Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Hydrofysische gegevens van de bodem in de Basisregistratie Ondergrond (BRO) en het Bodemkundig Informatie Systeem (BIS) : Update 2019
    Bakker, G. ; Heinen, M. ; Gooren, H.P.A. ; Groot, W.J.M. de; Peters, P.D. - \ 2020
    Wageningen : Wettelijke Onderzoekstaken Natuur & Milieu (WOt-technical report 186) - 128
    Soil hydro-physics (SHP) properties are the key properties that determine soil–water interactions. As water is the primary transport medium for dissolved compounds, such as nitrogen, phosphates, pesticides, antibiotics, organic matter, etc., SHP properties are also important for the transport behaviour of these substances. Examples of these properties are water retention, saturated/unsaturated hydraulic conductivity, shrinkage and swelling, organic matter content, texture (particle distribution), structure (soil aggregation/pore structure), density and capillary rise. SHP properties are determinants in research areas related to soil-water conditions: food security (drought and water damage), agricultural development (precision drainage, irrigation), soil salinisation and sodification (evaporation and capillary rise equilibrium), soil greenhouse gas emissions (N2O, CO2), nature conservation (wet and dry ecosystem types), sustainable land use and healthy soils (function allocation), water quality (nutrients, contaminants, antibiotics, percolation, leaching and run-off to groundwater and surface water), flooding and ponding (dike stability, infiltration, soil water repellency) and infrastructural damage (soil shrinkage). Given the increasing demand for current data of high quality and the fact that existing databases lack sufficient potential for upscaling, this project serves as a means to generate additional high quality data each year. The SHP properties and related meta information are implemented in the BIS soil information system and from 2021 will be implemented in the Key Register of the Subsurface (BRO) database as well. Currently there are 240 samples linked to profile descriptions and other meta information in the BIS database.
    Plant community composition steers grassland vegetation via soil legacy effects
    Heinen, Robin ; Hannula, S.E. ; Long, Jonathan R. De; Huberty, Martine ; Jongen, Renske ; Kielak, Anna ; Steinauer, Katja ; Zhu, Feng ; Bezemer, T.M. - \ 2020
    Ecology Letters 23 (2020)6. - ISSN 1461-023X - p. 973 - 982.
    Field experiment - grassland - pathogens - plant-soil feedback - soil bacteria - soil fungi - soil legacy effects - soil microbiome

    Soil legacy effects are commonly highlighted as drivers of plant community dynamics and species co-existence. However, experimental evidence for soil legacy effects of conditioning plant communities on responding plant communities under natural conditions is lacking. We conditioned 192 grassland plots using six different plant communities with different ratios of grasses and forbs and for different durations. Soil microbial legacies were evident for soil fungi, but not for soil bacteria, while soil abiotic parameters did not significantly change in response to conditioning. The soil legacies affected the composition of the succeeding vegetation. Plant communities with different ratios of grasses and forbs left soil legacies that negatively affected succeeding plants of the same functional type. We conclude that fungal-mediated soil legacy effects play a significant role in vegetation assembly of natural plant communities.

