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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    Does input of rich litter facilitate tree growth? : growth and climate growth response of oak (Quercus robur) growing in the neighborhood of black cherry (Prunus serotina)
    Haas, Josephine ; Sass Klaassen, Ute ; Akhmetzyanov, Linar ; Ouden, Jan den - \ 2020
    Wageningen : Wageningen University and Research Forest Ecology and Management group - 45
    Atmospheric nitrogen deposition and former land use have led to widespread acidification of forest soils and disturbed nutrient balances, which has been linked to reduced forest vitality and tree growth. The admixture of rich-litter tree species in forests dominated by poor-litter species that further accelerate soil acidification may alleviate the impact of soil acidification on poor sandy soils. Admixture of litter with high base cation content has a positive impact on topsoil pH, as well as base saturation and may potentially affect growth and vitality of trees. To date, the effect of introducing rich-litter species on the long-term growth of co-occurring tree species has not been systematically studied. In this study, we aimed to evaluate the effect of the rich-litter species Prunus serotina on the growth of the poor-litter tree species Quercus robur by means of dendrochronology. We hypothesized that the presence of Prunus will – through soil amelioration - positively affect both the growth and the drought susceptibility of Quercus. We investigated the growth of co-occurring Quercus and Prunus trees in six forest sites with sandy, poor soils in the Netherlands and Germany. We compared tree-ring patterns of oaks growing next to cherry trees (influenced), oaks growing next to other oaks (uninfluenced) and the cherry trees. Tree-ring widths were analyzed on (a) average annual growth variation and basal area increment; (b) the climate sensitivity of the annual growth; (c) the growth response to selected drought years; and (d) the tree-individual growth variation. For most analyses, influenced and uninfluenced oaks showed little differences. Individual growth variation between oaks did show a division between influenced and uninfluenced trees in some sites. However, this division seemed to be linked to spatial separation rather than rich-litter effects. Overall, this study indicated that there is no clear evidence for a facilitating effect of prunus on the growth of oak. It is likely that the studied sites were too poor to capture an effect of the improved soil conditions on the growth of oak, or that competition for water may have overruled any direct soil effect by prunus. We conclude that this study did not provide evidence the rich litter species Prunus serotina does positively affect the growth of Quercus robur on the studied acidic poor sandy soils.---Atmosferische stikstofdepositie en voormalig landgebruik hebben geleid tot een sterke verzuring van bosbodems en verstoorde nutriëntenbalansen, wat in verband wordt gebracht met een verminderde vitaliteit en groei van bomen. Bovendien worden de bossen gedomineerd door boomsoorten met slecht verteerbaar strooisel, waardoor de verzuring van de bodem verder versnelt. Om de impact van bodemverzuring op arme zandgronden te verzachten wordt nu gewerkt aan het (her)introduceren van boomsoorten met goed verteerbaar strooisel in bossen. Bijmenging van strooisel met een hoog gehalte aan basische kationen (met name calcium, kalium, magnesium) heeft een positieve invloed op de pH van de bovengrond, evenals op de base-verzadiging en kan mogelijk de groei en vitaliteit van bomen positief beïnvloeden. Tot op heden is het effect van het introduceren van rijk-strooiselsoorten op de groei van bomen nauwelijks bestudeerd. In deze studie is het effect bestudeerd van de aanwezigheid van de rijk-strooiselsoort Amerikaanse vogelkers (Prunus serotina) op de groei van de zomereik (Quercus robur) met behulp van jaarringanalyse. Onze hypothese was dat de aanwezigheid van Prunus - door bodemverbetering - zowel de groei als de droogtegevoeligheid van Quercus positief zal beïnvloeden. We onderzochten de groei van naast elkaar voorkomende Quercus en Prunus bomen in zes bosgebieden op arme droge zandgronden in Nederland en Duitsland. We vergeleken de jaarringpatronen van eiken die naast vogelkersen groeiden (‘beïnvloed’) met die van eiken die te midden van andere eiken groeiden (‘niet beïnvloed’) en met die van de vogelkersen. Jaarringbreedtes werden geanalyseerd op (a) de gemiddelde jaarlijkse groeivariatie en grondvlakbijgroei; (b) de klimaatgevoeligheid van de jaarlijkse groei; (c) de groeirespons op geselecteerde droogtejaren; en (d) de patronen in groeivariatie in individuele bomen. De meeste analyses toonden aan dat er weinig verschillen zijn in groei tussen beïnvloede en niet-beïnvloede eiken. Op sommige locaties werd wel een verschil gevonden in de jaarlijkse fluctuaties in jaarringbreedtes tussen individuele beïnvloede en niet-beïnvloede eiken, maar dit leek eerder verband te houden met de ruimtelijke scheiding tussen de twee groepen op de betreffende locaties dan met rijk-strooiseleffecten. Over het algemeen geeft deze studie aan dat er geen duidelijk bewijs is voor een faciliterend effect van vogelkers op de groei van eiken. Mogelijk waren de bestudeerde locaties te arm om een effect van de verbeterde bodemgesteldheid op de groei van eiken te veroorzaken ef was vogelkers te kort aanwezig om een duidelijke invloed te hebben op de standplaatskwaliteit. Het is ook mogelijk dat mogelijk positieve effecten van bijmenging met vogelkers werden gemaskeerd door negatieve effecten als gevolg van concurrentie om water. We concluderen dat deze studie geen bewijs leverde dat de rijk-strooiselsoort Prunus serotina een positieve invloed heeft op de groei van Quercus robur op de bestudeerde zure arme zandgronden.
    Efficacy of management and monitoring methods to prevent post‐harvest losses caused by rodents
    Krijger, Inge M. ; Gort, Gerrit ; Belmain, Steven R. ; Groot Koerkamp, Peter ; Shafali, Rokeya B. ; Meerburg, Bastiaan G. - \ 2020
    Animals 10 (2020)9. - ISSN 2076-2615 - p. 1 - 19.
    Bandicota bengalensis - Grain store - Post‐harvest losses - Rattus rattus - Rice - Rodent management

