3
National Science Foundation
Principal Investigator: B. Beckage
Accomplishments & Outputs:
Publications: 3
Hatch
Principal Investigator: B. Beckage
Accomplishments & Outputs:
Publications: 3
National Institute of Food and Agriculture/Department of Agriculture
Principal Investigator: A. Hazelrigg
Accomplishments & Outputs:
Publications:
Hazelrigg, A. Pesticide Applicator Report. 2013. Applying Pesticides in Hot Weather. http://pss.uvm.edu/pesp/PAR/PAR_Spring2013.pdf
3
Vermont ANR Department of Environment Conservation
Principal Investigator: A. Hazelrigg
Accomplishments & Outputs:
Publications: 3
Hatch
Principal Investigator: J. Molofsky
Accomplishments & Outputs:
Publications:
Kaproth, M.A., Eppinga, M.B. and Molofsky, J.2013. Leaf litter variation influences invasion dynamics in the invasive wetland grass Phalaris arundinacea. Biological Invasions 15:1819-1832.
Eppinga, M.B., Pucko, C.A.,Baudena, M., Beckage, B. and Molofsky, J. 2013 A new method to infer vegetation boundary movement from snapshot data. Ecography, 36: 622-635.
Molofsky, J., Danforth, C.M. and Crone, E.E.2013 Nutrient enrichment alters dynamics in experimental plant populations. Population Ecology 10.1007/s10144-013-0392-3. 3
Hatch/Multistate
Principal Investigator: D. Neher
Accomplishments & Outputs:
Publications:
Zhao, J., and Neher, D.A. 2012. Soil nematode genera that predict specific types of disturbance. Applied Soil Ecology 64: 135-141.
Zhao, J., Neher, D.A., Fu, S., Li, Z., Wang, K. 2013. Non-target effects of herbicides on soil nematode assemblages. Pest Management Science 69: 679-684.
Zhao, J., Shao, Y., Wang, X., Neher, D.A., Xu, G., Li, Z., and Fu, S. 2013. Sentinel soil invertebrate taxa as bioindicators for forest management practices. Ecological Indicators 24: 236-239. 3
National Science Foundation
Principal Investigator: D. Ross
Accomplishments & Outputs:
Publications: 3
Hatch/Multistate
Principal Investigator: D. Ross
Accomplishments & Outputs:
Publications:
Lawrence, G.B, I.J. Fernandez, D. deB. Richter, D.S. Ross, P.W. Hazlett, S.W. Bailey, R. Oiumet, R. Warby, A.E. Johnson, H. Lin, A.G. Lapenis, T. Sullivan, J. Kaste. 2013. Measuring environmental change by repeated soil sampling: a North American perspective. J. Environ. Qual. 2013 42: 3: 623-639. doi:10.2134/jeq2012.0378.
3a
Hatch
Principal Investigator: Y. Chen
Accomplishments & Outputs:
Publications:
Izzo, V., D. J. Hawthorne and Y. H. Chen. Published Online. Time of the Season: Effect of photoperiodism on host-mediated cues for diapause induction in Leptinotarsa decemlineata. Ecological Entomology.
Piiroinen, S., L. Lindstrom, A. Lyytinen, J. Mappes, Y. H. Chen, V. Izzo, A. Grapputo. 2013. Pre-invasion history and demography shape the evolution of the insecticide resistance-related acetylcholinesterase 2 gene in the invasive Colorado potato beetle. BMC Evolutionary Biology 13:13.
Alyokhin, A. A., Y. H. Chen, M. Udalov, G. Benkovskaya, and L. Lindstrom. 2012. Evolutionary considerations in potato pest management. In P. Giordanengo, C. Vincent, and A. A. Alyokhin, Insect pests of potato: biology and management. Academic Press. Waltham, MA, USA. 3a
National Institute of Food and Agriculture/Department of Agriculture
Principal Investigator: A. Hazelrigg
Accomplishments & Outputs:
Publications: 3a
Cornell University
Principal Investigator: A. Hazelrigg
Accomplishments & Outputs:
Publications: 3a
Cornell University
Principal Investigator: A. Hazelrigg
Accomplishments & Outputs:
Publications: 3a
University of Minnesota
Principal Investigator: D. Neher
Accomplishments & Outputs:
Publications:
Kidane, E., Hu, W., Chen, S., and Neher, D.A. 2012. Ecology of soils suppressive to the soybean cyst nematode: I. Effect of tillage and crop-biocide treatments on soil suppressiveness to nematode and soybean yield. Journal of Nematology 44:471.
