Abstracts: abstracts from 2009 son/ses meeting
Journal of nematology
A full-day, hands-on workshop was developed to educate and train participants on nematode biology and ecology, diagnosis of symptoms, sampling, on-farm visual assessment using soil bioassays for Meloidogyne hapla and Pratylenchus penetrans and management of plant-parasitic nematodes on vegetables, small fruit and ornamentals. With financial support from the NE-SARE Professional Development program, from 2007 to spring 2009, a total of nine workshops have been held in New York, Connecticut,
... nt, Rhode Island, New Jersey and Maine. The participants were comprised of county extension educators, crop consultants, university personnel, federal and state government employees and interested growers. The workshops were advertised and promoted in state and regional newsletters, email list-serves, grower meetings, webpostings and through direct communication with project leaders, county extension educators and previous workshop participants. Participants received a binder containing hardcopy resources as well as a CD-Rom containing workshop Power-Point presentations, fact sheets and bioassay protocols. In addition, soil sampling and bioassay kits for root-knot and lesion nematodes were also provided. The goal of these workshops is to facilitate the dissemination of knowledge on the diagnosis, assessment and management of plant-parasitic nematodes to enable growers to manage nematode problems on an as needed basis with the ultimate goal of encouraging growers to design a whole-farm nematode management plan (whole-farm nematode management IPM program). Specific examples of workshop activities and feedback from participants will be shared during the workshop session. A follow-up survey will be distributed to all participants in the upcoming year to assess how the skills and knowledge acquired during the workshop were incorporated into their various and/or communications with growers or if the participant was a grower what impact has it had on their production practices and pest management decisions. CHANGES IN PROTEIN CONTENT AND ENZYMATIC ACTIVITY OF TOMATO PLANTS IN RESPONSE TO NEMATODE INFECTION. Abd-Elgawad 1 , Mahfouz M. M., Sanaa The tomato cultivars, Super Marmand and GS-12 were susceptible to the root-knot nematode Meloidogyne incognita while the cultivar Castle Rock was moderately resistant as demonstrated by the common root gall index, nematode-reproduction factor and plant growth parameters. Protein content as well as endo-and exo-glucanase activities in leaf extracts of these cultivars were estimated one week after M. incognita inoculation and/or addition of garlic extract (600 g ground garlic cloves/ l water) as biocontrol agent. Also, catalase, ß-1,3-glucanase and peroxidase activities in plant roots differed among these treatments, two weeks after nematode inoculation. The effects of such treatments on the tested protein and enzymes were presented and discussed. A pressing issue facing ecosystem ecologists today is the ability to predict how biodiversity will respond to global changes (land use, climate change). Additionally, little is known of the roles biotic and abiotic factors play in ecosystem assembly over space and time. We suggest that understanding how biodiversity responded to change in the past offers a logical framework for examining the range of potential changes that can be expected to occur in the future. Research programs in historical ecology, evolutionary biology, and molecular systematics have developed analytical tools that can inform the universe of possible future evolutionary responses. We propose a novel method for investigating soil food webs and distribution ecology that treats the players in soil food webs as co-evolving entities in time and space, with additional consideration for geophysical constraints. We suggest that our approach can reveal patterns of soil community assembly over time and space, and serve as a framework to test hypotheses of biotic and geophysical drivers of trophic relationships. We are developing networks of soil sensors that can be coupled with high-resolution automated minirhizotron (AMR) units to track dynamics of soil organisms and processes. These networks are comprised largely of off-the-shelf components, which can be configured and spatially arranged to best address questions of interest. Included are sensors for CO 2 , temperature, soil moisture, soil water potential, nitrate, and ammonium. In addition, at each location, we have atmospheric sensors for PAR, air temperature, precipitation, and relative humidity. We also utilize sapflow, tower flux estimates, and leaf phenology imagery describing plant activity. From the data output, we can model in situ respiration (CO 2 production) and soil CO 2 flux (soil respiration) using diffusion models modified for soil conditions. We have embedded conventional minirhizotron tubes at all locations for root and rhizomorphs observations. We have designed and are testing an automated minirhizotron built around a USB-port microscope for observing individual hyphal dynamics. By coupling camera, plant, and soil flux activity, we can begin to relate both timing and lags regulating integrated activities of soil organisms and plants. Finally we add direct soil extractions coupled with buried slides extracted and sequenced to characterize the fungal taxa present. The sensors and camera systems