    The presence of pest rodents around food production and storage sites is one of many underlying problems contributing to food contamination and loss, particularly influencing food and nutrition security in low‐income countries. By reducing both pre‐ and post‐harvest losses by rodents, millions of food‐insecure people would benefit. As there are limited quantitative data on post‐harvest rice losses due to rodents, our objectives were to assess stored rice losses in local households from eight rural communities and two rice milling factories in Bangladesh and to monitor the effect of different rodent control strategies to limit potential losses. Four treatments were applied in 2016 and 2017, (i) untreated control, (ii) use of domestic cats, (iii) use of rodenticides, (iv) use of snap‐traps. In total, over a two‐year period, 210 rodents were captured from inside people’s homes, with Rattus rattus trapped most often (n = 91), followed by Mus musculus (n = 75) and Bandicota bengalensis (n = 26). In the milling stations, 68 rodents were trapped, of which 21 were M. musculus, 19 R. rattus, 17 B. bengalensis, 8 Rattus exulans, and 3 Mus terricolor. In 2016, losses from standardised baskets of rice within households were between 13.6% and 16.7%. In 2017, the losses were lower, ranging from 0.6% to 2.2%. Daily rodent removal by trapping proved to be most effective to diminish stored produce loss. The effectiveness of domestic cats was limited.

    Potential sources of bias in the climate sensitivities of fish otolith biochronologies
    Smoliński, Szymon ; Morrongiello, John ; Sleen, Peter Van Der; Black, Bryan A. ; Campana, Steven E. - \ 2020
    Canadian Journal of Fisheries and Aquatic Sciences 77 (2020)9. - ISSN 0706-652X - p. 1552 - 1563.

    Analysis of growth increments in the hard parts of animals (e.g., fish otoliths) can be used to assess how organisms respond to variability in environmental conditions. In this study, mixed-effects models were applied to otolith data simulated for two hypothetical fish populations with assumed biological parameters and known growth response to environmental variability. Our objective was to assess the sensitivity of environment-growth relationships derived from otolith biochronologies when challenged with a range of realistic ageing errors and sampling regimes. We found that the development of a robust biochronology and the precision of environmental effect estimates can be seriously hampered by insufficient sample size. Moreover, the introduction of even moderate ageing error into the data can cause substantial underestimation of environmental sources of growth variation. This underestimation diminished our capacity to correctly quantify the known environment-growth relationship and more generally will lead to overly conservative conclusions concerning the growth response to environmental change. Careful study design, reduction of ageing errors, and large sample sizes are critical prerequisites if robust inferences are to be made from biochronological data.

    SEVA 3.1: enabling interoperability of DNA assembly among the SEVA, BioBricks and Type IIS restriction enzymes standards
    Damalas, S. ; Batianis, C. ; Martin Pascual, Maria ; Lorenzo, V. de; Martins dos Santos, V.A.P. - \ 2020
    Microbial Biotechnology (2020). - ISSN 1751-7907
    Robust synthetic biology applications rely heavily on the design and assembly of DNA parts with specific functionalities based on engineering principles. However, the assembly standards adopted by different communities vary considerably, thus limiting the interoperability of parts, vectors and methods. We hereby introduce the SEVA 3.1 platform consisting of the SEVA 3.1 vectors and the Golden Gate‐based ‘SevaBrick Assembly’. This platform enables the convergence of standard processes between the SEVA platform, the BioBricks and the Type IIs‐mediated DNA assemblies to reduce complexity and optimize compatibility between parts and methods. It features a wide library of cloning vectors along with a core set of standard SevaBrick primers that allow multipart assembly and exchange of short functional genetic elements (promoters, RBSs) with minimal cloning and design effort. As proof of concept, we constructed, among others, multiple sfGFP expression vectors under the control of eight RBSs, eight promoters and four origins of replication as well as an inducible four‐gene operon expressing the biosynthetic genes for the black pigment proviolacein. To demonstrate the interoperability of the SEVA 3.1 vectors, all constructs were characterized in both Pseudomonas putida and Escherichia coli. In summary, the SEVA 3.1 platform optimizes compatibility and modularity of inserts and backbones with a cost‐ and time‐friendly DNA assembly method, substantially expanding the toolbox for successful synthetic biology applications in Gram‐negative bacteria.
    Learning to Become an FSC Auditor: Objectivity, Interpretation, and Mastery
    Cook, W.C. ; Turnhout, E. ; Bommel, S. van - \ 2020
    Science and Technology Studies 33 (2020)2. - ISSN 2243-4690 - p. 32 - 48.
    This paper aims to open the black box of auditing for the Forest Stewardship Council (FSC) forest management standard. Specifically, we delve into the early steps of becoming an FSC auditor by examining two auditor training sessions in northern Europe.
    Using a mix of participant observation and unstructured interviews, the paper subjects the trainings to a dramaturgical analysis that focuses on the ways in which objectivity was performed and on how it was taught to be performed.
    Alongside being an exploratory piece on FSC auditor training, this article highlights how objectivity and subjectivity are co-supportive components. Instead of being something to shy away from, auditors are implicitly taught the values of auditing even if they compromise the objective claims of the auditing process. Furthermore, the paper establishes that both interpretive and objective aspects are necessary, and that to compromise either is to diminish the capacity of the audit process.
    Lake trout growth is sensitive to spring temperature in southwest Alaska lakes
    Biela, Vanessa R. von; Black, Bryan A. ; Young, Daniel B. ; Sleen, Peter van der; Bartz, Krista K. ; Zimmerman, Christian E. - \ 2020
    Ecology of Freshwater Fish (2020). - ISSN 0906-6691
    biochronology - growth - lake trout - marine-derived nutrients - Pacific salmon - temperature

