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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    Leidraad Beheersing Eikenprocessierups : Update 2019
    Spijker, J.H. ; Hellingman, S. ; Hellingman, Guus ; Hofhuis, Hidde ; Jans, H. ; Kuppen, Henry ; Vliet, A.J.H. van - \ 2019
    Wageningen : Kenniscentrum Eikenprocessierups - 64 p.
    Deze Leidraad beheersing eikenprocessierups is een complete vernieuwing van de voorheen door de NVWAin samenwerking met Alterra (Wageningen University & Research) en Vlinderstichting uitgegeven Leidraadbeheersing eikenprocessierups (oorspronkelijk uitgegeven in 2005, 1e update 2008, 2e update 2013)(Fransen 2013).Het ministerie van LNV heeft het Kenniscentrum Eikenprocessierups onder leiding van Wageningen University& Research opdracht gegeven om de Leidraad een voorlopige update te geven zodat boomeigenaren en groenbeheerders op korte termijn toegang krijgen tot de laatste kennis over de eikenprocessierups en daarmee zo optimaal mogelijk de beheersing van de eikenprocessierups kunnen organiseren. De versie 2019 zet zo goed mogelijk de huidige inzichten ten aanzien van de beheersing van de eikenprocessierups op een rij. Voor deze leidraad is gebruik gemaakt van per 1 augustus 2019 beschikbare literatuur en expert judgement. Gelet op de korte doorlooptijd was er geen gelegenheid voor het doen van aanvullend onderzoek en uitgebreide praktijk consultaties.
    Integrating priorities of disadvantaged parents and professionals for community family health
    Wink, G. ; Fransen, G.A.J. ; Huisman, M.J. ; Boersma, S.N. ; Assendelft, Willem J.J. ; Wagemakers, A. ; Velden, J. van der; Muijsenbergh, M.E.T.C. van den - \ 2019
    The development of a monitoring instrument to measure the strength of health promoting systems
    Fransen, G. ; Wagemakers, Annemarie ; Molleman, Gerard - \ 2019
    Integrating priorities of disadvantaged parents and professionals for community family health
    Wink, G. ; Fransen, G.A.J. ; Huisman, M.J. ; Boersma, S.N. ; Assendelft, W.J.J. ; Wagemakers, M.A.E. ; Velden, J. van der; Muijsenbergh, M.E.T.C. van den - \ 2019
    European Journal of Public Health 29 (2019)Supplement_4. - ISSN 1101-1262 - p. 374 - 375.
    Background
    Health inequalities persist, and policymakers, researchers and practitioners seek for effective ways to positively impact the health of disadvantaged people. Researchers point to a multi-component program with an integral design including various perspectives and involving different stakeholders. Few studies address the perspectives on health of disadvantaged people themselves. This study describes what parents in a socially disadvantaged situation and professionals working in that community perceived as 1) priority aspects to improve family health 2) barriers and facilitators for health behaviour changes 3) important health program activities.

    Methods
    Design: Community-based participatory action research. 10 parents participated in 6 panel meetings. 46 professionals received 4 panel meetings summaries. 18 parents and 25 professionals responded to questions in (panel) meetings and consultation by phone and e-mail.
    Results
    (preliminary) 1) Parents’ top priorities for improving health were: less stress related to finances and communication with related organizations, followed by a safe place for kids to meet. Of the program financers’ aims (reducing tobacco, alcohol use and overweight) reducing overweight got relatively most support of parents. 2) Parents perceived their family financial situation as barrier to behaviours reducing stress and overweight. 3) Program activities related to reducing stress got more support from parents and professionals than activities related to reducing overweight.