Kidane, E., Hu, W., Chen, S., and Neher, D.A. 2012. Ecology of soils suppressive to the soybean cyst nematode: II. Effect of tillage and crop-biocide treatments on nematophagous fungi. Journal of Nematology 44:472.
Nishanthan, T., Neher, D.A., and Chen, S., 2012. Ecology of soils suppressive to the soybean cyst nematode: III. Association of nematode and microbial communities with soil suppressiveness. Journal of Nematology 44:482.
3a
Agricultural Research Service/Department of Agriculture
Principal Investigator: B. Parker
Accomplishments & Outputs:
Publications:
Trissi, A.N., M. El Bouhsini, M.N. Alsalti, M. von Korff, A. Hamwieh, M. Skinner, B.L. Parker & M. Baum. 2013. Genetic diversity among summer and winter Beauveria bassiana populations as revealed by AFLP analysis. J. Asia-Pacific Entomology 16: 269-273.
Kim, J.S., H.J. Yeon, M. Skinner & B.L. Parker. 2013. An oil-based formulation of Isaria fumosorosea blastospores for management of greenhouse whitefly, Trialeurodes vaporariorum (Homoptera: Aleyrodidae). Pest Management Science 69: 576-581. DOI 10.1002/ps.3497.
Kim, J.S., H.J. Yeon, B.L. Parker, M. Skinner. 2013. Effect of ethoxylation of isotridecyl alcohol on aphicidal activity of fungal supernatant formulation. J. Pesticide Science. 38:1-3. DOI: 10.1584/jpestics.D12-052.
3a
Forest Service/Department of Agriculture
Principal Investigator: B. Parker
Accomplishments & Outputs:
Publications: 3a
Vermont Agency of Agriculture, Food, and Markets
Principal Investigator: B. Parker
Accomplishments & Outputs:
Publications: 3a
University of New Hampshire
Principal Investigator: M. Skinner
Accomplishments & Outputs:
Publications:
Linking Models to Data to Investigate Patterns and Process in Savannas
.
We are examining the importance of fire-feedbacks on savanna dynamics using models and empirical data. The data are collected from sites that have been intensively studies for 1 to 3 decades in southern Florida, southwestern Georgia, and eastern Louisiana, and that broadly represent pine savannas in the southeastern United States. We have constructed both mathematical and computational models to explore system dynamics and structural determinants.
Beckage, B., S. Kauffman, A. Zia, C. Koliba and L. Gross. 2013. More complex complexity: Exploring the nature of computational irreducibility across physical, biological, and human social systems. in Irreducibility and Computational Equivalence: 10 Years After the Publication of Wolfram's A New Kind of Science. Springer Verlag. Peer reviewed book chapter.
Projecting climate change impacts on Vermont forests using dynamic vegetation models
.
We have used global vegetation models to project the responses of forests across New England to regional climate change. We have parameterized the models for regional forest types, downscaled projections of global climate change to the regional level, and then projected the impact of regional warming on composition and distribution of forests across New England. We have used evolutionary algorithms to inversely estimate parameter values in global vegetation models in order to improve model forecasts. We have disseminated results of our work their publication in scientific journals.
Eppinga, M. B., Pucko, C. A., Baudena, M., Beckage, B., and Molofsky, J. 2013. A new method to infer vegetation boundary movement from snapshot data. Ecography 36: 622-635.
Vermont Pesticide Safety Education Program
.
The VT Pesticide Education and Safety Program provides education and training for both commercial and private certified pesticide applicators. Initial certification education and training is also offered for applicators who want to acquire a pesticide license in Vermont. Continuing education and re-certification credits are offered through a twice-yearly newsletter with the VT Agency of Agriculture.
Hazelrigg, A. Pesticide Applicator Report. 2012. Considerations for Avoiding Off-Target Movement of Pesticides. http://pss.uvm.edu/pesp/PAR/PAR-2012Fall.pdf
Compost Bioassay
.
Persistent pesticides in compost can cause plant problems and losses in Vermont gardens and fields. Testing for these pesticides in compost is very costly and not readily available. Plant bio-assays can offer a quick screening method for composters wanting to check their finished compost for levels of contamination that could cause symptoms in plants. The Plant Diagnostic Clinic will offer compost bio-assay testing using replicated trials with 3 indicator plants in a controlled environment for VT commercial compost companies. Submission forms and protocols have been developed and testing will begin in late Fall 2013.
