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Varying degree of physiological integration among host instars and their endoparasitoid affects stress-induced mortality
Gols, Rieta ; Ros, Vera I.D. ; Ode, Paul J. ; Vyas, Dhaval ; Harvey, Jeffrey A. - \ 2019
Entomologia Experimentalis et Applicata (2019). - ISSN 0013-8703
Braconidae - Cotesia glomerata - host regulation - Hymenoptera - insect herbivores - Lepidoptera - multitrophic interactions - parasitoids - pathogens - Pieridae - Pieris brassicae
In natural populations of insect herbivores, genetic differentiation is likely to occur due to variation in host plant utilization and selection by the local community of organisms with which they interact. In parasitoids, engaging in intimate associations with their host during immature development, local variation may exist in host quality for parasitoid development. We compared the development of a gregarious endoparasitoid, Cotesia glomerata L. (Hymenoptera: Braconidae), collected in The Netherlands, in three strains and three caterpillar instars (L1–L3) of its main host, Pieris brassicae L. (Lepidoptera: Pieridae). Hosts had been collected in The Netherlands and France, and were reared in the laboratory for one generation. We also used an established Dutch laboratory strain that had not been exposed to parasitoids for at least 24 generations. Parasitoid survival to adulthood was inversely correlated with host instar at parasitism. Adult parasitoid body mass was largest when hosts were parasitized as L1 and smallest when hosts were parasitized as L3, whereas egg-to-adult development time was quickest on L3 hosts and slowest on L1 hosts. Higher survival and faster development of C. glomerata on French L2 hosts also showed that there is variation in host-instar-related suitability. Many L2 and most L3 caterpillars that were parasitized exhibited signs of pathogen infection and perished within a few days of parasitism, whereas this never happened when hosts were parasitized as L1 or in non-parasitized control caterpillars. Our results reveal that, irrespective of the host strain, L1 hosts are optimally synchronized with C. glomerata development. By contrast, the high precocious mortality of L3 larvae may be due to stress-induced regulation by the parasitoid in order to ‘force’ its developmental program into synchrony with the developing parasitoid larvae. Our results underscore a potentially important role played by pathogens in mediating herbivore–parasitoid interactions that are host-instar-dependent in their expression.
Ode aan een andere manier van jagen
Boonman-Berson, Susan - \ 2018
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.
Sensitivity analysis methodologies for analysing emergence using agent-based models
Broeke, Guus ten - \ 2017
Wageningen University. Promotor(en): Jaap Molenaar, co-promotor(en): George van Voorn; Arend Ligtenberg. - Wageningen : Wageningen University - ISBN 9789463436991 - 211
mathematics - computational mathematics - mathematical models - dynamic modeling - sensitivity analysis - adaptation - methodology - simulation - wiskunde - computerwiskunde - wiskundige modellen - dynamisch modelleren - gevoeligheidsanalyse - adaptatie - methodologie - simulatie
Many human and natural systems are highly complex, because they consist of many interacting parts. Such systems are known as complex adaptive systems (CAS). Understanding CAS is possible only by studying the interactions between constituent parts, rather than focussing only on the properties of the parts in isolation. Often, the possibilities for systematically studying these interactions in real-life systems are limited. Simulation models can then be an important tool for testing what properties may emerge, given various assumptions on the interactions in the system. Agent-based models (ABMs) are particularly useful for studying CAS, because ABMs explicitly model interactions between autonomous agents and their environment.
Currently, the utility of ABMs is limited by a lack of available methodologies for analysing their results. The main tool for analysing CAS models is sensitivity analysis. Yet, standard methods of sensitivity analysis are not well-suited to deal with the complexity of ABMs. Thus, there is a need for sensitivity analysis methodologies that are specifically developed for analysing ABMs. The objective of this thesis is to contribute such methodologies. Specifically, we propose methodologies for (1) detecting tipping points, (2) analysing the effects of agent adaptation, and (3) analysing resilience of ABMs.
Chapter 2 introduces traditional methods of sensitivity analysis. These methods are demonstrated by applying them to rank the most influential parameters of an ODE model of predator-prey interaction. Furthermore, the role of sensitivity analysis in model validation is discussed.