are web-based, so we will link into the James Mount San Jacinto NRS to observe streaming datasets and images. We will describe some of the benefits of these integrated systems as well as discuss issues problematic and in need of additional research. Our goal is to provide an overview of the potential for use of this approach, identify potential problems that can be further addressed, and begin to develop a network of soil ecologists interested in collaborations. ECOSYSTEM SERVICES PROVIDED BY TURFGRASS AND LANDSCAPE PLANTINGS. Amador, Jose A. Laboratory of Soil Ecology and Microbiology, 024 Coastal Institute, Univ. of Rhode Island, Kingston, RI 02881. Landscape plantings can provide important -and often ignored -ecosystem services, playing a role in the regulation of carbon, nutrient and hydrologic cycles in urban and suburban ecosystems. We present data from three studies that evaluated different aspects of the ecosystem services provided by landscape plantings, including turf. In the first study, comparisons Abstracts 301 among an established turf plot, a wooded area, and a corn field indicated that turf had values that were intermediate between the wooded area and the corn field for soil bulk density, infiltration rate and soil organic matter content. No differences among land uses were observed for soil C and microbial biomass C. By contrast, the CO 2 flux for the turf plot was similar to the wooded area, and higher than that for the corn field. In the second study, the effects of turf death on nitrate leaching under established turf were examined. Nitrate levels were higher in pore water below the root zone following turf death, a difference that persisted for a year. Carbon mineralization and microbial biomass C were not different between soils from healthy and killed plots. The mass of NO 3 leached from killed plots was three times that from healthy plots. In the third study, NO 3 levels in pore water below the root zone were compared in areas with turf, areas with seven different types of ornamental landscape plantings, and a wooded area. Pore water NO 3 concentrations below the root zone were highest under ground covers, unplanted-mulched areas, turf, deciduous trees, and evergreen trees, with no differences among these vegetation types. Lower values of NO 3 were observed under woodlands, annual and perennial flowers, and evergreen and deciduous shrubs. Mass losses of NO 3 due to leaching were lowest for the woodlands and highest under ground covers. Together, these studies suggest that landscape plantings can carry out some of the same ecosystem services provided by vegetation in unaltered landscapes, although their magnitude may differ. Furthermore, the type of planting is an important factor in determining whether positive or negative effects on ecosystem services are observed, particularly with respect to NO 3 leaching. Two hundred and thirty five isolates of fungi associated with naturally infected eggs and females of root-knot nematodes, Meloidogyne spp., were isolated and screened by the tissue culture plate method. Twenty-seven isolates, including 4 Paecilomyces lilacinus, 10 Pochonia chlamydosporia, 11 Fusarium spp. and 2 Acremonium spp., with high levels of egg parasitism, egg hatch inhibition and juvenile mortality were obtained. The alginate pellet formulations containing P. lilacinus and P. chlamydosporia separately were developed and evaluated against the root-knot nematode Meloidogyne incognita on tomato under greenhouse conditions. In pot experiment, dried pellets of both fungi were applied at ratio of 0.2%, 0.4%, 0.8% and 1.6% (w/w, pellets/soil). The highest root galling reduction by P. lilacinus was 50%, while the highest nematode population decrease by P. chlamydosporia was 91% both at the application rate of 1.6%. In the greenhouse plot experiment, the control effectiveness of alginate pellet formulation of P. lilacinus, the fumigant nematicide (Dazomet) and the nonfumigant nematicide fosthiazate alone or the combinations of the fungus with either chemical nematicide was evaluated. A significant reduction in root galling index was obtained with all the treatments compared with the control. The root galling index was reduced up to 60, 46 and 21% by P. lilacinus pellets, 80, 69 and 86% by Dazomet + P. lilacinus and 70, 69% and 71 by fosthiazate + P. lilacinus 43, 96 and 157 days after of tomato transplantation, respectively. The control efficacy of rootknot nematode was higher by fungal pellets combined with nematicides than nematicides along, suggested that the combined application of the fungal agents with fumigant or fosthiazate could be one of useful strategy for root-knot nematode control. We conducted a controlled outdoor mesocosm experiment over two growing seasons to assess the effects of plant community composition and functional group richness on wetland function, with a focus on methane cycling dynamics. The mesocosms are located at the Waterman Agricultural and Natural Resources Laboratory on the main campus of The Ohio State University. Four emergent macrophyte functional groups (facultative annuals, obligate annuals, reeds, and tussocks) were chosen to represent a range of plants known to associate closely in natural wetlands and were defined based on physiological, morphological, and life history traits. The functional groups were arranged in a completely random fullfactorial design, for a total of 16 treatments