Eco-Evolutionary Feedbacks and the invasive success of introduced Phalaris arundinacea
.
The purpose of this project is to determine how the introduction and interbreeding of individual genotypes from different parts of their native range create invasive individuals in the introduced range that have higher fitness and are more aggressive than the original introduced individuals. The results of this project will allow us to understand how human aided introduction of populations of different individuals can allow for the evolution of traits in the new range that are more aggressive and cause greater harm to the environment than the original introduced individuals.
Eppinga, M. B. and Molofsky, J. 2013. Eco-evolutionary litter feedback as a driver of exotic plant invasion. Perspectives in Plant Ecology, Evolution and Systematics 15:20-31.
Plant-Parasitic Nematode Management as a Component of Sustainable Soil Health Programs in Horticultural and Field Crop Production Systems
.
Three projects contributed to the multistate objective to evaluate cultural management procedures to their impacts on the sustainability of soil health: with special research to the utility of nematode community structure as an indicator of overall soil quality and their roles in plant nutrient cycling. In Project 1, we used high-throughput sequencing approaches to assess the diversity and composition of both bacterial and fungal communities in compost produced at a commercial-scale. Bacterial and fungal communities responded to both compost recipe and composting method. This is the first report of a) hardwood compost containing relatively abundant Acidobacteria, Verrucomicrobia, b) hay being a favorable habitat for Actinobacteria and Gemmatimonadetes, c) Chloroflexi abundant in compost, and d) microbial succession of aerated static pile and vermicompost. The objective of Project 2 was to quantify effects of roads by traffic road type (highway, two-lane paved, and gravel) and distance from the road, on soil forest soil nematode communities, in conjunction with chemical and physical measures of soil quality. Salt concentrations were greatest by two-lane paved roads, while heavy metal concentrations were greatest near highway roads. Nematode community index values reflect increased disturbance closer to the road particularly at the shoulder, with later ecological succession and a shift in the decomposer foodweb with increased distance from the road. The ditch and the forest were areas of increased trophic structure, while abundance of plant-parasites was greatest along the roadside. The results suggest that conscious design and management of the forest buffer and intentional inclusion of a ditch as a roadside feature may minimize pollutant movement and protect surrounding landscapes. Project 3 was a meta-analysis of soil energy pathways of agricultural, forest and grassland ecosystems using nematode trophic group analysis. We concluded that energy pathways are bacterial-dominated in all three ecosystems whether expressed as abundance or biomass. Fungal and herbivorous pathways are second in dominance in forest and grassland ecosystems, respectively. The relative size of the fungal-based energy pathway suggests a gradient of resource quality among ecosystems. We suggest that herbivorous-based energy pathways are more important in grassland ecosystems than reported previously.
Neher, D.A., Weicht, T.R., Bates, S.T., Leff, J.W., and Fierer, N. 2013. Changes in bacterial and fungal communities across compost recipes, preparation methods, and composting times. PLoS ONE 10.1371/journal.pone.0079512.
Neher, D.A., Asmussen, D., and Lovell, S.T. 2013. Roads in northern hardwood forests affect adjacent plant communities and soil chemistry in proportion to maintained roadside area. Science of the Total Environment. 449: 320-327.
Collaborative Research: Landform Controls on Hydrologic Flowpaths and Pedogenesis Explain Solute Retention and Export from Pedon to Catchment Scales
.