In Chapter 3 we investigate the use of sensitivity analysis for detecting tipping points. Whereas bifurcation analysis methods are available for detecting tipping points in ODE models, these methods are not applicable to ABMs. Therefore, we use an ODE model to verify the results from sensitivity analysis against those of bifurcation analysis. We conclude that one-factor-at-a-time sensitivity analysis (OFAT) is a helpful method for detecting tipping points. However, OFAT is a local method that considers only changes in individual parameters. It is therefore recommended to supplement OFAT with a global method to investigate interaction effects. For this purpose, we recommend all-but-one-at-a-time sensitivity analysis (ABOS) as a graphical sensitivity analysis method that takes into account parameter interactions and can help with the detection of tipping points.
In Chapter 4 we introduce a basic ABM model of agents competing in a spatial environment for a renewable resource. This basic model will be extended in the subsequent chapters, and will serve as a testing case for various sensitivity analysis methods. In Chapter 4, it is used to assess the utility of existing sensitivity analysis methods for ABMs. The results show that traditional methods of sensitivity are not sufficient to analyse the ABM, due to the presence of tipping points and other strong non-linearities in the model output. In contrast, OFAT is found to be helpful for detecting tipping points, as was suggested in Chapter 3. Based on these outcomes, OFAT is recommended as a starting point for sensitivity analysis of ABMs, preferably supplemented by a global method to investigate interaction effects.
In Chapter 5 we extend the ABM of Chapter 4 by adding agent adaptation in the form of a mechanism of natural selection. On short time-scales, the model behaviour appears to be similar to the non-adaptive model version. On longer time-scales, the agent adaptation causes the state of the model to gradually change as agents continue to adapt to their surroundings. We propose a sensitivity analysis method to measure the effects of this adaptation. This method is based on a quantification of the difference between probability density functions of model version with and without adaptation. Using this method, we show that this adaptation increases the resilience of the system by giving it the flexibility needed to respond to pressures.
In Chapter 6 we further extend the test-case by giving agents the option to harvest either cooperatively or individually. Cooperation increases the potential yields, but introduces the risk of defection of the interaction partner. It is shown that ecological factors, which are usually not considered in models on cooperation, strongly affect the level of cooperation in the system. For example, low levels of cooperation lead to a decreased population size, and causes the formation of small groups of agents with a higher level of cooperation. As a result, cooperation persists even without any mechanisms to promote it. Nevertheless, the inclusion of such mechanisms in the form of indirect reciprocity does further increase the level of cooperation. Furthermore, we show that the resulting high levels of cooperation, depending on the circumstances, can increase the resilience of the agent population against shocks.
To conclude, in this thesis several methodologies have been proposed to help with ABM analysis. Specifically, OFAT and ABOS are recommended for detecting tipping points in ABMs, and in Chapter 5 a protocol is introduced for quantifying the effects of adaptation. By suggesting these methodologies, this thesis aims to contribute to the utility of ABMs, especially for studying CAS.
Differential induction of plant chemical defenses by parasitized and unparasitized herbivores : Consequences for reciprocal, multitrophic interactions
Ode, Paul J. ; Harvey, J.A. ; Reichelt, Michael ; Gershenzon, Jonathan ; Gols, Rieta - \ 2016
Oikos 125 (2016)10. - ISSN 0030-1299 - p. 1398 - 1407.
Insect parasitoids can play ecologically important roles in virtually all terrestrial plant-insect herbivore interactions, yet whether parasitoids alter the defensive traits that underlie interactions between plants and their herbivores remains a largely unexplored question. Here, we examined the reciprocal trophic interactions among populations of the wild cabbage Brassica oleracea that vary greatly in their production of defensive secondary compounds - glucosinolates (GSs), a generalist herbivore, Trichoplusia ni, and its polyembryonic parasitoid Copidosoma floridanum. In a greenhouse environment, plants were exposed to either healthy (unparasitized), parasitized, or no herbivores. Feeding damage by herbivores induced higher levels of the indole GSs, glucobrassicin and neoglucobrassicin, but not any of the other measured GSs. Herbivores parasitized by C. floridanum induced cabbage plants to produce 1.5 times more indole GSs than levels induced by healthy T. ni and five times more than uninduced plants. As a gregarious endoparasitoid, C. floridanum causes its host T. ni to feed more than unparasitized herbivores resulting in increased induction of indole GSs. In turn, herbivore fitness parameters (including differential effects on male and female contributions to lifetime fecundity in the herbivore) were negatively correlated with the aliphatic GSs, sinigrin and gluconapin, whereas parasitoid fitness parameters were negatively correlated with the indole GSs, glucobrassicin and neoglucobrassicin. That herbivores and their parasitoids appear to be affected by different sets of GSs was unexpected given the intimate developmental associations between host and parasitoid. This study is the first to demonstrate that parasitoids, through increasing feeding by their herbivorous hosts, can induce higher levels of non-volatile plant chemical defenses. While parasitoids are widely recognized to be ubiquitous in most terrestrial insect herbivore communities, their role in influencing plant-insect herbivore relationships is still vastly underappreciated.