    In high-latitude lakes, air temperature is an important driver of ice cover thickness and duration, which in turn influence water temperature and primary production supporting lake consumers and predators. In lieu of multidecadal observational records necessary to assess the response of lakes to long-term warming, we used otolith-based growth records from a long-lived resident lake fish, lake trout (Salvelinus namaycush), as a proxy for production. Lake trout were collected from seven deep, oligotrophic lakes in Lake Clark National Park and Preserve on in southwest Alaska that varied in the presence of marine-derived nutrients (MDN) from anadromous sockeye salmon (Oncorhynchus nerka). Linear mixed-effects models were used to partition variation in lake trout growth by age and calendar-year and model comparisons tested for a mean increase in lake trout growth with sockeye salmon presence. Year effects from the best mixed-effects model were subsequently compared to indices of temperature, lake ice, and regional indices of sockeye salmon escapement. A strong positive correlation between annual lake trout growth and temperature suggested that warmer springs, earlier lake ice break-up, and a longer ice-free growing season increase lake trout growth via previously identified bottom-up increases in production with warming. Accounting for differences in the presence or annual escapement of sockeye salmon with available data did not improve model fit. Collectively with other studies, the results suggest that productivity of subarctic lakes has benefitted from warming spring temperatures and that temperature can synchronise otolith growth across lakes with and without sockeye salmon MDN.

    Rethinking organic wastes bioconversion: Evaluating the potential of the black soldier fly (Hermetia illucens (L.)) (Diptera: Stratiomyidae) (BSF)
    Surendra, K.C. ; Tomberlin, Jeffery K. ; Huis, Arnold van; Cammack, Jonathan A. ; Heckmann, Lars Henrik L. ; Khanal, Samir Kumar - \ 2020
    Waste Management 117 (2020). - ISSN 0956-053X - p. 58 - 80.
    Bioactive compounds - Biobased products - Bioconversion - Biodiesel - Biorefinery - Black soldier fly - Feed - Organic fertilizer - Organic wastes

    Population growth and unprecedented economic growth and urbanization, especially in low- and middle-income countries, coupled with extreme weather patterns, the high-environmental footprint of agricultural practices, and disposal-oriented waste management practices, require significant changes in the ways we produce food, feed and fuel, and manage enormous amounts of organic wastes. Farming insects such as the black soldier fly (BSF) (Hermetia illucens) on diverse organic wastes provides an opportunity for producing nutrient-rich animal feed, fuel, organic fertilizer, and biobased products with concurrent valorization of wastes. Inclusion of BSF larvae/pupae in the diets of poultry, fish, and swine has shown promise as a potential substitute of conventional feed ingredients such as soybean meal and fish meal. Moreover, the bioactive compounds such as antimicrobial peptides, medium chain fatty acids, and chitin and its derivatives present in BSF larvae/pupae, could also add values to the animal diets. However, to realize the full potential of BSF-based biorefining, more research and development efforts are necessary for scaling up the production and processing of BSF biomass using more mechanized and automated systems. More studies are also needed to ensure the safety of the BSF biomass grown on various organic wastes for animal feed (also food) and legalizing the feed application of BSF biomass to wider categories of animals. This critical review presents the current status of the BSF technology, identifies the research gaps, highlights the challenges towards industrial scale production, and provides future perspectives.

    "Age" determination of European flat oysters from the Voordelta reef
    Witbaard, R. ; Bos, O.G. ; Kamermans, P. - \ 2020
    Texel : NIOZ Royal Institute for Sea Research (NIOZ Report 2020-01) - 29 p.
    Based on the earlier studies and the appearance of the growth lines, the indicative size-age relationship which evolved from counts of the lines, it is likely that the counted lines are annual in nature. Age at size matches to relationships found for a UK population (Essex-Black River). If this assumption is true, it means that the 14 year old shell (#006) which was collected in December 2015 must have settled in the period 2001-2002, depending on the exact timing of line formation. In this study 12 shells were analyzed. Assuming annual growth lines, any shell collected in 2015 older than 7 years (i.e., 2 shells), or collected in 2017 and older than 9 years (i.e., 3 shells) would have been present before 2008, that is, before designation of the Natura 2000 site Voordelta in 2008. The results show that this is the case for 5 out of 12 of the analyzed shells. This leads to the conclusion that at the moment of Natura 2000 site designation, the oyster bed probably was already present to some extent.
    Making Scale Work for Sustainable Development : A Framework for Responsible Scaling of Agricultural Innovations
    Wigboldus, S.A. ; Klerkx, L.W.A. ; Leeuwis, C. - \ 2020
    In: Science, Technology, and Innovation for Sustainable Development Goals / Adenle, A.A., Chertow, M.R., Moors, E.H.M., Pannell, D.J., New York : Oxford University Press - ISBN 9780190949501 - p. 518 - 543.
    Scaling generalizable solutions delivered through science, technology, and innovation has become a dominant paradigm for achieving the sustainable development goals. In many cases, organizations articulate theories of change that are intended to support the strategic design and guidance of agricultural research and innovation to contribute to impact at scale. How scaling beyond the immediate research and innovation context is expected to happen, however, is often poorly elaborated in theories of change. The question of how scaling could happen—that is, a theory of scaling—tends to remain a black box of unarticulated assumptions. Similarly, policymakers often lack a governance sense-making framework to consider the appropriateness of a multitude of scaling initiatives in light of societal goals. Recent studies have drawn attention to the fact that scaling processes involve greater complexity than is generally taken into account. This chapter addresses this situation by unpacking what is in that black box and translating this into a guidance framework along the lines of a theory of scaling as a dedicated component of a wider theory of change. The objective is to support researchers, management decision-makers, and policymakers in engaging more effectively and responsibly with scaling initiatives.
    Removing top leaves increases yield and nutrient uptake in maize plants
    Raza, Muhammad Ali ; Werf, Wopke van der; Ahmed, Mukhtar ; Yang, Wenyu - \ 2020
    Nutrient Cycling in Agroecosystems 118 (2020)1. - ISSN 1385-1314 - p. 57 - 73.
    Maize - Nitrogen - Phosphorus - Potassium - Seed filling-phase