    Microbiomes of a specialist caterpillar are consistent across different habitats but also resemble the local soil microbial communities
    Gomes, Sofia I.F. ; Kielak, Anna M. ; Hannula, S.E. ; Heinen, Robin ; Jongen, Renske ; Keesmaat, Ivor ; Long, Jonathan R. De; Bezemer, T.M. - \ 2020
    Animal Microbiome 2 (2020)1. - ISSN 2524-4671
    Background:Insect-associated microorganisms can provide a wide range of benefits to their host, but insectdependency on these microbes varies greatly. The origin and functionality of insect microbiomes is not wellunderstood. Many caterpillars can harbor symbionts in their gut that impact host metabolism, nutrient uptake andpathogen protection. Despite our lack of knowledge on the ecological factors driving microbiome assemblages ofwild caterpillars, they seem to be highly variable and influenced by diet and environment. Several recent studieshave shown that shoot-feeding caterpillars acquire part of their microbiome from the soil. Here, we examinemicrobiomes of a monophagous caterpillar (Tyria jacobaeae) collected from their natural host plant (Jacobaeavulgaris) growing in three different environments: coastal dunes, natural inland grasslands and riverine grasslands,and compare the bacterial communities of the wild caterpillars to those of soil samples collected from underneatheach of the host plants from which the caterpillars were collected.Results:The microbiomes of the caterpillars were dominated by Proteobacteria, Actinobacteria, Firmicutes andBacteroidetes. Only 5% of the total bacterial diversity represented 86.2% of the total caterpillar’s microbiome.Interestingly, we found a high consistency of dominant bacteria within the family Burkholderiaceae in all caterpillarsamples across the three habitats. There was one amplicon sequence variant belonging to the genusRalstoniathatrepresented on average 53% of total community composition across all caterpillars. On average, one quarter of thecaterpillar microbiome was shared with the soil.Conclusions:We found that the monophagous caterpillars collected from fields located more than 100 km apartwere all dominated by a singleRalstonia. The remainder of the bacterial communities that were present resembledthe local microbial communities in the soil in which the host plant was growing. Our findings provide an exampleof a caterpillar that has just a few key associated bacteria, but that also contains a community of low abundantbacteria characteristic of soil communities.
    Above-belowground linkages of functionally dissimilar plant communities and soil properties in a grassland experiment
    Steinauer, Katja ; Heinen, Robin ; Hannula, S.E. ; Long, Jonathan R. De; Huberty, Martine ; Jongen, Renske ; Wang, Minggang ; Bezemer, T.M. - \ 2020
    Ecosphere 11 (2020)9. - ISSN 2150-8925
    nematodes - plant growth rate - soil bacteria - soil fungi - soil microbial respiration - soil nutrients
    Changes in plant community composition can have long-lasting consequences for ecosystem functioning. However, how the duration of plant growth of functionally distinct grassland plant communities influences abiotic and biotic soil properties and thus ecosystem functions is poorly known. In a field experiment, we established identical experimental subplots in two successive years comprising of fast- or slow-growing grass and forb community mixtures with different forb:grass ratios. After one and two years of plant growth, we measured above- and belowground biomass, soil abiotic characteristics (pH, organic matter, soil nutrients), soil microbial properties (respiration, biomass, community composition), and nematode abundance. Fast- and slow-growing plant communities did not differ in above- and belowground biomass. However, fast- and slow-growing plant communities created distinct soil bacterial communities, whereas soil fungal communities differed most in 100% forb communities compared to other forb:grass ratio mixtures. Moreover, soil nitrate availability was higher after two years of plant growth, whereas the opposite was true for soil ammonium concentrations. Furthermore, total nematodes and especially bacterial-feeding nematodes were more abundant after two years of plant growth. Our results show that plant community composition is a driving factor in soil microbial community assembly and that the duration of plant growth plays a crucial role in the establishment of plant community and functional group composition effects on abiotic and biotic soil ecosystem functioning under natural field conditions.
    Exogenous application of plant hormones in the field alters aboveground plant–insect responses and belowground nutrient availability, but does not lead to differences in plant–soil feedbacks
    Heinen, Robin ; Steinauer, Katja ; Long, Jonathan R. De; Jongen, Renske ; Biere, Arjen ; Harvey, Jeffrey A. ; Bezemer, T.M. - \ 2020
    Arthropod-Plant Interactions 14 (2020)5. - ISSN 1872-8855 - p. 559 - 570.
    Field experiment - Herbivory - Insect communities - Jasmonic acid - Plant–soil feedback - Salicylic acid
    Plant–soil feedbacks of plants that are exposed to herbivory have been shown to differ from those of plants that are not exposed to herbivores. Likely, this process is mediated by jasmonic acid (JA) and salicylic acid (SA) defense pathways, which are induced by aboveground herbivory. Furthermore, exogenous application of these phytohormones to plants alters belowground communities, but whether this changes plant–soil feedbacks in natural systems is unknown. We applied exogenous sprays of JA and SA individually and in combination to field plots in a restored grassland. Control plots were sprayed with demineralized water. After three repeated application rounds, we transplanted seedlings of the plant–soil feedback model plant Jacobaea vulgaris as phytometer plants to test the effects of potential phytohormone-mediated changes in the soil, on plant performance during the response phase. We further measured how exogenous application of phytohormones altered plant-related ecosystem characteristics (plot-level); soil chemistry, plot productivity, insect communities and predation. Biomass of the phytometer plants only co-varied with plot productivity, but was not influenced by phytohormone applications. However, we did observe compound-specific effects of SA application on insect communities, most notably on parasitoid attraction, and of JA application on soil nitrogen levels. Although we did not find effects on plant–soil feedbacks, the effects of exogenous application of phytohormones did alter other ecosystem-level processes related to soil nutrient cycling, which may lead to legacy effects in the longer term. Furthermore, exogenous application of phytohormones led to altered attraction of specific insect groups.
    Do plant volatiles confuse rather than guide foraging behavior of the aphid hyperparasitoid Dendrocerus aphidum?
    Boer, Jetske G. de; Hollander, Petra J. ; Heinen, Daan ; Jagger, Divya ; Sliedregt, Pim van; Salis, Lucia ; Kos, Martine ; Vet, Louise E.M. - \ 2020
    Chemoecology (2020). - ISSN 0937-7409
    Associative learning - Fourth trophic level - Herbivore-induced plant volatiles - Host searching - Infochemicals - Microbial volatiles