Short-term seasonal habitat facilitation mediated by an insect herbivore
Harvey, Jeffrey A. ; Ode, Paul J. ; Malcicka, Miriama ; Gols, Rieta - \ 2016
Basic and Applied Ecology 17 (2016)5. - ISSN 1439-1791 - p. 447 - 454.
Clubiona phragmitis - Community - Earwig - Ecological interactions - Forficula auricularia - Porcellio scaber - Spider - Woodlice
In nature some organisms may facilitate others by creating shelter or other niches that they use for variable periods. We describe a natural multitrophic-species complex in the Netherlands involving a plant, the common hogweed (Heracleum sphondylium) a specialist chewing herbivore, the parsnip webworm (Depressaria pastinacella) and various arthropods associated with them. Larvae of D. pastinacella feed on H. sphondylium seeds and, after they have finished feeding, chew holes in the hollow stems where they pupate. In some areas of the country almost 50% of plants are attacked by webworms. The holes are used by other arthropods to gain access to the stems including herbivores, omnivores, predators and decomposers. The duration of plant occupancy varies between 3 and 4 months, until the plants die. Plants without moth-produced holes were always free of other arthropods, whereas plants with holes, in addition to pupae (and/or mummified-parasitized webworm larvae), often contained many woodlice, earwigs and/or spiders. Earwigs and woodlice perform important ecological functions as predators (in orchards) and decomposers respectively. Our results show that the simple biological activity of one herbivore species can have at least short-term effects on the local arthropod community. In der Natur können manche Organismen andere begünstigen, indem sie Refugien oder andere Nischen erschaffen, die sie für unterschiedliche Zeiträume nutzen. Wir beschreiben einen natürlichen multitrophischen Artenkomplex in den Niederlanden, der den Wiesen-Bärenklau (Heracleum sphondylium), die Pastinakmotte (Depressaria pastinacella) und verschiedene mit ihnen assoziierte Arthropoden umfasst. Die Larven der Pastinakmotte fressen an Bärenklausamen und beißen später Löcher in die hohlen Stengel, um sich darin zu verpuppen. Die Löcher werden von anderen Arthropoden genutzt, um Zugang ins Stengelinnere zu erhalten. Die Pflanze wird für etwa drei bis vier Monate besiedelt bis sie abstirbt. Pflanzen ohne Mottenlöcher wurden niemals von anderen Arthropoden besiedelt, während Stengel mit Löchern zusätzlich zu den Mottenpuppen bzw. parasitierten Larvenmumien häufig viele Asseln, Ohrwürmer und/oder Spinnen enthielten. Ohrwürmer und Asseln erfüllen wichtige ökologische Funktionen als Räuber in Obstplantagen bzw. als Zersetzer. Unsere Ergebnisse zeigen, dass die einfache biologische Aktivität einer Herbivorenart zumindest kurzfristige Auswirkungen auf die lokale Arthropodengemeinschaft haben kann.
