Progress 05/01/19 to 04/30/25
Outputs
Target Audience:The primary audience is the cranberry industry (growers, packers, processors) and associated stakeholders (consultants, chemical companies, commodity groups). An additional audience is fellow entomologists and plant scientists interested in plant defenses and priming by environmental cues and applied research results. Changes/Problems:From 2020-2022, we struggled to make research progress because of COVID restrications at Penn State and USDA facilities. In 2023-2024, at Penn State, we made little progress because we had used our allocated funding in previous years. Nevertheless, we receive cranberry plants from an unfunded collaborator and co-PI Steffan was able to send some caterpillars for the experiment we describe above. At USDA-ARS in Wisconsin in 2023-2024, we had no success hiring a suitable postdoctoral candidate. For 2024-2025, the team at Penn State rebudgeted the funds from Wisconsin and Yip and Tooker used them to conduct the experiment described above to further explore the capacity of cranberries to perceive and respond to pheromones of Sparganothis sulfureana, a key lepidopteran pest of cranberries. What opportunities for training and professional development has the project provided?At Penn State, this project was primarily pursued by Eric Yip, Assistant Research Professor. Dr. Yip was assisted each year by two to three undergraduate research assistants. Through this project, Dr. Yip gained experience mentoring and directing undergraduate students. The undergraduate students were exposed to the details and logistics of conducting greenhouse experiments, imposing treatments on plants, the logic of choosing proper controls, assessing plants for damage, and processing plants for their phytohormone content. How have the results been disseminated to communities of interest?Due to prolonged effects of COVID restrictions at USDA-ARS, our target audience has not learned much about our project. Co-PI Steffan continues to interact with cranberry growers in Wisconsin and seeks opportunities to promote the potential benefits of our research project to cranberry growers, and these stakeholders are enthusiastic about the potential of pheromone-mediated defenses. As we finish analyzing our remaining samples and analyze all our data, we will prepare manuscript(s) for peer-review. Upon acceptance of our manuscript, co-PI Steffan will promote our research results and share a message that this alternative form of insect control adds to efficacy of the mating disruption system that he is developing and has potential to reduce reliance on insecticides and help improve environmental and human health in and around cranberry production areas. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
From 2020-2022, our progress on our project was severely limited by institutional COVID restrictions that made research challenging. In particular, we struggled to establish and maintain a robust colony of Sparganothis fruitworm (Sparganothis sulfureana), the main pest species that we have been studying. Due to a lack of access to field sites in WI, we were unable to establish colonies of cranberry fruitworm (Acrobasis vaccinii) and blackheaded fireworm (Rhopobota neavana). When we could get caterpillars, our research focused on S. sulfureana; otherwise, we studied spongy moth caterpillars (Lymantria dispar), a generalist caterpillar species that is an occasional pest of cranberry that we were able to obtain from a USDA lab. No-cost extensions were vital in providing additional time to make progress on some portions of the objectives of our project. We discovered that spongy moth caterpillars feeding on cranberry plants exposed to pheromones of Sparganothis fruitworm did not grow well and lost weight compared to caterpillars that fed upon plants that were not exposed to pheromone. Moreover, cranberry plants exposed to pheromones and feed upon by caterpillars showed a trend for having altered phytohormone profiles, which are key for better resisting caterpillar feeding. Our work in the 2023 and 2024, highlighted below, clarified and expand on these results. Objective 1: At Penn State in 2023, with limited funds we continued to test whether exposure to mating disruption levels of moth sex pheromones can prime cranberry defenses and offer a possible avenue of pest control. We exposed plants to either fertilizer pellets imbued with a blend of moth sex pheromones, or controls without the pellets. We then caged Sparganothis sulereana caterpillars to stolons to record damage and collect damaged leaves for additional analyses on phytohormones. However, we had difficulty procuring S. sulfereana, and did not have suitable herbivores until late in the year. We tested 12 caterpillars on eight plants, but with this limited sample size, we found no effect of pheromone exposure on either caterpillar weight gain (Linear mixed model with plant ID as a random effect: Χ2 = 0.74, P = 0.39) or number of damaged leaves (Linear mixed model with plant ID as a random effect: Χ2 = 0.33, P = 0.57). When these data are added to data from previous years using S. sulfereana, there was no effect of exposure on caterpillar weight gain (Linear mixed model with plant ID as random effect: Χ2 = 0.30, P = 0.58) or number of damaged leaves (Linear mixed