    Many species of parasitoid wasps use plant volatiles to locate their herbivorous hosts. These volatiles are reliable indicators of host presence when their emission in plants is induced by herbivory. Hyperparasitoids may also use information from lower trophic levels to locate their parasitoid hosts but little is known about the role of volatiles from the plant–host complex in the foraging behavior of hyperparasitoids. Here, we studied how Dendrocerus aphidum (Megaspilidae) responds to plant and host volatiles in a series of experiments. This hyperparasitoid uses aphid mummies as its host and hampers biological control of aphids by parasitoids in greenhouse horticulture. We found that D. aphidum females were strongly attracted to volatiles from mummy-infested sweet pepper plants, but only when clean air was offered as an alternative odor source in the Y-tube olfactometer. Hyperparasitoid females did not have a preference for mummy-infested plants when volatiles from aphid-infested or healthy pepper plants were presented as an alternative. These olfactory responses of D. aphidum were mostly independent of prior experience. Volatiles from the host itself were also highly attractive to D. aphidum, but again hyperparasitoid females only had a preference in the absence of plant volatiles. Our findings suggest that plant volatiles may confuse, rather than guide the foraging behavior of D. aphidum. Mummy hyperparasitoids, such as D. aphidum, can use a wide variety of mummies and are thus extreme generalists at the lower trophic levels, which may explain the limited role of (induced) plant volatiles in their host searching behavior.

    How plant–soil feedbacks influence the next generation of plants
    Long, Jonathan R. De; Heinen, Robin ; Jongen, Renske ; Hannula, S.E. ; Huberty, Martine ; Kielak, Anna M. ; Steinauer, Katja ; Bezemer, T.M. - \ 2020
    Ecological Research (2020). - ISSN 0912-3814
    grassland - maternal effect - plant–soil feedback - seed quality - soil legacies

    In response to environmental conditions, plants can alter the performance of the next generation through maternal effects. Since plant–soil feedbacks (PSFs) influence soil conditions, PSFs likely create such intergenerational effects. We grew monocultures of three grass and three forb species in outdoor mesocosms. We then grew one of the six species, Hypochaeris radicata, in the conditioned soils and collected their seeds. We measured seed weight, carbon and nitrogen concentration, germination and seedling performance when grown on a common soil. We did not detect functional group intergenerational effects, but soils conditioned by different plant species affected H. radicata seed C to N ratios. There was a relationship between parent biomass in the differently conditioned soils and the germination rates of the offspring. However, these effects did not change offspring performance on a common soil. Our findings show that PSF effects changed seed quality and initial performance in a common grassland forb. We discuss the implications of our findings for multi-generational plant–soil interactions, and highlight the need to further explore how PSF effects shape plant community dynamics over different generations and across a broad range of species and functional groups.