Headwater catchments (small watersheds) are inherently complex. The soils, subsoils, and geologic properties exhibit heterogeneity at different scales and stream chemistry draining these areas typically varies from one catchment to another in space and time. Yet these headwater catchments comprise the majority of the landscape and are responsible for setting the quality of water at a regional scale. This project was aimed at explaining the spatial and temporal variation in stream water chemistry at the headwater catchment scale using a hydropedological framework. This framework examined both soil development and stream chemistry from a new perspective. The way in which water chemically evolves along flowpaths in the landscape as it travels to the stream is strongly influenced by the soils through which it passes. In turn, soil development is strongly affected by water flowpaths. The research took place in a small headwater catchment at the Hubbard Brook Experimental Forest. A team of scientists examined how distinct patterns of soil development can be used to interpret sources of solutes in stream water. The overall goal of the project was to develop a predictive model of landform control on hydrologic flowpaths and soil development that explains solute retention and export from an individual soil profile to an entire hillslope to watershed scales. During the final year of the project, we showed that there is much spatial variability in soil composition, but that variability can be quantified and predicted based on topographic characteristics, such as distance to stream or bedrock outcrops. In the past, soil scientists have not often considered lateral soil formation. However, we found that soil materials and specific elements, such as organic carbon, manganese and cerium, were very mobile in the watershed and transported laterally with groundwater, where they accumulate downslope. Soils with laterally deposited materials in the subsurface, such as soils in near-stream zones, were particularly enriched in subsoil carbon. Determining whether specific soils across a watershed would be a source or sink of carbon in a changing climate could benefit from integration of hydropedologic information such as ours. In addition, the soil composition seemed to be a good indicator of vertical vs. lateral groundwater flow because of the mobility of soil materials and specific elements. Soil chemistry could therefore be used in lieu of intensive groundwater monitoring to predict flow directions. Cerium was especially useful as a natural groundwater tracer, because this element was not taken up by plants and tended to accumulate downslope with lateral groundwater flow. Both undergraduate and graduate students were trained and results were reported at national and international scientific conferences. A Ph.D. dissertation is near completion and at least three articles will be submitted to peer-reviewed journals. The major impacts of this project will be a redefinition of how soil development is viewed in these upland catchments, along with a better understanding of how stream chemistry is determined by soils across the landscape.
Bourgault, R., D. Ross, S. Bailey, P. Brousseau, J. Gannon , K. McGuire, and T. Bullen. 2012. Landscape-Scale Pedogenic Relationships between Soil Carbon and Secondary Metal Oxides in Hubbard Brook Podzols, Northeastern US Mineralogical Magazine, 76(6): 1501.
Northeast Coordinating Committee on Soil Testing
.
It is essential that we understand the effects of land management on both carbon sequestration and soil nutrient supply. This project has a number of objectives and over the past year we focused on determining the spatial distribution of nutrients in riparian soils of both the Winooski and Missisquoi Watersheds. In the Missisquoi and two of its tributaries, Black Creek and Hungerford Brook, we worked with cooperating dairy farms and sampled the transition from agricultural field through the riparian buffer to stream bank edge. Samples were taken at four depths: 0-15 cm, 15-30 cm, 30-60 cm and 60-90 cm. Where possible, streambank samples were also obtained. Similar work was performed in the Mad River watershed on a variety of land uses. We determined concentrations of inorganic nitrogen (nitrate and ammonium), total phosphorus, soil test available phosphorus (extracted in pH 4.8 ammonium acetate) and the degree of phosphorus saturation (acid ammonium oxalate method) . To date, about 30 transects have been completed, resulting in over 500 samples. There was a clear decline in nitrate and soil test phosphorus both with depth and along the transect toward the stream. Stream bank samples had unusually low nitrate concentrations that, coupled with high ammonium concentrations, suggested a different oxygen environment. Total soil phosphorus did not vary significantly along the transects. The degree of phosphorus saturation was relatively low in all samples, although higher in the surface samples of tilled agricultural fields and decreasing towards the streams. These results suggest that the riparian buffers are effective in lowering the nutrient content of streambank soils. Streambank erosion would transfer greater quantities of nutrients to surface waters if these buffers were not present. Results are being shared with cooperating farmers, Extension specialists and other researchers. A website detailing our findings is under construction. This work will be extended in the final year of the project with more focus on different land uses and buffer widths.
Young, E.O., D.S. Ross, B.J. Cade-Menun and C.W. Liu. 2013. Phosphorus speciation in riparian soils: a phosphorus-31 nuclear magnetic resonance spectroscopy and enzyme hydrolysis study. Soil Sci. Soc. Am. J. 77(5): 1636-1647. doi:10.2136/sssaj2012.0313.
8 projects
Entomology and IPM
2013 Annual Report Project Narratives
Entomology and Integrated Pest Management
Climate range expansion during colonization of a major crop pest, Colorado Potato Beetle
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The overall goal of this proposal is to examine how climatic and biotic factors have influenced the geographic range expansion of Colorado potato beetle (CPB), and to forecast how climate change may influence the abundance and distribution of beetle populations in the future.
Objectives
1. Characterize how geographic populations (ancestral Mexican and derived US) vary in their ability to tolerate cold climates.