model with plant ID as random effect: Χ2 = 0.05, P = 0.83). Objective 2: Because methyl jasmonate (MeJA) is one of the most important phytohormone-mediated signaling pathways for plants, we expected that cranberries would respond to direct applications of MeJA. With this hypothesis in mind, we tested how caterpillars (larval Sparganothis sulfureana, a major pest of cranberries) responded to cranberry plants that had been exposed to foliar applications of MeJA. In Wisconson during the summer of 2023, we applied MeJA directly to three varieties of cranberries ('Pilgrim,' 'Ben Lear,' and 'Stevens'). Untreated control plants received no MeJA treatment. All plants were maintained within an incubator (photoperiod set at 12:12). After exposure to MeJa, we placed second-instar S. sulfureana larvae (N = 6) on each plant. After 10 days, we measured larval size and survivorship. The number of S. sulfureana larvae that survived on MeJA- plants was marginally lower on Pilgrim cranberries (P = 0.086). In contrast, survivorship was similar between MeJA-primed and unprimed plants for 'Ben Lear' and 'Stevens' cranberries, although it is worth noting that the untreated controls experienced surprisingly high larval mortality. Across the three cranberry varieties, there was no significant evidence of a cultivar effect (F2,9 = 1.453, P = 0.284), MeJA treatment effect (F1,9 = 0.258, P = 0.623), or interaction between cultivar and MeJA (F2,9 = 2.449, P = 0.141) We also measured the total biomass of S. sulfureana larvae surviving on MeJA+ or MeJA- plants. We collected this information caterpillar mass can account for sub-lethal effects (e.g., larvae performing poorly on plants with stronger host-plant defenses). We found significant evidence that total larval biomass was lower on 'Pilgrim' cranberry plants treated with MeJA than untreated plants (P = 0.0151). As with mean larval survivorship, there was no evidence that total larval biomass was affected by MeJA on Ben Lear and Stevens plants. Again, total biomass was surprisingly low on the untreated Ben Lear and Stevens cultivars. With more typical larval survivorship on untreated controls, the results would allow for more confident conclusions. Altogether, the significantly reduced larval biomass on Pilgrim cranberries, as well as the declining trend in larval numbers on MeJA-primed plants, suggests this experiment would benefit from repeated trials. In 2024, with a rebudgeting of funds originally allocated to co-PI Steffan, Yip and Tooker were able to conduct an important greenhouse experiment to solidify whether cranberry plants can detect and respond to mating disruption-levels of the pheromone of S. sulfureana. We tested 143 cranberry plants in late summer 2024. We exposed one third of plants to the full mating-disruption blend of S. sulfureana sex pheromones at levels similar to those used for mating disruption in the field (termed the "pheromone" treatment). We had two control groups: one third of plants were exposed to only the solvent used to deliver the pheromone blend ("control" treatment), and the final third of plants were exposed to the pheromone of sunflower head moth ("SHM" treatment). This latter treatment presented a mating-disruption dose of a pheromone from a pest species that does not attack cranberries and therefore controls for presence of a high dose of a general pheromone. If cranberry plants have evolved an ability to perceive and respond to high doses of pheromone, we expect that trait is specific to a co-evolved pest like Sparganothis sulfureana, not a non-coevolved pest like Homoeosoma electellum. We removed these treatment cues after 3 days and placed 1 mid- to late-instar S. sulfureana caterpillar inside a clip cage sealed along a cranberry branch. We allowed caterpillars to feed for 48 h before assessing damage and collecting leaves for phytohormone analysis. Plants exposed to the S. sulfureana pheromone had lower levels of leaf damage (F2,101 = 6.1, P = 0.003); however, caterpillars on these plants had similar growth to control plants (F2,72 = 2.4, P = 0.096). Caterpillars feeding on SHM plants tended to gain more weight (pairwise comparison between SHM and control caterpillars: t = 2.01, P = 0.048). Phytohormones quantified by HPLC analysis found that cranberry exposed to the moth pheromone blend had lower levels of ABA than both control and SHM pheromone exposed plants (F2,82 = 17.0, P < 0.0001). There was a non-significant trend for pheromone-exposed plants to have lower JA than the other two treatments (F2,82 = 1.7, P = 0.19; if SHM and controls are pooled F1,83 = 3.4, P =0.069). JA here is the combined trans and cis isomers. There was no difference in levels of SA (F2,81 = 1.6, P = 0.20), and IAA was largely not detectable in our samples. This is a preliminary analysis, as we have additional replicates that will with process using GC-MS. These results are notable because ABA levels can modulate plant defense responses by some anti-herbivores genes. We do not know which genes might be involved in this defensive response of cranberries. These results suggest that cranberry plants can perceive and respond to mating-disruption levels of pheromones from S. sulfureana and not pheromones generally, indicating that their response may be tuned by co-evolution and could be harnessed for pest control.