    Conclusions
    Insight in the perspectives of disadvantaged parents and professionals resulted in a program plan supported by them, aiming to reduce stress and overweight. Most participating parents and professionals committed themselves to invest time in program activities execution.
    Key messages
    Disadvantaged parents perceived reducing stress related to finances as top priority to improve family health. They perceived family finances as barrier to behaviours reducing stress and overweight.
    Community-based participatory action research with disadvantaged parents and professionals can result in an integrated family health program plan with stakeholder support.
    The development of a monitoring instrument to measure the strength of health promoting systems
    Fransen, G. ; Wagemakers, A. ; Molleman, G. - \ 2019
    European Journal of Public Health 29 (2019)Supplement_4. - ISSN 1101-1262 - p. 224 - 224.
    Background: In the region of the Municipality Health Services GelderlandSouth, each municipality has its own health broker. He or sheadvises the local policy makers, signals/pleads for addressinghealth problems, and facilitates effective approaches. By doingthis health brokers try to strengthen the local health promotingsystem. To show the results of health brokers and to monitorchanges of the local health promoting system, the MHS needs amonitoring instrument. The aim of this study was to developthis instrument and to test it in practice. Methods: Participatory action (qualitative) research is used to develop anonline questionnaire. Structured group processes with the healthbrokers has led to the identification and definition of eightvariables, reflecting the health promoting system: collaboration,support, integrated approach, visibility of results, health monitordata assessment, consistency, reach of the target population andsustainability. A literature study identified appropriate instruments. The online questionnaire is expanded to test the reliability,to evaluate the usability and to gain insight into the strength ofthe health promoting system in 16 municipalities. Results: The questionaire is based on validated questionaires like theCoordinated Action Checklist, and contains 28 items.Sumscores per variable ranged from 0 (weak) to 100(strong). Health brokers and their partners (N = 147, 4-9per municipality) filled out the questionnaire. Support andcollaboration had the highest mean scores (70,5 resp. 69,8),and visibility of results and sustainability the lowest (61,3 resp.59,4). Differences between municipalities were identified andcan be used to know which variables can be improved. Thetest-retest reliability (mean r = 0,713) and the Crohnbachsalphas (all > 0,70) were reasonable good. Conclusions: The questionnaire can help to provide useful insights in the strengths and weaknesses of the local health promoting system.
    Key messages: Eight variables reflect the health promoting system: collaboration, support, integrated approach, visibility ofresults, health monitor data assessment, consistency, reach and sustainability. The questionnaire can help to provide useful insights in the strengths and weaknesses of the local health promoting system.
    Oxidative stress and immune aberrancies in attention-deficit/hyperactivity disorder (ADHD): a case–control comparison
    Verlaet, Annelies A.J. ; Breynaert, Annelies ; Ceulemans, Berten ; Bruyne, Tess De; Fransen, Erik ; Pieters, Luc ; Savelkoul, Huub F.J. ; Hermans, Nina - \ 2019
    European Child & Adolescent Psychiatry 28 (2019)5. - ISSN 1018-8827 - p. 719 - 729.
    ADHD - Antioxidants - Diet - Immunity - Oxidative stress

    The objective of this study is to compare oxidative stress and immune biomarkers between attention-deficit/hyperactivity disorder (ADHD) patients and controls without ADHD. A case–control comparison between 57 paediatric (6–12 years) untreated ADHD patients from the Antwerp University Hospital and 69 controls without ADHD from random schools in Flanders, Belgium, was conducted. Erythrocyte glutathione (GSH) and plasma lipid-soluble antioxidants (retinol, α-tocopherol, γ-tocopherol, retinyl palmitate, β-carotene, and co-enzyme Q10) were determined by HPLC with electrochemical detection, plasma malondialdehyde (MDA) by HPLC with fluorescence detection, plasma cytokines (interleukin (IL)-1β, IL-5, IL-6, IL-8, IL-10, tumour necrosis factor (TNF) and interferon (INF)-γ) and immunoglobulins (IgE, IgG and IgM) by flow cytometry and urinary 8-hydroxy-2′deoxyguanosine (8-OHdG) levels by ELISA assay. Dietary habits were determined by a food frequency questionnaire. Plasma MDA levels were on average 0.031 µM higher in patients than in controls (p < 0.05), and a trend for higher urinary 8-OHdG was observed. Erythrocyte GSH and plasma retinyl palmitate levels, as well as IgG and IgE levels, were higher in patients than in controls as well (on average 93.707 µg/ml, 0.006 µg/ml, 301.555 µg/ml and 125.004 µg/ml, resp., p < 0.05). Finally, a trend for lower plasma IL-5 levels was observed. After Bonferroni correction for multiple testing, the difference in GSH levels remained statistically significant (nominally significant for retinyl palmitate), while significance was lost for MDA, IgG and IgE levels. Dietary habits do not appear to cause the observed differences. These results point at the potential involvement of slight oxidative stress and immune disturbances in ADHD.