Ancestral and derived populations did not express different physiological responses (i.e. SCPs) to freezing temperatures. However, ancestral and derived populations responded differently to the onset of winter conditions and displayed dissimilar overwintering behaviors. The majority of ancestral beetles failed to initiate diapause and dug upward within experimental mesocosms. Differences in overwintering behavior also resulted in significant variation in overwintering success as derived populations displayed higher overwintering survivorship when compared with ancestral populations.
2. Characterize how geographic populations vary in their ability to feed on their natal plant, Solanum rostratum and potato, Solanum tuberosum
Vermont pest populations displayed a distinctly expanded diet breadth when compared with non-pest derived (Kansas) and ancestral (Texcoco, Morelos and Oaxaca) populations. They also failed to distinguish between cultivated and wild host plants during the feeding choice experiment. Vermont beetles accepted and grew at an equal or higher rate when compared with all other beetles on all host species. Finally, Vermont beetles exhibited a higher growth rate on leaf samples, as opposed to flowers, when compared with all other populations. The greater preference, acceptance, and performance of Vermont beetles on all host species and plant structures underscores the virulence of the pest form of the beetle
3. Population genetic structure and phylogeographic structure of beetle populations.
We have mtDNA and microsatellite (6 loci) data for US and Mexican populations. US pest populations appear to be highly admixed, but do not appear directly descended from Mexican populations. Among the Mexican populations, a phylogeographic analysis using Nei neighboring-joining (FST) found that beetles from Texcoco, Mexico are the most highly related to US beetle populations.
4. Determine if potato plants may induce the likelihood of beetle diapause.
Potato plants grown under short day conditions displayed significantly higher levels of leaf nitrogen compared with long day treated plants. Over 65% of beetles feeding upon short-day treated plants initiated diapause compared with < 20% of beetles placed upon long-day treated plants.
Izzo, V., D. J. Hawthorne, and Y. H. Chen. In review. Geographic variation in winter hardiness of a common agricultural pest, Leptinotarsa decemlineata, The Colorado potato beetle. Evolutionary Ecology
A Comprehensive, Interdisciplinary Vermont Extension IPM Program Addressing Stakeholder Priorities and Needs
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This multidisciplinary project reflects the diversity of Vermont agriculture and addresses the stakeholder needs for current integrated pest management information (IPM). The crops included in this project are agronomic crops, apples and grapes, vegetables and small fruit, greenhouse ornamentals, and home gardens/landscape plants. The faculty involved in each of the 6 subject matter areas assess stakeholder's priorities and educational needs for recurring and new or emerging insects, weeds and diseases. The specific IPM information for these crops is delivered using a wide variety of educational tools including newsletters, websites, annual meetings, workshops, factsheets and through one-on-one contact with phone, email and site visits. Since insect, disease and weed issues continue to change due to pressures of climate change and invasive species, we will continue to assess and address IPM needs for a diverse audience of Vermont stakeholders using a wide variety of educational delivery methods.
none
NE IPM Small Fruit Working Group
.
Small fruit researchers, extension faculty, and representatives from state organic grower associations attended a 3 day workshop in Vermont addressing small fruit integrated pest management. The first day is spent sharing pest and disease problems we have encountered in small fruit crops (strawberry, blueberry, raspberry and grape) in our states over the past year. We also share information on our programs, new publications, newsletters and websites. The second day was spent in the field visiting 4 small fruit farms in VT and NH talking with growers and addressing pest, weed and disease concerns. The third day was spent establishing priorities in research, extension and regulatory issues for small fruit crops in the Northeast. Spotted wing drosophila infestations and root rot issues in strawberries were main discussion items. Information learned will be shared in our respective state's small fruit newsletters, meetings, workshops and field days over the course of the year.
none
National Plant Diagnostic Network for the Food and Agriculture Defense Initiative
.
The purpose of the Northeast Plant Diagnostic Network is to provide a network of Plant Pathologists throughout New England and the US who can respond to new or introduced pathogens or pests with rapid diagnosis. Accomplishments this past year have included training over 200 "First Detectors" to understand how to react and respond when a new pest or pathogen is detected in Vermont. New Forest First Detectors have also been trained for identifying 3 important pests that could affect VT forests and landscapes. All the First Detectors now receive a newsletter just for First Detectors across the NE alerting them of new developments in pest identification and new pest and pathogen introductions. First Detector Training will continue with pests and pathogens of significance.