Publications
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Progress 05/01/23 to 04/30/24
Outputs
Target Audience:The primary audience is the cranberry industry (growers, packers, processors) and associated stakeholders (consultants, chemical companies, commodity groups). Changes/Problems:At Penn State, we made little progress in 2023-2024 because we used our allocated funding in previous years. Nevertheless, we receive cranberry plants from an unfunded collaborator and co-PI Steffan was able to send some caterpillars for the experiment we describe above. At USDA-ARS in Wisconsin in 2023-2024, we had no success hiring a suitable postdoctoral candidate. For 2024-2025, the team at Penn State rebudgeted the funds from Wisconsin and will use them to conduct the detailed experiment mentioned above. What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest?Due to linger effects of COVID restrictions at USDA-ARS, our target audience has not learned much about our project. Co-PI Steffan continues to interact with cranberry growers in Wisconsin. Nevertheless, he continues to promote the potential benefits of our research project to cranberry growers, and these stakeholders are enthusiastic about the potential of pheromone-mediated defenses. What do you plan to do during the next reporting period to accomplish the goals?At Penn State, we planning in detailed greenhouse experiment to further explore whether cranberries can be primed by exposure to pheromones of lepidopteran pests of cranberries.
Impacts
What was accomplished under these goals?
Objective 1: At Penn State in 2023, with limited funds we continued to test whether exposure to mating disruption levels of moth sex pheromones can prime cranberry defenses and offer a possible avenue of pest control. We exposed plants to either fertilizer pellets imbued with a blend of moth sex pheromones, or controls without the pellets. We then caged Sparganothis sulereana caterpillars to stolons to record damage and collect damaged leaves for additional analyses on phytohormones. However, we had difficulty procuring S. sulfereana, and did not have suitable herbivores until late in the year. We tested 12 caterpillars on eight plants, but with this limited sample size, we found no effect of pheromone exposure on either caterpillar weight gain (Linear mixed model with plant ID as a random effect: Χ2 = 0.74, P = 0.39) or number of damaged leaves (Linear mixed model with plant ID as a random effect: Χ2 = 0.33, P = 0.57). When these data are added to data from previous years using S. sulfereana, there was no effect of exposure on caterpillar weight gain (Linear mixed model with plant ID as random effect: Χ2 = 0.30, P = 0.58) or number of damaged leaves (Linear mixed model with plant ID as random effect: Χ2 = 0.05, P = 0.83). Objective 2: Because methyl jasmonate (MeJA) is one of the most important phytohormone-mediated signaling pathways for plants, we expected that cranberries would respond to direct applications of MeJA. With this hypothesis in mind, we tested how caterpillars (larval Sparganothis sulfureana, a major pest of cranberries) responded to cranberry plants that had been exposed to foliar applications of MeJA. In Wisconson during the summer of 2023, we applied MeJA directly to three varieties of cranberries ('Pilgrim,' 'Ben Lear,' and 'Stevens'). Untreated control plants received no MeJA treatment. All plants were maintained within an incubator (photoperiod set at 12:12). After exposure to MeJa, we placed second-instar S. sulfureana larvae (N = 6) on each plant. After 10 days, we measured larval size and survivorship. The number of S. sulfureana larvae that survived on MeJA- plants was marginally lower on Pilgrim cranberries (P = 0.086). In contrast, survivorship was similar between MeJA-primed and unprimed plants for 'Ben Lear' and 'Stevens' cranberries, although it is worth noting that the untreated controls experienced surprisingly high larval mortality. Across the three cranberry varieties, there was no significant evidence of a