    Abstract: Intraspecific competition for light affects nutrient uptake of maize, especially during the seed filling phase (from the blistering-stage to physiological-maturity). Partial leaf removal only affects the top leaves and improves the light-environment, which could then enhance nutrient uptake during the seed filling phase. However, there is a shortage of quantitative information on the yield effects of such a management measure. A 3-year field trial was conducted to evaluate the impact of different leaf removal treatments (no removal of leaves (D0: control), removal of two leaves (D2), removal of four leaves (D4), and removal of six leaves (D6) from maize-canopy) on total dry matter accumulation, and nitrogen, phosphorus, and potassium uptake at the blistering-stage and physiological-maturity, plus seed number per plant, seed weight, and seed yield at physiological maturity. Compared to D0, at physiological-maturity, D2 significantly increased total dry matter accumulation (by 9%), and uptake of nitrogen (by 5%), phosphorus (by 10%), and potassium (by 4%); while excessive leaf removal treatments considerably reduced dry matter accumulation and nutrient uptake. Importantly, during the seed filling phase of maize, treatment D2 significantly enhanced the uptake of nitrogen, phosphorus, and potassium by 76%, 40%, and 65%, respectively, compared to control. Treatment D2 increased seed number per plant (by 6.4%, from 448 under D0 to 477 in D2) and seed weight (by 5.7%). Relative to control, maize in D2 had 12%, 14%, and 11%, higher seed-yields in 2017, 2018, and 2019, respectively, and it also improved the economic profit when taking into account labor costs. Graphic abstract: Graphical representation of changes in light transmittance, photosynthesis, nutrient uptake, carbohydrate, and dry matter accumulation in maize plants as affected by different leaf removal treatments. Treatment codes represent no defoliation (D0: control), removal of two leaves (D2), removal of four leaves (D4), and removal of six leaves (D6) from the top of maize canopy. Yellow and green arrows show the light environment and leaf area of maize plants. The black arrows represent the regulating directions of leaf removal treatments on maize growth and development in this paper. The graphical abstract clearly demonstrates the significant improvement of optimum leaf removal treatment (D2) as compared to control (D0). The red and blue arrows show the relevant increase and decrease of the mentioned components between the optimal leaf removal and control. [Figure not available: see fulltext.]

    Nutritional composition of black soldier fly larvae feeding on agro-industrial by-products
    Chia, Shaphan Y. ; Tanga, Chrysantus M. ; Osuga, Isaac M. ; Cheseto, Xavier ; Ekesi, Sunday ; Dicke, Marcel ; Loon, Joop J.A. van - \ 2020
    Entomologia Experimentalis et Applicata 168 (2020)6-7. - ISSN 0013-8703 - p. 472 - 481.
    agro industry, bioconversion - animal feed ingredients - black soldier fly - brewers’ spent grain - brewer’s yeast - Diptera - Hermetia illucens - minerals - molasses - nutrition - organic side-streams - protein - Stratiomyidae

    Black soldier fly (BSF) larvae, Hermetia illucens L. (Diptera: Stratiomyidae), bio-convert organic side streams into high-quality biomass, the composition of which largely depends on the side stream used. In the present study, BSF larvae were reared on feed substrates composed of dried brewers’ spent grains, each supplemented with either water, waste brewer’s yeast, or a mixture of waste brewer’s yeast and cane molasses to obtain 12 different substrates: barley/water, barley/yeast, barley/yeast/molasses, malted barley/water, malted barley/yeast, malted barley/yeast/molasses, malted corn/water, malted corn/yeast, malted corn/yeast/molasses, sorghum-barley/water, sorghum-barley/yeast, and sorghum-barley/yeast/molasses. The crude protein, fat, ash, and mineral contents of the BSF larvae fed each feed substrate were quantified by chemical analyses. The effect of substrate, supplementation, and their interaction on crude protein, fat, and ash contents of BSF larval body composition was significant. Calcium, phosphorus, and potassium were the most abundant macrominerals in the larvae and their concentrations differed significantly among substrates. These findings provide important information to support the use of BSF larval meal as potential new source of nutrient-rich and sustainable animal feed ingredients to substitute expensive and scarce protein sources such as fishmeal and soya bean meal.