Managing new and introduced pests, pathogens and invasives costs millions of dollars in the US each year. Training of "First Detectors" helps offer a volunteer network of eyes in communities, farms and landscapes to help detect new pest and disease problems. The benefit of this First Detector Network extends what the Universities and Plant Diagnostic Clinics are able to detect in the field. This network extends across the US and may be the first to detect a new problem pest or disease. The stakeholders need training updating their knowledge of new and invasive pests and pathogens and how to identify new problems.
none
Ecology of Nematode-Suppressive Soils in Midwest Soybean-Cropping Systems
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The soybean cyst nematode (SCN), Heterodera glycines, is a major pest problem in the corn-soybean production in the Midwest. In this project, we used SCN as a model pathosystem to study the ecology of nematode-suppressive soil. A 4-year field experiment was conducted at two locations in southern Minnesota and samples were collected annually at planting, mid-season and harvest. The experiment was a split-plot design with no-till (NT) and conventional tillage (CT) as main plots, and five crop sequence-biocide treatments as subplots with four replicates. Measurements included soybean yield, SCN egg counts, species and abundance of endoparasitic fungi on SCN second-stage juveniles (J2), nematode-trapping fungi, fungal parasites of eggs in cysts, extracellular enzyme activity profiles in soil, and indices of nematode community structure and composition that relate to nematode suppression in the field soil. The treatment effect on SCN population density increased progressively through the 4 year experiment. Tillage generally did not affect SCN population density, but CT increased SCN J2 abundance. The crop-biocide treatment affected SCN population. The smallest egg and J2 counts were observed in the treatment of corn-soybean-corn rotation without biocide treatment before 2012. Application of the fungicide captan resulted in greater SCN numbers at harvest in 2011. No effect of the bactericide treatment was observed on SCN population density at any sampling time. Interestingly, SCN population density in the soybean following rotation with corn rebounded in 2012 to exceed that in soybean monoculture, probably due to interrupted biocontrol. Neither tillage nor biocides affected yield. Conventional tillage or an annual rotation of corn-soybean reduced percentage of J2 parasitized by fungi, e.g., Hirsutella spp. Cultivation decreased abundance of plant-parasitic and fungivorous nematodes and increased abundance of bacterivorous nematodes. The relative abundance of fungivorous nematodes increased when corn was rotated with soybean. Values of total maturity, trophic, and genera diversity indices correlated positively with suppression of SCN suggesting that complex soil communities with later stages of ecological succession foster natural disease suppression. The naturally suppressive soils contained greater activity of chitinase and aminopeptidase than conducive soils. This study suggests that SCN suppression in the fields is aligned more closely with fungi than bacteria, and parasitism of J2 by Hirsutella was the most important component. Natural suppression of SCN appears to be associated with the microbial community fostered by a combination of no-till and soybean monoculture. Agronomic practices for SCN management such as crop rotation have detrimental non-target effects on free-living nematodes and the functional composition of decomposer microbial communities.
Nishanthan,T. 2012. Role of microbial extracellular enzymes and beneficial nematodes on suppression of soybean cyst nematode. Dissertation. University of Vermont, Burlington.
Entomopathogenic Fungi for Management of Pear Thrips, Western Flower Thrips and Other Related Insect Pests with Soil - Inhabiting Stages in Greenhouses and Forests
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A total of 73 fungal isolates were sent to the USDA ARS National Collection of Entomopathogenic Fungi for permanent storage. The fungi were isolated from European fruit lecanium, Parthenolecanium corni; hemlock woolly adelgid, Adelges tsugae ; and ants from Vermont, Rhode Island, New Mexico, Arizona, and Texas. This adds to the existing collection of potentially potent insect-killing fungi ready for further assessment and development into biopesticides. The following species, all of which appeared to have insecticidal capabilities were transferred into the national collection (numbers in parentheses indicate number of different isolates transferred): Beauveria sp.; Lecanicillium sp.; Aspergillus sp.; Penicillium sp.; Fusarium sp.; Alternaria sp.; Cladosporium sp.; Colletotrichum sp.; Rhinocladiella sp.; Epicoccum sp.; Yeast cells; Not identified, but appears to be entomopathogenic.