    Quantitative comparison between the rhizosphere effect of Arabidopsis thaliana and co-occurring plant species with a longer life history
    Schneijderberg, Martinus ; Cheng, Xu ; Franken, Carolien ; Hollander, Mattias de; Velzen, Robin van; Schmitz, Lucas ; Heinen, Robin ; Geurts, Rene ; Putten, Wim H. van der; Bezemer, Martijn T. ; Bisseling, Ton - \ 2020
    ISME Journal (2020). - ISSN 1751-7362

    As a model for genetic studies, Arabidopsis thaliana (Arabidopsis) offers great potential to unravel plant genome-related mechanisms that shape the root microbiome. However, the fugitive life history of this species might have evolved at the expense of investing in capacity to steer an extensive rhizosphere effect. To determine whether the rhizosphere effect of Arabidopsis is different from other plant species that have a less fugitive life history, we compared the root microbiome of Arabidopsis to eight other, later succession plant species from the same habitat. The study included molecular analysis of soil, rhizosphere, and endorhizosphere microbiome both from the field and from a laboratory experiment. Molecular analysis revealed that the rhizosphere effect (as quantified by the number of enriched and depleted bacterial taxa) was ~35% lower than the average of the other eight species. Nevertheless, there are numerous microbial taxa differentially abundant between soil and rhizosphere, and they represent for a large part the rhizosphere effects of the other plants. In the case of fungal taxa, the number of differentially abundant taxa in the Arabidopsis rhizosphere is 10% of the other species’ average. In the plant endorhizosphere, which is generally more selective, the rhizosphere effect of Arabidopsis is comparable to other species, both for bacterial and fungal taxa. Taken together, our data imply that the rhizosphere effect of the Arabidopsis is smaller in the rhizosphere, but equal in the endorhizosphere when compared to plant species with a less fugitive life history.

    Waterretentie- en doorlatendheidskarakteristieken van boven- en ondergronden in Nederland: de Staringreeks : Update 2018
    Heinen, M. ; Bakker, G. ; Wösten, J.H.M. - \ 2020
    Wageningen : Wageningen Environmental Research (Wageningen Environmental Research rapport 2978) - 77
    In 2001 the first complete database of soil physical properties, water retention and hydraulic conductivity, of 18 top soils and 18 subsoils of the Netherlands was published. This database, known as the Staring series, provides a full coverage of soil horizons for all of the soil units on the Dutch soil map 1:50 000. In the period 2012-2018 new soil samples have been added to the database and an update of the mean retention and conductivity parameters has been realized: Staring series, update 2018.
    International scientists formulate a roadmap for insect conservation and recovery
    Harvey, Jeffrey A. ; Heinen, Robin ; Armbrecht, Inge ; Basset, Yves ; Baxter-Gilbert, James H. ; Bezemer, T.M. ; Böhm, Monika ; Bommarco, Riccardo ; Borges, Paulo A.V. ; Cardoso, Pedro ; Clausnitzer, Viola ; Cornelisse, Tara ; Crone, Elizabeth E. ; Dicke, Marcel ; Dijkstra, Klaas Douwe B. ; Dyer, Lee ; Ellers, Jacintha ; Fartmann, Thomas ; Forister, Mathew L. ; Furlong, Michael J. ; Garcia-Aguayo, Andres ; Gerlach, Justin ; Gols, Rieta ; Goulson, Dave ; Habel, Jan Christian ; Haddad, Nick M. ; Hallmann, Caspar A. ; Henriques, Sérgio ; Herberstein, Marie E. ; Hochkirch, Axel ; Hughes, Alice C. ; Jepsen, Sarina ; Jones, T.H. ; Kaydan, Bora M. ; Kleijn, David ; Klein, Alexandra Maria ; Latty, Tanya ; Leather, Simon R. ; Lewis, Sara M. ; Lister, Bradford C. ; Losey, John E. ; Lowe, Elizabeth C. ; Macadam, Craig R. ; Montoya-Lerma, James ; Nagano, Christopher D. ; Ogan, Sophie ; Orr, Michael C. ; Painting, Christina J. ; Pham, Thai Hong ; Potts, Simon G. ; Rauf, Aunu ; Roslin, Tomas L. ; Samways, Michael J. ; Sanchez-Bayo, Francisco ; Sar, Sim A. ; Schultz, Cheryl B. ; Soares, António O. ; Thancharoen, Anchana ; Tscharntke, Teja ; Tylianakis, Jason M. ; Umbers, Kate D.L. ; Vet, Louise E.M. ; Visser, Marcel E. ; Vujic, Ante ; Wagner, David L. ; Wallis DeVries, Michiel F. ; Westphal, Catrin ; White, Thomas E. ; Wilkins, Vicky L. ; Williams, Paul H. ; Wyckhuys, Kris A.G. ; Zhu, Zeng Rong ; Kroon, Hans de - \ 2020
    Nature Ecology & Evolution 4 (2020)4. - ISSN 2397-334X - p. 174 - 176.
    Irrigation, crop stress and drainage reduction under uncertainty: A scenario study
    Mondaca-Duarte, F.D. ; Mourik, S. van; Balendonck, J. ; Voogt, W. ; Heinen, M. ; Henten, E.J. van - \ 2020
    Agricultural Water Management 230 (2020). - ISSN 0378-3774
    Evapotranspiration - Hydraulic conductivity - Monte Carlo - Richards equation - Uncertainty