    The FLUXNET2015 dataset and the ONEFlux processing pipeline for eddy covariance data
    Pastorello, Gilberto ; Trotta, Carlo ; Canfora, Eleonora ; Chu, Housen ; Christianson, Danielle ; Cheah, You Wei ; Poindexter, Cristina ; Chen, Jiquan ; Elbashandy, Abdelrahman ; Humphrey, Marty ; Isaac, Peter ; Polidori, Diego ; Ribeca, Alessio ; Ingen, Catharine van; Zhang, Leiming ; Amiro, Brian ; Ammann, Christof ; Arain, M.A. ; Ardö, Jonas ; Arkebauer, Timothy ; Arndt, Stefan K. ; Arriga, Nicola ; Aubinet, Marc ; Aurela, Mika ; Baldocchi, Dennis ; Barr, Alan ; Beamesderfer, Eric ; Marchesini, Luca Belelli ; Bergeron, Onil ; Beringer, Jason ; Bernhofer, Christian ; Berveiller, Daniel ; Billesbach, Dave ; Black, Thomas Andrew ; Blanken, Peter D. ; Bohrer, Gil ; Boike, Julia ; Bolstad, Paul V. ; Bonal, Damien ; Bonnefond, Jean Marc ; Bowling, David R. ; Bracho, Rosvel ; Brodeur, Jason ; Brümmer, Christian ; Buchmann, Nina ; Burban, Benoit ; Burns, Sean P. ; Buysse, Pauline ; Cale, Peter ; Cavagna, Mauro ; Cellier, Pierre ; Chen, Shiping ; Chini, Isaac ; Christensen, Torben R. ; Cleverly, James ; Collalti, Alessio ; Consalvo, Claudia ; Cook, Bruce D. ; Cook, David ; Coursolle, Carole ; Cremonese, Edoardo ; Curtis, Peter S. ; Andrea, Ettore D'; Rocha, Humberto da; Dai, Xiaoqin ; Davis, Kenneth J. ; Cinti, Bruno De; Grandcourt, Agnes de; Ligne, Anne De; Oliveira, Raimundo C. De; Delpierre, Nicolas ; Desai, Ankur R. ; Bella, Carlos Marcelo Di; Tommasi, Paul di; Dolman, Han ; Domingo, Francisco ; Dong, Gang ; Dore, Sabina ; Duce, Pierpaolo ; Dufrêne, Eric ; Dunn, Allison ; Dušek, Jiří ; Eamus, Derek ; Eichelmann, Uwe ; ElKhidir, Hatim Abdalla M. ; Eugster, Werner ; Ewenz, Cacilia M. ; Ewers, Brent ; Famulari, Daniela ; Fares, Silvano ; Feigenwinter, Iris ; Feitz, Andrew ; Fensholt, Rasmus ; Filippa, Gianluca ; Fischer, Marc ; Frank, John ; Galvagno, Marta ; Gharun, Mana ; Gianelle, Damiano ; Gielen, Bert ; Gioli, Beniamino ; Gitelson, Anatoly ; Goded, Ignacio ; Goeckede, Mathias ; Goldstein, Allen H. ; Gough, Christopher M. ; Goulden, Michael L. ; Graf, Alexander ; Griebel, Anne ; Gruening, Carsten ; Grünwald, Thomas ; Hammerle, Albin ; Han, Shijie ; Han, Xingguo ; Hansen, Birger Ulf ; Hanson, Chad ; Hatakka, Juha ; He, Yongtao ; Hehn, Markus ; Heinesch, Bernard ; Hinko-Najera, Nina ; Hörtnagl, Lukas ; Hutley, Lindsay ; Ibrom, Andreas ; Ikawa, Hiroki ; Jackowicz-Korczynski, Marcin ; Janouš, Dalibor ; Jans, Wilma ; Jassal, Rachhpal ; Jiang, Shicheng ; Kato, Tomomichi ; Khomik, Myroslava ; Klatt, Janina ; Knohl, Alexander ; Knox, Sara ; Kobayashi, Hideki ; Koerber, Georgia ; Kolle, Olaf ; Kosugi, Yoshiko ; Kotani, Ayumi ; Kowalski, Andrew ; Kruijt, Bart ; Kurbatova, Julia ; Kutsch, Werner L. ; Kwon, Hyojung ; Launiainen, Samuli ; Laurila, Tuomas ; Law, Bev ; Leuning, Ray ; Li, Yingnian ; Liddell, Michael ; Limousin, Jean Marc ; Lion, Marryanna ; Liska, Adam J. ; Lohila, Annalea ; López-Ballesteros, Ana ; López-Blanco, Efrén ; Loubet, Benjamin ; Loustau, Denis ; Lucas-Moffat, Antje ; Lüers, Johannes ; Ma, Siyan ; Macfarlane, Craig ; Magliulo, Vincenzo ; Maier, Regine ; Mammarella, Ivan ; Manca, Giovanni ; Marcolla, Barbara ; Margolis, Hank A. ; Marras, Serena ; Massman, William ; Mastepanov, Mikhail ; Matamala, Roser ; Matthes, Jaclyn Hatala ; Mazzenga, Francesco ; McCaughey, Harry ; McHugh, Ian ; McMillan, Andrew M.S. ; Merbold, Lutz ; Meyer, Wayne ; Meyers, Tilden ; Miller, Scott D. ; Minerbi, Stefano ; Moderow, Uta ; Monson, Russell K. ; Montagnani, Leonardo ; Moore, Caitlin E. ; Moors, Eddy ; Moreaux, Virginie ; Moureaux, Christine ; Munger, J.W. ; Nakai, Taro ; Neirynck, Johan ; Nesic, Zoran ; Nicolini, Giacomo ; Noormets, Asko ; Northwood, Matthew ; Nosetto, Marcelo ; Nouvellon, Yann ; Novick, Kimberly ; Oechel, Walter ; Olesen, Jørgen Eivind ; Ourcival, Jean Marc ; Papuga, Shirley A. ; Parmentier, Frans Jan ; Paul-Limoges, Eugenie ; Pavelka, Marian ; Peichl, Matthias ; Pendall, Elise ; Phillips, Richard P. ; Pilegaard, Kim ; Pirk, Norbert ; Posse, Gabriela ; Powell, Thomas ; Prasse, Heiko ; Prober, Suzanne M. ; Rambal, Serge ; Rannik, Üllar ; Raz-Yaseef, Naama ; Reed, David ; Dios, Victor Resco de; Restrepo-Coupe, Natalia ; Reverter, Borja R. ; Roland, Marilyn ; Sabbatini, Simone ; Sachs, Torsten ; Saleska, Scott R. ; Sánchez-Cañete, Enrique P. ; Sanchez-Mejia, Zulia M. ; Schmid, Hans Peter ; Schmidt, Marius ; Schneider, Karl ; Schrader, Frederik ; Schroder, Ivan ; Scott, Russell L. ; Sedlák, Pavel ; Serrano-Ortíz, Penélope ; Shao, Changliang ; Shi, Peili ; Shironya, Ivan ; Siebicke, Lukas ; Šigut, Ladislav ; Silberstein, Richard ; Sirca, Costantino ; Spano, Donatella ; Steinbrecher, Rainer ; Stevens, Robert M. ; Sturtevant, Cove ; Suyker, Andy ; Tagesson, Torbern ; Takanashi, Satoru ; Tang, Yanhong ; Tapper, Nigel ; Thom, Jonathan ; Tiedemann, Frank ; Tomassucci, Michele ; Tuovinen, Juha Pekka ; Urbanski, Shawn ; Valentini, Riccardo ; Molen, Michiel van der; Gorsel, Eva van; Huissteden, Ko van; Varlagin, Andrej ; Verfaillie, Joseph ; Vesala, Timo ; Vincke, Caroline ; Vitale, Domenico ; Vygodskaya, Natalia ; Walker, Jeffrey P. ; Walter-Shea, Elizabeth ; Wang, Huimin ; Weber, Robin ; Westermann, Sebastian ; Wille, Christian ; Wofsy, Steven ; Wohlfahrt, Georg ; Wolf, Sebastian ; Woodgate, William ; Li, Yuelin ; Zampedri, Roberto ; Zhang, Junhui ; Zhou, Guoyi ; Zona, Donatella ; Agarwal, Deb ; Biraud, Sebastien ; Torn, Margaret ; Papale, Dario - \ 2020
    Scientific Data 7 (2020)1. - ISSN 2052-4463 - 1 p.