cultivar effect (F2,9 = 1.453, P = 0.284), MeJA treatment effect (F1,9 = 0.258, P = 0.623), or interaction between cultivar and MeJA (F2,9 = 2.449, P = 0.141) We also measured the total biomass of S. sulfureana larvae surviving on MeJA+ or MeJA- plants. We collected this information caterpillar mass can account for sub-lethal effects (e.g., larvae performing poorly on plants with stronger host-plant defenses). We found significant evidence that total larval biomass was lower on 'Pilgrim' cranberry plants treated with MeJA than untreated plants (P = 0.0151). As with mean larval survivorship, there was no evidence that total larval biomass was affected by MeJA on Ben Lear and Stevens plants. Again, total biomass was surprisingly low on the untreated Ben Lear and Stevens cultivars. With more typical larval survivorship on untreated controls, the results would allow for more confident conclusions. Altogether, the significantly reduced larval biomass on Pilgrim cranberries, as well as the declining trend in larval numbers on MeJA-primed plants, suggests this experiment would benefit from repeated trials.
Publications
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Progress 05/01/22 to 04/30/23
Outputs
Target Audience: The primary audience is the cranberry industry (growers, packers, processors) and associated stakeholders (consultants, chemical companies, commodity groups). Changes/Problems:Delay on our progress are due to tight restrictions on research during COVID. We are working to compensate for time lost during lock down. What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals?
Impacts
What was accomplished under these goals?
Objective 1: In a greenhouse experiment, we examined the capacity of MeJA to induce defenses responses against a major insect pest species of cranberries. Specifically, we measured the effects of MeJA-induced defenses on growth of larvae of Sparganothis fruitworm (Sparganothis sulfureana). Using 4-L glass vessels, we place three cranberry plants in each of 12 glass vessels. We exposed half (N = 6) to MeJA for 48 h and the other half were left as untreated controls. The experiment included two cranberry cultivars: 'Stevens' and 'Ben Lear.' After MeJA exposure, we allowed plants to off-gas for 24 h, then placed Sparganothis larvae (5 per vessel) on cranberry foliage to establish and feed. For the following two weeks, we counted larvae every 2-3 days. In control vessels, approximately 60% of the larvae survived, while in the treated vessels, no larvae survived. Our results clearly indicate that MeJA-induced defenses of the cranberry plant can be significant. Our next step will be to establish if MeJA-induced defenses are more significant following exposure to moth pheromones.
Publications
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Progress 05/01/21 to 04/30/22
Outputs
Target Audience:The primary audience is the cranberry industry (growers, packers, processors) and associated stakeholders (consultants, chemical companies, commodity groups). Changes/Problems:COVID restrictions have stymied our progress. We hope our one-year extension will allows us to make significant progress. What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest?Due to COVID restrictions, our target audience has not learned much about our project. Co-PI Steffan continues to interact with cranberry growers in Wisconsin, but his meetings were restricted to phone calls and online forums. Nevertheless, he continues to promote the potential benefits of our research project to cranberry growers, and these stakeholders are enthusiastic about the potential of pheromone-mediated defenses. What do you plan to do during the next reporting period to accomplish the goals?In the next year, we hope to be able to promote our research results and share a message that this alternative form of insect control has potential to reduce reliance on insecticides and help improve environmental and human health in and around cranberry production areas.
Impacts
What was accomplished under these goals?