Data from:Differential induction of plant chemical defenses by parasitized and unparasitized herbivores: consequences for reciprocal, multitrophic interactions
Ode, Paul J. ; Harvey, J.A. ; Reichelt, Michael ; Gershenzon, Jonathan ; Gols, R. - \ 2015
multitrophic interactions - parasitoids - plant chemical defenses - Brassica oleracea - Trichoplusia ni - Copidosoma floridanum
Insect parasitoids can play ecologically important roles in virtually all terrestrial plant–insect herbivore interactions, yet whether parasitoids alter the defensive traits that underlie interactions between plants and their herbivores remains a largely unexplored question. Here, we examined the reciprocal trophic interactions among populations of the wild cabbage Brassica oleracea that vary greatly in their production of defensive secondary compounds – glucosinolates (GSs), a generalist herbivore, Trichoplusia ni, and its polyembryonic parasitoid Copidosoma floridanum. In a greenhouse environment, plants were exposed to either healthy (unparasitized), parasitized, or no herbivores. Feeding damage by herbivores induced higher levels of the indole GSs, glucobrassicin and neoglucobrassicin, but not any of the other measured GSs. Herbivores parasitized by C. floridanum induced cabbage plants to produce 1.5 times more indole GSs than levels induced by healthy T. ni and five times more than uninduced plants. As a gregarious endoparasitoid, C. floridanum causes its host T. ni to feed more than unparasitized herbivores resulting in increased induction of indole GSs. In turn, herbivore fitness parameters (including differential effects on male and female contributions to lifetime fecundity in the herbivore) were negatively correlated with the aliphatic GSs, sinigrin and gluconapin, whereas parasitoid fitness parameters were negatively correlated with the indole GSs, glucobrassicin and neoglucobrassicin. That herbivores and their parasitoids appear to be affected by different sets of GSs was unexpected given the intimate developmental associations between host and parasitoid. This study is the first to demonstrate that parasitoids, through increasing feeding by their herbivorous hosts, can induce higher levels of non-volatile plant chemical defenses. While parasitoids are widely recognized to be ubiquitous in most terrestrial insect herbivore communities, their role in influencing plant–insect herbivore relationships is still vastly underappreciated.
Shape and stability in liquid threads and jets : a link to droplet formation
Heugten, W.G.N. van - \ 2015
Wageningen University. Promotor(en): Cees van Rijn. - Wageningen : Wageningen University - ISBN 9789462575707 - 172
droplets - controlled droplet application - threads - viscosity - stability - fluid mechanics - druppels - draden - viscositeit - stabiliteit - vloeistofmechanica
This thesis explores relevant fluid dynamic processes for the formation of uniformly sized droplets in microfluidic systems. Growing droplets made from a bulk source have often liquid threads or jets in between to supply liquid to the droplet. Liquid threads and jets are however known to be instable and finding parameters determining their instability/stability will possibly promote a more controlled formation of uniformly sized droplets. Different droplet formation processes in microfluidic devices are explained, such as cross-flow, co-flow and flow focussing.
Dimensionless numbers (introduced in chapter 1) represent the ratio of relevant forces or pressures acting on the fluids and/or their interfaces. These forces and pressures originate from their related fluid dynamic parameters, such as viscosity, interfacial tension, mass density and velocity of the fluid within a specific fluidic confinement with a certain length scale. We show that the dimensionless Reynolds, Weber and Capillary numbers can be associated with the stability of liquid threads and/or jets and provide insight in droplet formation processes.
The phenomenon of spontaneous droplet formation at low flow rates of an inner fluid confined in a microfluidic channel is studied in chapter 2. A short overview of known processes of spontaneous droplet formation with micro-engineered microfluidic devices is presented. We have studied the process of auto breakup with rectangular and round glass capillaries, the latter provided with micro-corrugations and uniform sized droplets were obtained, but only if the outer fluid is able to enter the capillary during droplet formation.
The process of auto breakup is described by a new analytical model described in chapter 3. The model states that the instability of a liquid thread is induced by the decrease of a local liquid thread pressure inside the capillary near the growing droplet. Predicted droplet sizes have been experimentally verified accurately, and also the predicted breakup length inside a micro-corrugated capillary has been verified. The model states that viscous flow stabilises the liquid thread and that auto breakup happens as long as the capillary number is below a critical capillary number of 0.0625. Above 0.0625 droplets grow infinitely large. Auto breakup is however already hampered at Capillary numbers above 0.03, because between 0.03 and 0.0625 no well controlled droplet sizes could be obtained by auto breakup. This is explained by the observed formation of a partially collapsed inner liquid thread that remains open and supplies the growing droplet with inner fluid.
In chapter 4 the formation and stability of a liquid thread in free surface flow feeding a large growing droplet is demonstrated and discussed. The shape of the liquid thread is positively tapering (towards the droplet) and can be described accurately by a Navier-Stokes based ordinary differential equation (ODE) assuming steady state, axisymmetry and an averaged fluid velocity over the cross section of the liquid thread. The axial shape of a viscous liquid thread is concave and its radial dimension has initially a cubic dependence with respect to the axial dimension. A driving force to stabilise the liquid thread was identified, which is a pressure gradient Q = Q0/L – Q1. Q0 is the pressure drop over thread length L, and Q1 is interfacial based dissipation of energy of the outer fluid. The maximum length of the liquid thread is predicted to be reached when Q goes towards 0 as the ratio Q0/Q1.