    The FLUXNET2015 dataset provides ecosystem-scale data on CO2, water, and energy exchange between the biosphere and the atmosphere, and other meteorological and biological measurements, from 212 sites around the globe (over 1500 site-years, up to and including year 2014). These sites, independently managed and operated, voluntarily contributed their data to create global datasets. Data were quality controlled and processed using uniform methods, to improve consistency and intercomparability across sites. The dataset is already being used in a number of applications, including ecophysiology studies, remote sensing studies, and development of ecosystem and Earth system models. FLUXNET2015 includes derived-data products, such as gap-filled time series, ecosystem respiration and photosynthetic uptake estimates, estimation of uncertainties, and metadata about the measurements, presented for the first time in this paper. In addition, 206 of these sites are for the first time distributed under a Creative Commons (CC-BY 4.0) license. This paper details this enhanced dataset and the processing methods, now made available as open-source codes, making the dataset more accessible, transparent, and reproducible.

    Digest: How the snowshoe hare got its brown coat: Convergent evolution or gene flow?*
    Ottenburghs, Jente - \ 2020
    Evolution (2020). - ISSN 0014-3820

    The winter-brown phenotype of snowshoe hares in the Pacific Northwest was acquired through hybridization with black-tailed jackrabbits. Some snowshoe hares in more northern boreal populations exhibit the same phenotype, but how did they acquire it? Jones and colleagues show that the phenotype in the boreal populations is the outcome of convergent evolution, highlighting the importance of understanding the genetic basis of a trait in reconstructing its evolution.

    Insights in the Global Genetics and Gut Microbiome of Black Soldier Fly, Hermetia illucens: Implications for Animal Feed Safety Control
    Khamis, Fathiya M. ; Ombura, Fidelis L.O. ; Akutse, Komivi S. ; Subramanian, Sevgan ; Mohamed, Samira A. ; Fiaboe, Komi K.M. ; Saijuntha, Weerachai ; Loon, Joop J.A. Van; Dicke, Marcel ; Dubois, Thomas ; Ekesi, Sunday ; Tanga, Chrysantus M. - \ 2020
    Frontiers in Microbiology 11 (2020). - ISSN 1664-302X
    16S-metagenomics - genetic diversity - gut microbiome - Hermetia illucens - mitochondrial COI gene

    The utilization of the black soldier fly (BSF) Hermetia illucens L. for recycling organic waste into high-quality protein and fat biomass for animal feeds has gained momentum worldwide. However, information on the genetic diversity and environmental implications on safety of the larvae is limited. This study delineates genetic variability and unravels gut microbiome complex of wild-collected and domesticated BSF populations from six continents using mitochondrial COI gene and 16S metagenomics. All sequences generated from the study linked to H. illucens accessions KM967419.1, FJ794355.1, FJ794361.1, FJ794367.1, KC192965.1, and KY817115.1 from GenBank. Phylogenetic analyses of the sequences generated from the study and rooted by GenBank accessions of Hermetia albitarsis Fabricius and Hermetia sexmaculata Macquart separated all samples into three branches, with H. illucens and H. sexmaculata being closely related. Genetic distances between H. illucens samples from the study and GenBank accessions of H. illucens ranged between 0.0091 and 0.0407 while H. sexmaculata and H. albitarsis samples clearly separated from all H. illucens by distances of 0.1745 and 0.1903, respectively. Genetic distance matrix was used to generate a principal coordinate plot that further confirmed the phylogenetic clustering. Haplotype network map demonstrated that Australia, United States 1 (Rhode Island), United States 2 (Colorado), Kenya, and China shared a haplotype, while Uganda shared a haplotype with GenBank accession KC192965 BSF from United States. All other samples analyzed had individual haplotypes. Out of 481,695 reads analyzed from 16S metagenomics, four bacterial families (Enterobactereaceae, Dysgonomonadaceae, Wohlfahrtiimonadaceae, and Enterococcaceae) were most abundant in the BSF samples. Alpha-diversity, as assessed by Shannon index, showed that the Kenyan and Thailand populations had the highest and lowest microbe diversity, respectively; while microbial diversity assessed through Bray Curtis distance showed United States 3 (Maysville) and Netherlands populations to be the most dissimilar. Our findings on genetic diversity revealed slight phylogeographic variation between BSF populations across the globe. The 16S data depicted larval gut bacterial families with economically important genera that might pose health risks to both animals and humans. This study recommends pre-treatment of feedstocks and postharvest measures of the harvested BSF larvae to minimize risk of pathogen contamination along the insect-based feed value chain.