including a no-plant control (n=5). . Three to five 2 cm diameter cores (0-10 cm) were collected randomly from each mesocosm and bulked for analysis. Soils were shipped to The University of New Hampshire, where sub-samples were analyzed for soil moisture, organic matter, pH, and inorganic N content. To determine methane production and iron reduction potentials soils were mixed with deionized water or substrate (200 mM acetate or formate), or deionized water plus an H 2 -CO 2 gas mix (20% H 2 , 5% CO 2 ). A second set of water-only slurries was analyzed immediately for initial reduced iron content using the Ferrozine reagent. Vials were incubated anaerobically and headspace samples were taken four times over an 11 day period and analyzed for CO 2 and CH 4 content. Postincubation a sub-sample from each slurry was analyzed for final reduced iron content. Both methane production and iron reduction potentials were enhanced in the presence of either formate or the H 2 -CO 2 gas mix compared to acetate or water. Cryptic belowground organisms are difficult to observe and their responses to global changes are not well understood. Nevertheless, there is reason to believe that interactions among above-and belowground communities may mediate ecosystem responses to global change. We used grassland mesocosms to manipulate the abundance of one important group of soil organisms, arbuscular mycorrhizal (AM) fungi, and to study community and ecosystem responses to CO 2 and N enrichment. Responses of plants, AM fungi, phospholipid fatty acids (PLFA) and community-level physiological profiles (CLPP) were measured after two growing seasons. Ecosystem responses were examined by measuring net primary production (NPP), evapotranspiration, total soil organic matter (SOM), and extractable mineral N. Structural equation modeling was used to examine the causal relationships among treatments and response variables. We found that while CO 2 and N tended to directly impact ecosystem functions (evapotranspiration and NPP, respectively), AM fungi indirectly impacted ecosystem functions by influencing the community composition of plants and other root fungi, soil fungi and soil bacteria. We found that the mycotrophic status of the dominant plant species in the mesocosms determined whether the presence of AM fungi increased or decreased NPP. Mycotrophic grasses dominated the mesocosm communities during the first growing season, and the mycorrhizal treatments had the highest NPP. In contrast, non-mycotrophic forbs were dominant during the second growing season and the mycorrhizal treatments had the lowest NPP. The composition of the plant community strongly influenced soil N; and the community composition of soil organisms strongly influenced SOM accumulation in the mesocosms. These results show how linkages between above-and belowground communities can determine ecosystem responses to global change. . Paul, MN 55108-6112. Changing resource availability either above-or belowground can alter the structure and function of soil food webs. Understanding how soil food webs respond to long-term carbon dioxide (CO 2 ) and nitrogen (N) enrichment either directly, or indirectly through plant community change, is important for predicting ecosystem responses to these global change factors. Nematode communities can be an excellent indicator of soil food web responses to resource enrichment because community members feed across many trophic levels. We studied responses of nematode feeding guilds to CO 2 and N enrichment in a Free Air CO 2 Enrichment (FACE) experiment at Cedar Creek Ecosystem Science Reserve, MN, USA. Nematode communities were assessed from field samples collected after nine years of treatment with all factorial combinations of ambient and elevated CO 2 (360 or 560 ppm) and ambient or elevated N (0 or 4 g N m -2 ). The overall community structure and abundance of nematodes was not affected by CO 2 or N enrichment. Likewise, no changes were found in the abundance of bacterial feeders, fungal feeders, plant feeders or omnivores. However, there were 50% fewer predators in the elevated CO 2 treatment (p<0.0001). This unexpected result may indicate that either the abundance or quality of preferred prey is impacted by CO 2 enrichment. Vector analysis revealed that the non-metric multidimensional scaling (NMS) axis most strongly related to predator abundance (r=0.45) was aligned with the abundance of arbuscular mycorrhizal fungal (AMF) hyphae (r=0.34), as well as the amount of organic matter (r=-0.21) and N (r=0.21) in the soil. Vectors corresponding to other NMS axes revealed that the nematode trophic community structure was also affected by AMF spore abundance (r=0.27), as well as organic matter (r=-0.24) and soil texture (r=-0.29). Changes in these factors under elevated CO 2 could alter the feeding patterns of nematodes in lower trophic levels and the abundance of particular species within a trophic level, resulting in a non-additive effect on predator abundance. A causal model relating measured biotic and abiotic variables to predatory nematode abundance will be presented. These results demonstrate that CO 2 enrichment can generate indirect effects which influence the structure of soil food webs such that the abundance of predatory nematodes is reduced. Future studies should examine how this change in trophic structure may impact the stability and functioning of soil food webs and consequently