Shape and stability of emanating liquid jets, which appear after impact of falling droplets from a deep liquid, is presented in chapter 5. During rise and fall of the jet due to gravity, the jet is additionally decelerated towards the liquid surface by a tensile retraction force from the surface tension force exerted on the jet surface by the liquid bath. The retracting force generates an inertial deceleration pressure inside the jet that is balanced by the local Laplace pressure, herewith defining its local curvature and therefore also the shape of the complete jet. A deceleration based Young-Laplace equation is introduced and the predicted shape is experimentally verified for different fluids. Furthermore, the size of droplets forming on the tip of the jet can also be explained by the found pressure balance between the local Laplace pressure and the inertial deceleration of the jet (including the forming droplet).
In general we found that the stability of a liquid thread or jet seems correlated with an applied pressure difference that is distributed between the begin and end of the thread or jet. Studying auto breakup (chapters 2 and 3) of a confined liquid thread it was found that only when the applied pressure is high enough the liquid thread is stable and infinitely large droplets are formed. For the free surface flow liquid thread (chapter 4) it was found that breakup happens when the applied pressure gradient over the length of the thread goes to zero. For the emanating jet (chapter 5) an inertial pressure difference between the base and tip of the jet comes into existence that opposes the squeezing Laplace pressure that wants to break up the liquid jet. Furthermore we found that the last stages of droplet breakup from a liquid thread or jet appeared to follow universal pinch-off, and also that micro-thread formation is observed between droplet and liquid thread or jet.
Recordaantal meldingen van hooikoortsplant Ambrosia
Vliet, A.J.H. van; Bron, W.A. ; Lammers, Wiebe ; Ode, B. ; Wissen, H. van; Martens, M. ; Weger, L.A. de - \ 2014
Wageningen : Allergieradar.nl
Analyse trend en hotspots Alsemambrosia
Beringen, R. ; Odé, B. ; Vliet, A.J.H. van - \ 2014
ambrosia - ambrosia artemisiifolia - invasieve exoten - verspreiding van planten - kenmerken - onkruiden - analyse - detectie - populaties - nederland - invasive alien species - plant dispersal - traits - weeds - analysis - detection - populations - netherlands
Alsemambrosia is de meest voorkomende Ambrosiasoort in Nederland. Na bundeling van de gegevens van de belangrijkste bronnen van waarnemingen door FloravanNederland.nl, De Natuurkalender Wageningen UR, NDFF en Waarneming.nl is een analyse gedaan naar verspreiding en trend van Alsemambrosia in de periode 1975 t/m 2013. Tevens is op basis van de beschikbare gegevens een analyse gedaan naar de omvang van populaties in de periode 2000-2013.
A New Modified Histogram Matching Normalization for Time Series Microarray Analysis
Astola, L. ; Molenaar, J. - \ 2014
Microarrays 3 (2014)3. - ISSN 2076-3905 - p. 203 - 211.
Microarray data is often utilized in inferring regulatory networks. Quantile normalization (QN) is a popular method to reduce array-to-array variation. We show that in the context of time series measurements QN may not be the best choice for this task, especially not if the inference is based on continuous time ODE model. We propose an alternative normalization method that is better suited for network inference from time series data.
Observed climate-induced changes in plant phenology in the Netherlands
Vliet, A.J.H. van; Bron, W.A. ; Mulder, S. ; Slikke, W. van der; Odé, B. - \ 2014
Regional Environmental Change 14 (2014)3. - ISSN 1436-3798 - p. 997 - 1008.