Two strains of Beauveria bassiana from the UVM Worldwide Collection of Entomopathogenic Fungi were selected for combination to create isolates with superior mycoinsecticidal qualities through nuclear hybridization. One strain (ERL1744) was isolated from western flower thrips (Frankliniella occidentalis , WFT) and demonstrates a high level of virulence and the capacity to grow rapidly. The second strain was isolated from western corn rootworm, Diabrotica virgifera, and has good thermoresistance but comparatively low insecticidal activity against thrips. Wall lysis of blastospores to isolate the protoplasts was carried out using a complex of commercially available enzymes from Trichoderma harzianum at two concentrations, 0.5 and 1 percent with 1M of sucrose. Conjugation, i.e., transfer of genetic material between cells of the two selected isolates, was achieved by mixing blastospores of both isolates in polyethylene glycol (PEG) and centrifuging at 3000 rev per min for 15 min at 15 deg C. The solution was plated from which 20 new isolates were created, 10 per enzyme concentration. Replicated tests of these new isolates and the original two strains were conducted to compare conidial productivity, insecticidal activity to WFT and thermoresistance. All of these are critical characteristics for a mycopesticide. Four of the 20 new strains produced significantly more conidia than the original isolates when grown on millet. Insecticidal activity of the 20 strains was tested against second instar WFT. It was determined that WFT mortality 6 d after treatment was around 50% or more for six of the new isolates, which was as good or better than ERL1744. The faster a fungus kills its host, the less plant damage occurs. After 9 d, mortality rates of 80-90 percent were observed for these six isolates, which was comparable to ERL1744. Three of the new isolates exhibited greater thermoresistance to exposure to 45 deg C for 2 hr than either of the original strains. This enhances its tolerance to adverse storage conditions and improves its efficacy in field or greenhouse crops under a range of environmental conditions.
Skinner, M., B.L.Parker & J.S. Kim. 2013. Role of Entomopathogenic Fungi in Integrated Pest Management, pp: 207-229. In: (D.P. Abrol, ed.). Chapter 11. Integrated Pest Management: Current Concepts and Ecological Perspective Elsevier Publishing.
Hemlock Resource Protection in Northern New England: Assessing the Potential of Myriangium sp., an Insect-Killing Fungus, in Hemlock Woolly Adelgid
.
The hemlock woolly adelgid (HWA)is a major insect pest of eastern and Carolina hemlock throughout the Eastern Seaboard. With assistance from cooperating foresters from New Hampshire, Maine and Vermont, samples from HWA-infested sites were collected and sent to the UVM Entomology Research Lab scientists to inspect them for evidence of an epizootic initiated by an entomopathogenic fungus (Site locations: 4 in VT, 11 in NH and 4 in ME). A variety of sites were sampled, including those showing signs of an epizootic in the past. In general, HWA mortality in these sites averaged between 10-30 percent. Several of the cadavers showed evidence of fungal mycosis, which was associated with a new fungus that is yet to be identified. It is thought it might be a Phoma sp. with entomopathogenic capabilities. While this fungus could have potential for managing HWA, because it is also a known plant pathogen, it is not considered a suitable candidate for further study at this time. Myriangium sp. was isolated at one site which was in southern Vermont. No indication of a fungal epizootic from Myriangium sp. was detected from this sampling effort. State foresters continue to look for HWA infestations with evidence of epizootics, and samples will be taken again in the future if sites are promising.
A spray trial was conducted on hemlock trees infested with hemlock woolly adelgid (HWA) in Vernon, VT. Two isolates of Myriangium sp., one isolated from HWA and one from EHS, were tested in addition to an untreated control and a water blank. Twig samples were inspected 5 weeks after treatment, and after hurricane force precipitation. Mortality among the untreated and water controls was generally less than 5 percent. In contrast mortality among settles in the two Myriangium treatments was between 72 to 85 percent. This represents an increase in mortality of between 60 to 65 percent following treatment. Myriangium was reisolated from HWA cadavers collected from the treated twig samples, but not from the control samples. Twig samples were taken in April 2012, and significantly more live adults and eggs were found on controls than the fungal treated twig samples (around 200-300 eggs on the treated twigs, 25 to 50 on treated twigs). Significant differences in the treatment effects between the two Myriangium isolates were not detected. This suggests a carry-over effect to the next generation though it could be simply a result of the lower base population of HWA following mortality of the settleds. One year after application (Sept 2012), the pattern of treatment effects was similar to that of earlier sampling. Though mortality in the controls was higher than in the previous year, it was still significantly less than that for the two fungal treatments. The fact that significantly higher mortality was observed among the HWA settleds one year after treatment strongly suggests that the fungi are continuing to impact HWA. These results further support the hypothesis that Myriangium has potential to reduce HWA populations, and potentially be sustained within the ecosystem to provide long term management.