    Two thirds of human water use is linked to agricultural practices including crop irrigation. Furthermore, excess irrigation leads to drainage problems. For this reason, reduced irrigation strategies need to be implemented to protect water resources. However, low irrigation may lead to crop water stress. A fast and inexpensive way to predict the necessary amount of irrigation required is by a model-based approach. With this approach, it is possible to explore the relation between irrigation, crop water stress and drainage. However, parameter uncertainty can reduce prediction accuracy. Therefore, the aims of this research were: (1) to develop and test a methodology that allows the analysis of uncertainty sources in irrigation strategies (2) to identify how much irrigation can be reduced while maintaining a low risk of crop stress, and (3) to explore the influence of uncertainty in soil parameters and evapotranspiration on model predictions. Results from a realistic case considered in this study indicated that, while maintaining a low risk of crop stress (<1 %), it is possible to reduce drainage (by 88 %) and water use (22 %) for a conventional irrigation strategy. This reduction is dependent on the type of risk aversion strategy and is specific for a case scenario where variations are certain.

    Development and testing of site-specific fertiliser formulations for rice in sub-Saharan Africa
    Leenaars, J.G.B. ; Egmond, F.M. van; Bosch, H. van den; Ruiperez Gonzalez, M. ; Kempen, B. ; Cisse, L. ; Bocar, A. ; Ros, G.H. ; Vries, W. de; Kros, J. ; Heinen, M. ; Walvoort, D.J.J. ; Oort, P.A.J. van; Saito, Kazuki - \ 2019
    - p. 36 - 36.
    Effect bodemfysische data op modelresultaten ... welke onder meer gebruikt worden in besluitvorming
    Heinen, Marius ; Mulder, Martin ; Hack-ten Broeke, Mirjam - \ 2019
    Noodzakelijke indicatoren voor de beoordeling van de gezondheid van Nederlandse landbouwbodems : Selectie van fysische, chemische en biologische indicatoren voor het meten van de bodemgezondheid
    Elsen, Erik van den; Knotters, Martin ; Heinen, Marius ; Römkens, Paul ; Bloem, Jaap ; Korthals, Gerard - \ 2019
    Wageningen : Wageningen Environmental Research (Wageningen Environmental Research rapport 2944) - 81
    A healthy soil is crucial for mankind. In order to be able to assess soil health, soil health must first be quantified. This can be done on the basis of assessing a limited number of physical, chemical and biological indicators. This report describes how, on the basis of literature research, it is determined which indicators are most suitable for determining soil health. The influence of prevailing environmental variables is also described. Finally, five recommendations are made.
    Hydrofysische gegevens van de bodem in de Basisregistratie Ondergrond (BRO) en het Bodemkundig Informatie Systeem (BIS) : Update 2018
    Bakker, G. ; Heinen, M. ; Gooren, H.P.A. ; Groot, W.J.M. de; Assinck, F.B.T. ; Hummelink, E.W.J. - \ 2019
    Wageningen : Wettelijke Onderzoekstaken Natuur & Milieu (WOt-technical report 149) - 118
    Soil Hydro-Physics (SHP) properties are the key properties that determine soil–water interactions. As water is the primary transport medium for dissolved compounds, such as nitrogen, phosphates, pesticides, antibiotics, organicmatter, etc., Therefore SHP-properties are also important for the transport behaviour of these substances. Examplesof these properties are water retention, -(un)saturated hydraulic conductivity, shrinkage and swelling, organic matter content, texture (particle distribution), structure (soil aggregation/pore structure), density and capillary rise.SHP-properties are determinants in research areas related to soil-water conditions: food security (drought andwater damage), agricultural development (precision drainage, irrigation), soil salinisation and sodification(evaporation and capillary rise equilibrium), soil greenhouse gas emissions (N2O, CO2), nature conservation (wet and dry ecosystem types), sustainable land use and healthy soils (function allocation), water quality (nutrients,contaminants, antibiotics, percolation, leaching and run-off to groundwater and surface water), flooding and ponding (dike stability, infiltration, soil water repellency) and infrastructural damage (soil shrinkage). Given the increasing demand for current data of high quality and the fact that existing databases lack sufficient potential for upscaling, this project serves as a means to generate additional high quality data each year. The SHP-properties and related meta information are implemented in the BIS (Bodem Informatie Systeem) and from 2019 will be implemented in the BRO database (Basisregistratie Ondergrond) as well. Currently there are 217 samples linked toprofile descriptions and other meta information in the BIS-database.
    Quantitative land evaluation implemented in Dutch water management
    Hack-ten Broeke, M.J.D. ; Mulder, H.M. ; Bartholomeus, R.P. ; Dam, J.C. van; Holshof, G. ; Hoving, I.E. ; Walvoort, D.J.J. ; Heinen, M. ; Kroes, J.G. ; Bakel, P.J.T. van; Supit, I. ; Wit, A.J.W. de; Ruijtenberg, R. - \ 2019
    Geoderma 338 (2019). - ISSN 0016-7061 - p. 536 - 545.
    Agro-hydrology - Crop yield assessment - Land use - Meta-model - Simulation modelling - Soil management