The goal of this project is to explore and understand the capacity of cranberry plants (Vaccinium macrocarpon) to detect the sex pheromones of their native lepidopteran pest species and alter their defensive status to better protect themselves against caterpillar feeding. Our progress in the last year was severely limited by institutional COVID restrictions which made research challenging. In particular, we struggled to establish and maintain a robust colony of Sparganothis fruitworm, the main pest species that we have been studying. Our approved one-year no-cost extension should make up for this limitation and allow us to make important progress on our project. Nevertheless, by using spongy moth caterpillars (Lymantria dispar), a generalist caterpillar species that is an occasional pest of cranberry, we have made some progress. Via experimental work in the lab, we discovered that spongy moth caterpillars feeding on cranberry plants exposed to pheromones of Sparganothis fruitworm did not grow well and lost weight compared to caterpillars that fed upon plants that were not exposed to pheromone. Moreover, cranberry plants exposed to pheromones and fed upon by caterpillars showed a trend for having altered phytohormone profiles, which are key for better resisting caterpillar feeding. In the field, large-scale deployment of pheromones has been shown to reduce the survival of Sparganothis fruitworm larvae feeding within the cranberry canopy. Our work in the next year will seek to clarify and expand on these results.
Publications
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Progress 05/01/20 to 04/30/21
Outputs
Target Audience:The primary audience is the cranberry industry (growers, packers, processors) and associated stakeholders (extension professionals, consultants, chemical companies, commodity groups), as well as scientists that work with pest management in food crops, particularly entomologists and plant scientists. Changes/Problems:COVID restriction greater limited our progress on our project.We were not able to complete field work and only conducted minimal greenhouse-based research. We hope research will be easier in the coming year. What opportunities for training and professional development has the project provided?In Pennsylvania, postdoc Eric Yip encountered significant challenges to our research progress. He showed creativity and flexibility by looking into alternative herbivore species and collaborating with colleagues on campus to secure a steady supply of gypsy moth caterpillars. Eric trained an Penn State undergraduate student (John Sauter, who earned a minor in entomology) to conduct phytohormone analyses and help with behavioral bioassays. In Wisconsin, two undergraduate students (Molly Bidwell, Ellen Koch) were trained on how to sample cranberry insects within pheromone-disrupted blocks at commercial cranberry marshes. This work was part of an ongoing mating disruption project that has been documenting efficacy within large-scale pheromone deployment systems. These students worked part-time, for approximately 6 weeks during May and June, 2020. How have the results been disseminated to communities of interest?Results have been presented at the 2020 Wisconsin State Cranberry Growers Association (WSCGA) winter meeting, the spring mini-clinic, and the fall WSCGA Research Roundtable. What do you plan to do during the next reporting period to accomplish the goals?With COVID restrictions easing at our universities and the USDA, we are optimistic that we can resume our planned investigations. In Pennsylvania, we will re-establish cranberry plants in our greenhouse, and re-start a colony of sparganothis fruitworm. We will begin again plant assays with caterpillars feeding on pheromone-exposed and unexposed plants, which we evaluate for feeding damage and phytohormone production. In Wisconsin, we are planning another year of field evaluation of the influence of mating disruption on caterpillar growth and mortality.
Impacts
What was accomplished under these goals?
Due to COVID-imposed constraints, we struggled to remain productive. We performed limited greenhouse work because we did not have a consistent source of insects to study.Keeping their colonies going was challenging with COVID, and we were not allowed to travel to replenish our colony.No field work involving pheromone-induced plant defenses was attempted during the spring or summer of 2020. These are the items we were able to accomplish despite COVID restrictions: Created new means of loading pheromones into fertilizer granules, then did small-scall tests of pheromone release longevity. Established in Wisconsin new cultures ofSparganothis sulfureana(sparganothis fruitworm) andSystena frontalis(flea beetles) for subsequent screening of plant defense lethality. Because COVID restrictions limited our ability to maintain populations of cranberry pests, we used gypsy moth (Lepidoptera: Erebidae:Lymantria dispar dispar) caterpillars as our focal herbivore species. Previous research has shown that gypsy moth caterpillars can be susceptible to inducible defenses of cranberry plants. With this new focal species, our experiments revealed that cranberry plants exposed to pheromones of sparganothis fruitworm had significantly elevate defenses because gypsy moth caterpillars that feed upon pheromone-exposed plants gained significantly less mass than caterpillars feeding on plants that were only exposed to the solvent control. Our phytohormone analyses have not revealed which compounds may be involved in this response.