urbanization - temperature - europe - trends - time
We determined whether climate change in the Netherlands has caused phenological changes since 1868. We analysed over 150,000 plant phenological observations of 320 plant species, obtained by four volunteer networks and one series collected by Mr. Braaksma. With the network data, we compared the timing of life cycle events in three different periods: 1894–1932 (Period 1), 1940–1968 (Period 2) and 2001–2010 (Period 3). For the Braaksma series, we compared the periods 1953–1968 (Period A) with 1969–1992 (Period B). We conclude that until the beginning of the 1990s, there have been no significant changes in the timing of life cycle events. The timing of life cycle events in Period 3 showed an average advance of flowering, leaf unfolding and fruit ripening of 14 days compared with Period 1 and 13 days compared with Period 2. Some species have advanced up to over 35 days. Autumn events occurred up to an average of 7 days later in Period 3 compared to earlier periods. This study shows that, based on network data, changes in climate explain on average 66 % of the variation in timing of phenological events from year to year. For the Braaksma data, this is 38 %. The expected future changes in climate will undoubtedly result in a further lengthening of the growing season. We believe that phenological networks, supported by thousands of volunteers, are needed to quantify, analyse, predict and communicate these phenological changes so various sectors in society can adapt to these changes and prevent significant socio-economic impacts.
Species richness declines and biotic homogenisation have slowed down for NW-European pollinators and plants.
Carvalheiro, L.G. ; Kunin, W.E. ; Keil, P. ; Aguirre-Gutiérrez, J. ; Ellis, W.N. ; Fox, R. ; Groom, Q. ; Hennekens, S. ; Landuyt, W. Van; Maes, D. ; Meutter, F. Van de; Michez, D. ; Rasmont, P. ; Ode, B. ; Potts, S.G. ; Reemer, M. ; Roberts, S.P.M. ; Schaminée, J. ; Wallis de Vries, M.F. ; Biesmeijer, J.C. - \ 2013
Ecology Letters 16 (2013)7. - ISSN 1461-023X - p. 870 - 878.
agri-environment schemes - global biodiversity - british butterflies - diversity - abundance - britain - scale - netherlands - indicators - similarity
Concern about biodiversity loss has led to increased public investment in conservation. Whereas there is a widespread perception that such initiatives have been unsuccessful, there are few quantitative tests of this perception. Here, we evaluate whether rates of biodiversity change have altered in recent decades in three European countries (Great Britain, Netherlands and Belgium) for plants and flower visiting insects. We compared four 20-year periods, comparing periods of rapid land-use intensification and natural habitat loss (1930–1990) with a period of increased conservation investment (post-1990). We found that extensive species richness loss and biotic homogenisation occurred before 1990, whereas these negative trends became substantially less accentuated during recent decades, being partially reversed for certain taxa (e.g. bees in Great Britain and Netherlands). These results highlight the potential to maintain or even restore current species assemblages (which despite past extinctions are still of great conservation value), at least in regions where large-scale land-use intensification and natural habitat loss has ceased.
Kasteelt (innovaties in de glastuinbouw, met Tycho Vermeulen en Leo Ammerlaan)
Muusze, B. ; Vermeulen, T. ; Ammerlaan, L. - \ 2013
glastuinbouw - energiebesparing - belichting - innovaties - algenteelt - warmte - duurzaamheid (sustainability) - biobased economy - greenhouse horticulture - energy saving - illumination - innovations - algae culture - heat - sustainability
De Stichting Duurzame Stad organiseert in Zoetermeer en Gouda een ontwerpwedstrijd ‘duurzame stad van de toekomst’ voor leerlingen tussen de 14 en 18 jaar. Drie middelbare scholen uit Zoetermeer en drie uit Gouda doen aan mee aan de wedstrijd. De leerlingen kunnen als hoofdprijs zonnepanelen voor op hun school winnen. Ter inspiratie voor de wedstrijd bekijken leerlingen korte filmpjes over hoe verschillende sectoren in de maatschappij werken aan verduurzaming, om vervolgens zelf aan de slag te gaan. Duurzame Voedselvoorziening is één van de oDe Stichting Duurzame Stad organiseert in Zoetermeer en Gouda een ontwerpwedstrijd ‘duurzame stad van de toekomst’ voor leerlingen tussen de 14 en 18 jaar. Drie middelbare scholen uit Zoetermeer en drie uit Gouda doen aan mee aan de wedstrijd. De leerlingen kunnen als hoofdprijs zonnepanelen voor op hun school winnen. Ter inspiratie voor de wedstrijd bekijken leerlingen korte filmpjes over hoe verschillende sectoren in de maatschappij werken aan verduurzaming, om vervolgens zelf aan de slag te gaan. Duurzame Voedselvoorziening is één van de onderwerpen. In de voedselvoorziening speelt de glastuinbouw in Nederland een belangrijke rol. De Stichting Duurzame Stad heeft daarom samen met de Omgevingsdienst Midden-Holland, de gemeente Zoetermeer en Wageningen UR Glastuinbouw een inspiratiefilmpje gemaakt. Het filmpje toont de leerlingen interessante ontwikkelingen die op dit moment plaatsvinden in kassen. Vooral de energie-aspecten van de glastuinbouw komen aan bod: . de opkomst van het ledlicht . opwekken van warmte en energie uit kassen . algenteelt en bioplastics . het verbinden van de tuinbouw met de stad Voor het laatste onderwerp zijn opnames gemaakt bij potplantenkwekerij Ammerlaan The Green Innovator in Pijnacker-Nootdorp. Finales van de ontwerpwedstrijd zijn in Zoetermeer op 24 april en in Gouda op 30 mei 2013.