    Plant responses to insect eggs are not induced by egg-associated micorbes, but by a secretion attached to the eggs.
    Paniagua, L. ; Valsamakis, Georgios ; Lortzing, Vivien ; Weinhold, Arne ; Johnston, P. ; Fatouros, N.E. ; Kunze, R. ; Hilker, M. - \ 2020
    Plant, Cell & Environment 43 (2020)8. - ISSN 0140-7791 - p. 1815 - 1826.
    Plants can enhance their defence against herbivorous insects by responding to insect egg depositions preceding larval feeding. The similarity of plant responses to insect eggs with those to phytopathogens gave rise to the hypothesis that egg‐associated microbes might act as elicitors. We tested this hypothesis by investigating first if elimination of microbes in the butterfly Pieris brassicae changes the responses of Brassica nigra and Arabidopsis thaliana to eggs and larvae of this insect species. An antibiotic treatment of butterflies mitigated the plant transcriptional response to the eggs and the egg‐mediated enhancement of the plant′s defence against larvae. However, application of cultivated microbial isolates from the eggs onto A. thaliana did not enhance the plant′s anti‐herbivore defence. Instead, application of an egg‐associated glandular secretion, which is attaching the eggs to the leaves, elicited the enhancing effect on the plant′s defence against larvae. However, this effect was only achieved when the secretion was applied in similar quantities as released by control butterflies, but not when applied in the reduced quantity as released by antibiotic‐treated butterflies. We conclude that glandular secretions rather than egg‐associated microbes act in a dose‐dependent manner as elicitor of the egg‐mediated enhancement of the plant′s defence against insect larvae.
    Litter share and clay content determine soil restoration effects of rich litter tree species in forests on acidified sandy soils
    Desie, Ellen ; Vancampenhout, Karen ; Berg, Leon van den; Nyssen, Bart ; Weijters, Maaike ; Ouden, Jan den; Muys, Bart - \ 2020
    Forest Ecology and Management 474 (2020). - ISSN 0378-1127
    Black cherry - Clay content - Litter quality - Nutrient cycling - Soil acidification - Soil restoration

    Many West-European forests are located on degraded and acidified soils. Soil acidification has resulted in hampered ecosystem functioning and lower delivery of ecosystem services. Forest management, particularly the choice of tree species, can accelerate or counteract soil acidification by the quality of litter input. The positive impact of so called ‘rich litter’ on the soil nutrient status and belowground ecosystem functioning has already been evidenced in common gardens. Here, we evaluate the effect of the rich litter species black cherry (Prunus serotina Ehrh.) in mixed forest stands dominated by pedunculate oak (Quercus robur L.). We study the effects using a replicated set-up of 10 established forest stands (age 30 to 90) in Belgium, the Netherlands and Germany along an edaphic gradient in sandy soils on Pleistocene aeolian deposits. We hypothesize that black cherry has a positive effect on the soil nutrient status and aim to answer the following research questions: (i) does admixture of black cherry increase soil pH and base saturation? (ii) what proportion of rich litter admixture is needed in a poor litter matrix to observe significant improvement of the soil nutrient status? and (iii) does the magnitude of the rich litter effect interact with initial soil properties? The results of this study indicate that admixture of black cherry enhances the forest floor turnover and enriches topsoil chemical conditions significantly. Thickness of the litter layer decreases from a mean of 7 cm under oak to a mean of 4.5 cm under cherry and correspondingly base saturation increases to a maximum of 25%, NO3 concentration to 26 mg/mg and organic matter content to 8%. However, large shares of rich litter admixture (>30% basal area) are needed to improve topsoil conditions. Moreover, we find that rich litter effects are more pronounced on sandy soils with higher fine particle (loam + clay) content. This suggests that the actual impact of restoration efforts in acidified forest soils is a product of the trinity “litter quality – litter share – site quality”.