Publications
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Progress 05/01/19 to 04/30/20
Outputs
Target Audience:Audiences include scientists, the cranberry industry (growers, packers, processors) and associated stakeholders (consultants, chemical companies, commodity groups). Changes/Problems:We have encountered some difficulties with cranberry culturing in the greenhouse and rearing S. sulfureana in the laboratory, but feel we have developed a system that will be successful in the coming year. More importantly, the COVID-19 outbreak has limited our ability to conduct experiments this spring, but we hope to begin in earnest once restrictions are lifted. What opportunities for training and professional development has the project provided?At USDA/Wisconsin, undergraduate researchers assisted with field experiments gaining valuable research experience. At Penn State, a MS student and postdoc are active on the project and these two individuals have been able to experience some of the challenges of establishing protocols for raising new plants species and rearing new research species. The MS student gave her first talk at a scientific conference and excelled. The postdoc is gaining experience helping to supervise and advise the MS student. How have the results been disseminated to communities of interest?Results have been presented at the North American Cranberry Research and Extension Workers meeting, as well as at three grower meetings hosted by the Wisconsin State Cranberry Growers Association. Further, a new manuscript has been drafted for publication in a peer-reviewed journal. Theoretical justification, experimental plan, and preliminary results were shared with the Annual Meeting of the Entomological Society of America in St. Louis in November 2019. What do you plan to do during the next reporting period to accomplish the goals?We plan to pursue lab and greenhouse experiments to gain insight on the plant defense response, its specificity, and its effectiveness in protecting cranberries against herbivory.
Impacts
What was accomplished under these goals?
1) Documented evidence that a key pest of cranberries (caterpillars of the moth, Sparganothis sulfureana) suffered increased mortality when caged on plants that had been exposed to S. sulfureana sex pheromones. This represented the first evidence that an agricultural crop could eavesdrop on courtship pheromones of its herbivores, then deploy defensive responses that significantly reduced pest survivorship. 2) Field-scale mating disruption system in which lepidopteran larvae (Sparganothis sulfureana) were impacted by the induced defenses of the cranberry plant. The defenses were induced by the broad deployment of insect sex pheromones at commercial cranberry marshes in Wisconsin. Larvae had been caged on cranberry uprights (4 larvae/ cage), and the mean larval density in cages in pheromone-treated beds was 0.85 larvae, compared to 2.3 larvae/cage in the control beds. This finding mirrored prior work, though smaller scale, within a greenhouse setting. In the greenhouse, significant mortality was found in S. sulfureana larvae that had been reared on cranberry plants that had been previously dosed for 48 hrs with insect sex pheromones. 3) Altogether, this represented evidence of increased efficacy of pheromone-based mating disruption. Mating disruption programs interfere with mate finding, but ultimately mating often does occur, even under ideal circumstances. Importantly, the present study has provided evidence that even the "escapees" (the progeny of those moths that did find mates) can be suppressed by induced defensive responses in the plant. 4) In our efforts to understand mechasnisms involved in the plant response, the Tooker lab has been working to understand the logistics of growing cranberries and rearing Sparganothis sulfureana. After some trial and error, we have established effective protocols for raising plants and rearing caterpillars. We have also determined the best length for greenhouse feeding trials (48 h) so that plants experience enough damage and plant defense pathways are triggered. We have also determined an effective way to confine caterpillar to plants and not letting them escape without limiting their access to food.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Golinski, J. E., E. Yip, and J. F. Tooker. Plant defense by eavesdropping on the communication of herbivores: Is it common or rare? Annual Meeting of the Entomological Society of America, St. Louis, MO, November 2019.
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