hugh is a sophomore undergraduate in aerospace engineering who is currently in training to be a PSU-approved UAS pilot. A grad student and two postdocs received training in operation of the equipment used for physiological measurements. All personnel obtained extensive experience in how to work with spotted lanternfly in the quarantine area and took online training on how to ensure SLF are not transported from quarantined counties to non-quarantined regions. How have the results been disseminated to communities of interest?Several presentations were made by the PIs to other SLF researchers, personnel from PDA and USDA APHIS, and other stakeholders such as legislative staff, forestry and ornamentals extension educators, and the nursery production industry. Remote sensing personnel provided informal briefings at the PA Private Forest Landowners meeting (March, 2019) and at the California Grange regular monthly meeting in Montour County (July, 2019). PI Hoover will present results from this project next month at the Entomological Society of America annaul meeting in a special symposium she co-organized on SLF. What do you plan to do during the next reporting period to accomplish the goals?In Spring 2020, we will count the number of eggs that hatch from each egg mass laid in the multi-tree enclosures and determine if any of the physiological measurements taken during the previous season are predictive of reproductive success. Because the trees used in this study were not as large as they may need to be for SLF to sexually mature without tree-of-heaven, we will repeat this study next season when the trees are larger. We also plan to add 2 control enclosures using the same tree species groupings without SLF to compare physiological measurements between treatments and controls. At the common garden, we will examine the impacts of 3 different densities of SLF 4th instar nymphs and adults on physiology of four tree species at the common garden: black walnut, red maple, silver maple, and tree-of-heaven in well replicated experiments. We will compare sugar metabolism among species to determine if there are any cues to why tree-of-heaven is a preferred host.
Impacts
What was accomplished under these goals?
Objective 1: The Mobile Geospatial Systems Group collected visible and near-infrared imagery over the pre-designated ground sampling locations where tree and insect observations were being made by our collaborators. These test locations were noted for their prior infestations of SLF but did not have infestations this summer. Flights at 2 sites at the Musser Gap Scout Reservation were suspended due to hazardous power line conditions. Objective 2: We did two different controlled experiments to determine the impact of SLF pressure on tree health. We set up a controlled study with planted trees in Berks County to determine if SLF feeding impacted tree health when SLF were given a choice of host trees to feed on. To do this, in Sept. 2018, we planted 10 plots of 4 different preferred host tree species for SLF: one each of willow, silver maple, black walnut, and river birch. In half of the plots we also planted one tree-of-heaven, while an additional silver maple was planted in the other half of the plots. There are 5 replicates of each treatment (with and without tree-of-heaven)for a total of 10 plots. In May 2019, full enclosures were placed over each plot tall enough to allow trees to reach a height of 12 feet. In each enclosure, we released 355 first instar SLF. Every week we recorded survival, the number of each life stage on each tree species, and tree health. The number of egg masses laid in each enclosure on different hosts was also recorded. At the beginning of the study and in early August, parameters of tree physiology were measured, including photosynthesis rate, transpiration, carbohydrates and stomatal conductance. Photosynthesis, transpiration and stomatal conductance were measured on one leaf per tree from 09h00 to 13h00 under saturating light conditions (1500 µmol m-2s-1) using a LI-6400 Photosynthesis System (LI-COR, Lincoln, NE). Measurements were taken on Aug 1 and September 25, 2019. On the day physiological measurements were taken, one branch per tree was also sampled for carbohydrate analysis. Branch samples were flash frozen and transported to the laboratory. Branch samples were freeze dried and separated into bark and wood tissue. Samples were ground with a Wiley Mill fitted with a 2mm screen. Nonstructural-carbohydrate concentrations were determined using modified procedures from Nelson (1944) and Somogyi (1952). In the future, GC-MS and LC-MS will be used to target other common phloem sugars such as fructose and sucrose and secondary metabolites to further characterize species differences. Data analysis: Carbohydrate and photosynthesis data were analyzed using a mixed model with Proc Glimmix in SAS 9.4 (SAS Institute Inc.; Cary, North Carolina). Tree species was a categorical variable and the total number of SLF found in a cage was used as a regressor variable