ecosystem function. Meloidogyne incognita is a major pest of vegetable crops in Pakistan and has been reported to parasitize most members of the plant kingdom. The purpose of this study was to increase our understanding of host suitability among various vegetable genotypes common to Pakistan. Sixteen crop genotypes of interest came from eight plant families including Apiaceae: carrot Abstracts 303 (Daucus carota) and coriander (Coriandrum sativum); Asteraceae: lettuce (Lactuca sativa); Brassicaceae: cauliflower (Brassica oleracea) and radish (Raphanus sativus); Cruciferae: cabbage (Brassica oleracea) and mustard (Sinapis alba), Cucurbitaceae: bitter gourd (Momordica charantia), Cucumber (Cucumis sativus), pumpkin (Cucurbita argyrosperma), sponge gourd (Luffa cylindrica) and watermelon (Citrullus lanatus); Fabaceae: pea (Pisum sativum); Malvaceae: okra (Abelmoschus esculentus); and Solanaceae: chilies (Capsicum annuum) and eggplant (Solanum melongena) were tested as hosts for M. incognita in a greenhouse. Tomato (Lycopersicon esculentum cv. Money Maker) was included as a susceptible check for comparison. Five seeds of each genotype were planted in 15-cm-diameter clay pots filled with sandy soil. One plant of each genotype was eventually selected for each pot. Each pot was inoculated with 5000 eggs and second-stage juveniles. There were ten replications for each genotype and pots were arranged in completely randomized design on a greenhouse bench maintained at 28 ± 4OC. Host suitability was assessed 60 days after inoculation. Soil and root nematode populations were determined to assess the rate of reproduction [Pf = final population / Pi = initial population]. Roots were evaluated for root galling and egg mass production on 0-5 scale. The roots of all the genotypes produced galls of variable numbers and sizes in response to nematode infection. The gall and egg mass indices and rate of reproduction were also variable among the genotypes. Most resistant to M. incognita were mustard, radish, and cauliflower (< 3 J2/ g root with gall (GI) and egg mass (MI) indices =1). The most susceptible genotypes were bitter gourd, carrot, cucumber, eggplant, lettuce, okra, pea, pumpkin, sponge gourd and watermelon (20 to 350 J2/ g root with GI = 5, and MI = 4). Meanwhile, three plant species including cauliflower, chilies, and coriander provided an intermediate host response. Some plant genotypes appeared to be hypersensitive as they exhibited root galling but suppressed nematode reproduction. These included cabbage, radish, pumpkin, and sponge gourd. The Kona Coffee root-knot nematode (Meloidogyne konaensis) infects coffee grown in the Kona district of Hawaii and reduces yield significantly. Coffea liberica var. dewevrei, Fukunaga is used as a root stock in Hawaii to control nematode. However, identifying new sources of resistance is necessary because of the possibility of nematode virulence against the resistance found in Fukunaga. Semi-wild Ethiopian C. arabica accessions were evaluated to obtain resistance to M. konaensis. Ten genotypes of Ethiopian accessions imported from CATIE, Costa Rica were compared to the well characterized C. arabica cv. Yellow Catuai and C. arabica cv. Typica (susceptible to M. konaensis). M. konaensis eggs were inoculated onto eleven seedlings of each genotype and three seedlings of each genotype received water only. The seedlings were maintained in the greenhouse for 8 months. M. konaensis eggs and J2 were collected from the roots by blending in NaOCl. The number of nematodes in Ethiopian accessions was significantly lower than in the susceptible controls. Nematodes found in Ethiopian accessions were 10 to 15 fold less than in the controls. Ethiopian accessions ET11C, ET15, ET17, ET25, ET28, ET 52, ET 57, ET 25-B and ET 32B showed Rf values <1. These nine Ethiopian accessions can be used as root stock or cultivar, or as a source of resistance for future breeding. THERE IS LITTLE VARIATION IN LIGNOCELLULOSIC FUNGAL COMMUNITY STRUCTURE ON DECOM-POSING WOOD OF TWO SPECIES LIQUIDAMBAR STYRACIFLUA AND PINUS TAEDA ACROSS 3 SITES IN OAK RIDGE, TN. Austin, Emily E. Knoxville, Tennessee. The structure of lignocellulosic fungal communities differs between L. styraciflua and P. taeda wood in the Southeast; this has previously been demonstrated through fruiting body samples. Here I ask the questions: 1) Do fungal communities differ in L. styraciflua and P. taeda trees when measured with molecular techniques such as cloning libraries? And 2) Does the decomposition potential of lignocellulosic fungal communities vary in wood species or site? This study is a pilot for my PhD dissertation project that will focus on wood decomposition, lignocellulosic activity and microbial communities in decomposing wood in their response to environmental changes. We extracted DNA from L. styraciflua and P. taeda stands in adjacent young stands as well as separate stands a few miles away. Eight samples were included, two of each species from each site. Partial cloning libraries were performed on 16s rRNA gene, Large Sub-Unit (LSU) and genes coding for laccase and cellobiohydrolase. While we have observed variation in the fungal community structure, it is not clearly partitioned by site or species. My next project in this area will focus on variation of wood decomposition rates, lignocellulosic activity and microbial communities in decomposing wood of varying decay stage.