OPINIE: Een wilde orchidee is inderdaad een mooie bloem
Meijrink, M. ; Odé, B. - \ 2011
Wageningen : Nature Today
Metabolic Pathway Inference from Time Series Data: A Non Iterative Approach
Astola, L.J. ; Groenenboom, M.A.C. ; Gomez Roldan, M.V. ; Eeuwijk, F.A. van; Hall, R.D. ; Bovy, A.G. ; Molenaar, J. - \ 2011
In: Pattern Recognition in Bioinformatics : 6th IAPR International Conference, PRIB 2011, Delft, The Netherlands, 2-4 November 2011 / Loog, M., Wessels, L., Berlin [etc.] : Springer (Lecture notes in computer science 7036) - ISBN 9783642248542 - p. 97 - 108.
In this article, we present a very fast and easy to implement method for reconstruction of metabolic pathways based on time series data. To model the metabolic reactions, we use the well-established setting of ordinary differential equations. In the present article we consider a network leading to the accumulation of quercetin-glycosides in tomato (Solanum lycopersicum). Quercetin belongs to a group of plant secondary metabolites, generally referred to as flavonoids, which are extensively being studied for their variety of important functions in plants as well as for their potentially health-promoting effects on human. We use time series measurements of metabolite concentrations of quercetin derivatives. In the present setting, the observed concentrations are the variables and the reaction rates are the unknown parameters. A standard method is to solve the parameters by reverse engineering, where the ordinary differential equations (ODE) are solved repeatedly, resulting in impractical computation times. We use an alternative method that estimates the parameters by least squares minimization, and which is, in the order of hundred times faster than the iterative method. Our reconstruction method can incorporate an arbitrary a priori known network structure as well as positivity constraints on the reaction rates. In this way we can avoid over-fitting, which is another often encountered problem in network reconstruction, and thus obtain better estimates for the parameters. We test the presented method by reconstructing artificial networks and compare it with the more conventional method in terms of residuals between the observed and fitted concentrations, computing times and the proportion of correctly identified edges in the network. Finally we exploit this fast method to statistically infer the kinetic constants in the flavonoid pathway. We remark that the method as such is not limited to metabolic network reconstructions, but can be used with any type of time-series data that is modeled in terms of linear ODE’s.
|Ode aan Prof. A.M. Sprenger : Interview met o.a. Marc Ravesloot
Ravesloot, Marc - \ 2011
|Mooie reisverhalen uit voedingsland
Dagevos, H. - \ 2011
Voeding Nu 13 (2011)5. - ISSN 1389-7608 - p. 29 - 30.
voedselconsumptie - voedselproductie - voedingsmiddelen - eten - maaltijden - food consumption - food production - foods - eating - meals
In zijn eigen werk heeft de auteur het herhaaldelijk over de grote paradox in de wereld van voedsel: terwijl we op ongekende wijze omringd worden door een keur aan voedselproducten zijn we tegelijkertijd nog nooit zo vervreemd geraakt van ons eten. Het is de fascinatie voor deze paradox die Volkskrant-journalist Mac van Dinther heeft aangezet om een reis door voedingsland te maken om op zoek te gaan naar verhalen over wat er op ons bord ligt. Van Dinthers odyssee is een ode aan ons eten geworden.
Alsemambrosia pas laatste jaren in de lift
Odé, B. ; Slikke, W. van der; Vliet, A.J.H. van - \ 2011
Wageningen : Nature Today
Help hooikoortsplant Ambrosia te bestrijden
Vliet, A.J.H. van; Odé, B. - \ 2011
Wageningen : Nature Today