    Mechanical and Enzyme Assisted Fractionation Process for a Sustainable Production of Black Soldier Fly (Hermetia illucens) Ingredients
    Azzollini, Domenico ; Iwaarden, Amber van; Lakemond, Catriona M.M. ; Fogliano, Vincenzo - \ 2020
    Frontiers in Sustainable Food Systems 4 (2020). - ISSN 2571-581X
    alcalase - Bio-fractionation - Black soldier fly - Edible insects - mechanical pressing

    This study aimed at effective fractionation of Hermetia illucens into lipid and protein, considering the insects' anatomy. A hybrid approach was developed, separating the exoskeleton by mechanical pressing and fractionating the slurry by sonication and enzymatic treatment. Microscopy showed that the peripheral fat bodies were tightly attached to muscle fibers. Blanching caused protein aggregation and entrapment of fat in the protein matrix, resulting in 25.0% loss in fat extraction, compared to only 3.3% loss for unblanched larvae. After centrifugation of the juice obtained from unblanched larvae a cream layer rich of lipids and proteins, a supernatant with soluble protein, and a pellet including mainly insoluble proteins were obtained. Blanched juice centrifugation formed a lipid fraction, a reduced cream layer, and more pellet. Whereas, sonication hardly affected the fractionation, enzymatic treatment resulted in solubilisation of pellet protein and an increased lipid layer. In conclusion, processing without blanching is very effective to extract more lipids (>80%) from whole larvae in the form of a cream layer, while blanched-enzymatic treatment allows the extraction of lipids in a clear lipid layer (>40%). In both cases, around 50% of protein was recovered in the residue and the other 50% mainly in the pellet after centrifugation.

    Sedimentation and transport of different soil colloids : Effects of goethite and humic acid
    Chen, Yali ; Ma, Jie ; Wu, Xiaojuan ; Weng, Liping ; Li, Yongtao - \ 2020
    Water 12 (2020)4. - ISSN 2073-4441
    Goethite - Humic acid - Sedimentation - Soil colloid - Transport

    Soil colloids significantly facilitate the transport of contaminants; however, little is known about the effects of highly reactive iron oxide and the most representative organic matter on the transport of soil colloids with different physicochemical properties. This study investigated the effects of goethite (GT) and humic acid (HA) on the sedimentation and transport of soil colloids using settling and column experiments. The stability of soil colloids was found to be related to their properties and decreased in the following order: black soil colloids (BSc) > yellow soil colloids (YSc) > fluvo-aquic soil colloids (FSc). Organic matter increased the stability of BSc, and ionic strength (Ca2+) promoted the deposition of FSc. Colloids in individual and GT colloids (GTc) coexistence systems tended to stabilize at high pH and showed a pH-dependence whereby the stability decreased with decreasing pH. The interaction of GTc and kaolinite led to a dramatic sedimentation of YSc at pH 4.0. HA enhanced the stability of soil colloids, especially at pH 4.0, and obscured the pH-dependent sedimentation of soil colloids. The transport ability of soil colloids was the same as their stability. The addition of GT retarded the transport of soil colloids, which was quite obvious at pH 7.0. This retardation effect was attributed to the transformation of the surface charge of sand from negative to positive, which increased the electrical double-layer attraction. Although sand coated with GT-HA provided more favorable conditions for the transport of soil colloids in comparison to pure sand, the corresponding transport was relatively slow. This suggests that the filtration effect, heterogeneity, and increased surface roughness may still influence the transport of soil colloids.

    Spatial scale, neighbouring plants and variation in plant volatiles interactively determine the strength of host–parasitoid relationships
    Aartsma, Yavanna ; Pappagallo, Silvia ; Werf, Wopke van der; Dicke, Marcel ; Bianchi, Felix J.J.A. ; Poelman, Erik H. - \ 2020
    Oikos 129 (2020)9. - ISSN 0030-1299 - p. 1429 - 1439.
    herbivore-induced plant volatiles - host–parasitoid interactions - insect–plant interactions - plant neighbourhood

    Species-specific responses to the environment can moderate the strength of interactions between plants, herbivores and parasitoids. However, the ways in which characteristics of plants, such as genotypic variation in herbivore induced volatiles (HIPVs) that attract parasitoids, affect trophic interactions in different contexts of plant patch size and plant neighbourhood is not well understood. We conducted a factorial field experiment with white cabbage Brassica oleracea accessions that differ in the attractiveness of their HIPVs for parasitoids, in the context of different patch sizes and presence or absence of surrounding Brassica nigra plants. Parasitism rates of experimentally introduced Pieris brassicae caterpillars and the presence of naturally occurring Pieris spp. caterpillars in the plots were assessed throughout the growing season. The abundance of Pieris caterpillars was neither affected by cabbage accession nor plot size. Later in the season, when B. nigra plants had senesced, fewer caterpillars were found on cabbage plants in plots with a B. nigra border. Parasitism rates fluctuated over the season, and were not affected by plot size. However, the B. nigra border negatively affected parasitism rates on the accession that is less attractive to the parasitoid Cotesia glomerata, but not on the more attractive accession. Our results show that plant variation in HIPVs can differentially influence herbivores and parasitoids depending on characteristics of the surrounding vegetation context. These findings underscore the importance of considering the interaction between focal plant traits and neighbourhood context to reliably predict trophic cascades.

    Insects for peace
    Barragán-Fonseca, Katherine Y. ; Barragán-Fonseca, Karol B. ; Verschoor, Gerard ; Loon, Joop J.A. van; Dicke, Marcel - \ 2020
    Current Opinion in Insect Science 40 (2020). - ISSN 2214-5745 - p. 85 - 93.

    Insects such as the black soldier fly (BSF) are a nutritious feed component for livestock with high protein levels. BSF can be reared on a wide range of organic residual streams. This allows for local production within a circular agriculture, decoupling livestock production from import of expensive feed components, such as fishmeal or soymeal. Rearing of BSF can be done by smallholder farmers, thus contributing to their livelihood, economic sustainability and social status. Smallholder farmers contribute importantly to food security, which is a prerequisite for a stable society. In armed conflicts, smallholder farmers are usually the first to suffer. In countries recovering from conflict, agricultural development should focus on restoring food production by smallholder farmers, improving their socio-economic position, thereby contributing to sustainable development goals 2 (zero hunger) and 16 (peace and justice). Here, we focus on these SDGs with an example of reintegration of ex-combatants as smallholder insect producers in post-conflict Colombia.

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