at each measurement date. For carbohydrate concentration, a multiple comparison was also conducted on least squares means across species using the slice/diff option in Proc Glimmix. Survival from nymph to adult did not differ between the two treatments (with and without tree-of-heaven), except that development from one life stage to the next was slightly slower without tree-of-heaven. As of Oct. 28, there were 21 egg masses produced in the 3/5 enclosures with tree-of-heaven, but none in the enclosures without it. Tree species responded differently to SLF feeding (P<0.01). For example, glucose concentration and photosynthesis for silver maple declined with increasing SLF number. In contrast, glucose concentration increased for willow with increasing SLF number, but photosynthesis declined. These differences in glucose concentration and photosynthesis suggest that some species may rely on different physiological mechanisms to tolerate SLF feeding. Tree species differed in carbohydrate concentration of bark (with phloem tissue) for both glucose and starch (P<0.01). Black walnut had the highest glucose concentration followed by tree-of-heaven and river birch. Silver maple and weeping willow had the lowest glucose concentrations. Weeping willow had a higher starch concentration in bark tissue than all other species. It should be noted that starch concentration of tree-of-heaven was undetectable with this analysis. Future analyses will target other common phloem sugars such as fructose and sucrose and secondary metabolites using GC-MS and LC-MS, respectively, to further characterize species differences. The second controlled experiment was done on individual silver and red maple trees at a common garden in Berks County that we established in May 2019. We planted 100 trees in a completely randomized block of 25 each of red and silver maple, Tree-of-heaven and black walnut. The maples were large enough to use during the 2019 season, while the tree-of-heaven and black walnut will require an additional year of growth to be of usable size. To determine how feeding pressure impacts the health of maple trees, two sets of experiments were conducted, first using 4thinstar nymphs followed by a study using adult SLF at high density. Fourth instar SLF nymphs were collected from tree-of-heaven and transported to the common garden on the day of the experimental set-up. In July, 3 densities of 4thinstar nymphs of spotted lanternfly (control = 0 SLF; light density = 15 SLF nymphs; moderate density = 30 SLF nymphs) were introduced into sleeve cages that were placed over vigorous branches of each tree species. Because the trees are still young, we did not use a high-density treatment this time. Nymphs were left on the branches for 11 days when the experiment was terminated. Treatments were randomly assigned, and six replicates were used per treatment for each tree species. Eleven days of feeding by 4th instar nymphs at 0, low and medium densities did not produce significantly different effects on photosynthesis rate for red maple, but silver maple was marginally affected by nymph feeding. Initial photosynthesis was not different from final photosynthesis of the control, and light nymph density. However, moderate SLF density marginally enhanced photosynthesis on the final day of the experiment for silver maple (P=0.06). Stomatal conductance was not different between treatments for either maple species but was instead reduced by the sleeve cage. This is something we will have to take into account next year, so we may try a different material or size of openings to increase air flow. To address the impact of adult SLF pressure on red and silver maple, in Sept. 2019 adults were collected from tree-of-heaven and placed in pop-up cages with foliage for transport to the common garden on the day of experimental set-up. Two sleeve cages were placed over different healthy branches of each tree species (10 each of red maple and silver maple); 40 adult SLF were added to one of the sleeve cages on each tree and the other was left empty. An additional branch was tagged on each tree but did not receive insects or a sleeve cage to determine if the sleeve cage itself affected tree physiology. Control trees (no SLF) received one sleeve cage with no insects, while a second branch without a sleeve cage was flagged for subsequent measurements. Ten replicates were used per treatment for each tree species. All treatments were randomly assigned. Dead SLF adults in all cages were recorded and replaced daily with freshly collected adults for 11 days. In contrast to nymph feeding, adult feeding suppressed photosynthesis for both red and silver maple. Photosynthesis was suppressed by day 3 and remained low for the duration of the experiment when SLF were present compared to control branches with sleeves (P=0.01). Additional analysis of other physiological measurements and carbohydrate concentrations in response to SLF nymph and adult feeding are ongoing.
Publications
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