    Both in land evaluation and in water management quantitative methods, GIS and simulation modelling are well-known techniques for quantifying the effects of changes, such as land use or climate change. For hydrological management decisions information is often required on the effect of those decisions on agricultural production. To serve the needs of different types of users, like water authorities, provinces, drinking water companies and the National Department of Infrastructure and Water Management we developed a toolbox named WaterVision Agriculture as an instrument that can determine effects on crop yield and the farm economy as a result of drought, too wet or too saline conditions for both current and future climatic conditions. WaterVision Agriculture is based on the hydrological simulation model SWAP, the crop growth model WOFOST and farm management and economic assessments such as DairyWise for dairy farming. The WaterVision Agriculture (WVA) project resulted in two products, namely i) an easily applicable tool (also called the WVA-table) and ii) the operational models for hydrology and crop growth SWAP and WOFOST for calculating effects on field scale combined with calculating farm economic results and indirect effects. SWAP simulates water transport in the unsaturated zone using meteorological data, boundary conditions (like groundwater level or drainage) and soil parameters. WOFOST simulates crop growth as a function of meteorological conditions and crop parameters. Using the combination of these process-based models and methods for describing crop management and economic value we derived a meta-model, i.e. a set of easily applicable simplified relations for assessing crop growth as a function of soil type and groundwater level. These relations are based on multiple model runs for at least 72 soil units and the possible groundwater regimes in the Netherlands. The easily applicable tool (WVA-table) uses this meta-model. Applying the meta-model of WaterVision Agriculture should allow for better decisions on land use or soil and water management because the instrument can help to quantify the effects of changes in climate, land use, hydrological conditions or combinations of these effects on agricultural production.

    Bodemfysica. Tussenrapportage WOT-04-013-006
    Bakker, G. ; Heinen, M. ; Groot, W.J.M. de; Assinck, F.B.T. ; Hummelink, E.W.J. - \ 2018
    WOT Natuur & Milieu (WOt-interne notitie 248)
    Waterwijzer Landbouw : instrumentarium voor kwantificeren van effecten van waterbeheer en klimaat op landbouwproductie
    Mulder, Martin ; Hack-ten Broeke, Mirjam ; Bartholomeus, Ruud ; Dam, Jos van; Heinen, Marius ; Bakel, Jan van; Walvoort, Dennis ; Kroes, Joop ; Hoving, Idse ; Holshof, Gertjan ; Schaap, Joris ; Spruijt, Joanneke ; Supit, Iwan ; Wit, Allard de; Hendriks, Rob ; Haan, Janjo de; Voort, Marcel van der; Walsum, Paul van - \ 2018
    Amersfoort : Stowa (Stowa rapport 2018-48) - ISBN 9789057738128 - 71
    Ant-like Traits in Wingless Parasitoids Repel Attack from Wolf Spiders
    Harvey, Jeffrey A. ; Visser, Bertanne ; Lammers, Marl ; Marien, Janine ; Gershenzon, Jonathan ; Ode, Paul J. ; Heinen, Robin ; Gols, Rieta ; Ellers, Jacintha - \ 2018
    Journal of Chemical Ecology 44 (2018)10. - ISSN 0098-0331 - p. 894 - 904.
    Batesian mimicry; Müllerian mimicry - Chemical defense - Formica - Gelis - Hymenoptera - Lasius - Predation