Skinner, M., S. Gouli, V. Gouli & B.L. Parker. 2013. Harnessing the Potential of Fungi Associated with Epizootics in Hemlock Woolly Adelgid Populations in Maine, New Hampshire and Vermont. 24th USDA Interagency Research Forum on Invasive Species, Jan. 8-11, 2013, Annapolis, MD. Poster presentation.
An Emerging Problem for Vermont Christmas Tree Growers: Root Aphids
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Root aphids have become a problem in Christmas tree production. Infested seedlings are stunted, chlorotic and susceptible to root rot. They slow tree growth, delay maturity and impact revenues. In the past growers have relied on imidocloprid insecticides for management. The goal of this project is to determine the species of aphids infesting Christmas trees and evaluate the efficacy of releasing the commercially available soil dwelling predatory mite Hypoaspis miles. Aphid specimens were sent to the USDA for identification, but to date a definitive species id has not been provided. Little is known about this group of aphids, including its life cycle or alternate hosts. This information is needed to substantiate the species. The original plan was to release H. miles around infested trees in the spring. However, because the site where the research was to take place was badly flooded, no releases could be made. In addition, the flooding resulted in mortality of many of the trees, preventing us from using the site. The summer was spent locating suitable alternate sites for making a treatment. In the fall a site in northern Vermont was found, where heavy root aphid populations occurred. A mite treatment was made in mid-October, and an evaluation of the trial is currently underway. It is possible that this is not an ideal time to make a treatment, but this will allow us to develop suitable sampling methods for use in subsequent trials. Though it is premature at this time, when available, results will be disseminated to New England growers and could make available, for the first time, a viable biological control option for root aphids.
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Dynamics of Naturally Occurring Fungal-Induced Epizootics of Hemlock Wooly Adelgid
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This project assesses the efficacy and persistence of the entomopathogenic fungus, Myriangium sp. During the 2013 field season, two field trials were conducted on hemlocks infested by hemlock woolly adelgid (HWA). One spray trial was done on a hedgerow that was heavily infested at one end, and mostly free of HWA at the other. The infested section of the hedge was sprayed with the fungus on 16 May and again on 21 August 2013. HWA abundance and mortality was evaluated over the entire hedgerow before and after application. Pre-treatment samples indicated there were 7-12 HWA and 134 - 240 eggs per 5 cm of hemlock twigs on the heavily infested end and 0.3-5 HWA and 6 - 100 eggs on the less infested section. Mortality of crawlers 2 wk after treatment was 92 percent in the sprayed area and 82 percent in the unsprayed area. Mortality of settlers was 81 percent in the sprayed area and 61.7 percent in the unsprayed area. After 4 wk mortality of settlers on the new growth in the sprayed area was 35.8 percent compared with 6.7 percent in the unsprayed area. After 14 wk most hemlock twigs had new growth and mortality of settlers on this growth was 42.8 percent on the sprayed area and 11.1 percent on the unsprayed area. After the August treatment, HWA mortality on treated twigs was 80.3-100 percent. The untreated area had very few settlers, and over 50 percent were dead. A second field experiment was conducted at a different site in which fungal treatments were made twice, on individual HWA infested branches (16 May, and 21 August 2013). Twig samples were taken on sprayed and unsprayed branches on treated and control trees. Control trees were sprayed with water only. Pretreatment sampling indicated evidence of the presence of the fungus Phoma sp. in the natural population. This is a known phytopathogen with entomopathogenic properties. Twig samples were collected before spray, 2 hr after spray, and after 2 and 7 wk. Before treatment mortality of settlers on old growth was 3.9-17.1 percent and 0-22.5 percent on the control twigs. After 7 wk, mortality of settlers on old growth was 76.8-93.1 percent on sprayed twigs; 55.3-91.7 percent on sprayed twigs and 12-50 percent on control trees. The insects from each samples were used for identify the cause of mortality and to isolate fungal pathogens. Results from both field experiments demonstrated the pathogenic activity of Myriangium sp. to HWA and its ability to circulate within HWA populations. The mechanism of dispersal of the fungus is unknown.
Work continued to determine if Myriangium sp. exists endophytically in hemlock tissues. Several cultures of fungi from genus Phoma (=Diaporthe) and some others forming black pigments were isolated from hemlock tree tissues which were treated with conidial suspension of Myriangium sp. Myriangium sp. was not isolated, suggesting it does not grow within plant tissue.
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