    A recent study showed that a wingless parasitoid, Gelis agilis, exhibits a suite of ant-like traits that repels attack from wolf spiders. When agitated, G. agilis secreted 6-methyl-5-hepten-2-one (sulcatone), which a small number of ant species produce as an alarm/panic pheromone. Here, we tested four Gelis parasitoid species, occurring in the same food chain and microhabitats, for the presence of sulcatone and conducted two-species choice bioassays with wolf spiders to determine their degree of susceptibility to attack. All four Gelis species, including both winged and wingless species, produced sulcatone, whereas a closely related species, Acrolyta nens, and the more distantly related Cotesia glomerata, did not. In two-choice bioassays, spiders overwhelmingly rejected the wingless Gelis species, preferring A. nens and C. glomerata. However, spiders exhibited no preference for either A. nens or G. areator, both of which are winged. Wingless gelines exhibited several ant-like traits, perhaps accounting for the reluctance of spiders to attack them. On the other hand, despite producing sulcatone, the winged G. areator more closely resembles other winged cryptines like A. nens, making it harder for spiders to distinguish between these two species. C. glomerata was also preferred by spiders over A. nens, suggesting that other non-sulcatone producing cryptines nevertheless possess traits that make them less attractive as prey. Phylogenetic reconstruction of the Cryptinae reveals that G. hortensis and G. proximus are ‘sister’species, with G. agilis, and G.areator in particular evolving along more distant trajectories. We discuss the possibility that wingless Gelis species have evolved a suite of ant-like traits as a form, of mimicry to repel predators on the ground.

    Review of the methodologies used to derive groundwater characteristics for a specific area in The Netherlands
    Ritzema, H.P. ; Heuvelink, G.B.M. ; Heinen, M. ; Bogaart, P.W. ; Bolt, F.J.E. van der; Hack-ten Broeke, M.J.D. ; Hoogland, T. ; Knotters, M. ; Massop, H.T.L. ; Vroon, H.R.J. ; Bosch, H. van den - \ 2018
    Geoderma Regional 14 (2018). - ISSN 2352-0094
    Hydropedology - In-situ measurements - Phreatic groundwater table - Spatial interpolation - Temporal aggregation

    In this paper, we analyze the methods that are used in The Netherlands to upscale in-situ groundwater measurements in time and in space, and how the selected combinations of upscaling methods affect the resulting groundwater characteristic. In The Netherlands, a three-step approach is used to obtain groundwater characteristics for a specific area: (1) in-situ monitoring of the water table depth; (2) temporal upscaling; and (3) spatial interpolation and aggregation. The three-step approach is, however, not standardized, but a combination of the following methods is used: (i) four methods to measure/monitor the phreatic water table; (ii) four methods for temporal aggregation; and (iii) four methods for spatial interpolation and/or aggregation. Over the past sixty years, several combinations of these methods have been used. Our review shows that the use of these different combinations in the approach to measure and interpret water table depths has resulted in significant systematic differences in the corresponding groundwater characteristics and that there are many sources of potential error. Error in the in-situ measurement of the water table depth can be as high as 1 m. Errors in the temporal aggregation are in the range of 10 to 20 cm and for the spatial interpolation between 20 and 50 cm. We show that there has been no systematic assessment of how these errors influence the resulting groundwater characterization. Thus, we cannot answer the question of whether drought stress in The Netherlands is under- or overestimated. Based on these findings we give recommendations for a systematic approach to groundwater characterizations studies that can minimize the impact of errors.

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