    Ondervoeding bij ouderen staat nog te weinig op het netvlies
    Groot, C.P.G.M. de - \ 2019
    Are the G20 economies making enough progress to meet their NDC targets?
    Elzen, Michel den; Kuramochi, Takeshi ; Höhne, Niklas ; Cantzler, Jasmin ; Esmeijer, Kendall ; Fekete, Hanna ; Fransen, Taryn ; Keramidas, Kimon ; Roelfsema, Mark ; Sha, Fu ; Soest, Heleen van; Vandyck, Toon - \ 2019
    Energy Policy 126 (2019). - ISSN 0301-4215 - p. 238 - 250.
    China - G20 economies - National climate and energy policies - NDCs - Paris Agreement

    Under the Paris Agreement, countries committed to a variety of climate actions, including post-2020 greenhouse gas (GHG) emissions reduction targets. This study compares projected GHG emissions in the G20 economies under current climate policies to those under the GHG targets outlined in the nationally determined contributions (NDCs). It is based on an assessment of official governmental estimates and independent national and global studies. The study concludes that six G20 members (China, India, Indonesia, Japan, Russia and Turkey) are projected to meet their unconditional NDC targets with current policies. Eight members (Argentina, Australia, Canada, the European Union, Republic of Korea, South Africa and the United States) require further action to achieve their targets. Insufficient information is available for Saudi Arabia, and emission projections for Brazil and Mexico are subject to considerable uncertainty. The study also presents high-level decarbonisation indicators to better understand the current progress towards meeting the NDCs – Saudi Arabia and South Africa were found to continue increasing both emission intensity per unit GDP and emissions per capita under current policies by 2030 from 2015 levels.

    Groen in het gedrang
    Marcelis, L.F.M. - \ 2018
    Voluntary Sustainability Standards, Trade and Sustainable Development : 3rd Flagship Report of the United Nations Forum on Sustainability Standards (UNFSS)
    Fernandez de Cordoba, Santiago ; Onguglo, Bonapas ; Hoekman, Bernard ; Schleifer, Philip ; Fiorini, Matteo ; Fransen, Luc ; Gjaltema, J.G. - \ 2018
    - 74 p.
    Aged mice display altered numbers and phenotype of basophils, and bone marrow-derived basophil activation, with a limited role for aging-associated microbiota
    Beek, Adriaan A. Van; Fransen, Floris ; Meijer, Ben ; Vos, Paul de; Knol, Edward F. ; Savelkoul, Huub F.J. - \ 2018
    Immunity and Ageing 15 (2018)1. - ISSN 1742-4933
    Aging - Basophils - Bone marrow - Immunity - Microbiota - Spleen

    Background: The influence of age on basophils is poorly understood, as well as the effect of aging-associated microbiota on basophils. Therefore, we studied the influence of aging and aging-associated microbiota on basophil frequency and phenotype, and differentiation from basophil precursors. Results: Basophils became more abundant in bone marrow (BM) and spleens of 19-month-old mice compared with 4-month-old mice. Aged basophils tended to express less CD200R3 and more CD123, both in BM and spleen. Differences in microbiota composition with aging were confirmed by 16S sequencing. Microbiota transfers from young and old mice to germ-free recipients revealed that CD11b tended to be lowered on splenic basophils by aging-associated microbiota. Furthermore, abundance of Alistipes, Oscillibacter, Bacteroidetes RC9 gut group, and S24-7 family positively correlated and CD123 expression, whereas Akkermansia abundance negatively correlated with basophils numbers. Subsequently, we purified FcϵRIα+CD11c-CD117- BM-derived basophils and found that those from aged mice expressed lower levels of CD11b upon stimulation. Higher frequencies of IL-4+ basophils were generated from basophil precursors of aged mice, which could be reproduced in basophils derived from germ-free recipients of aging-associated microbiota. Conclusions: Collectively, these results show the influence of aging on basophils. Furthermore, this study shows that aging-associated microbiota altered activation of BM-derived basophils in a similar fashion as observed in BM-derived basophils from aged mice.

    Sex differences in lipid metabolism are affected by presence of the gut microbiota
    Baars, Annemarie ; Oosting, Annemarie ; Lohuis, Mirjam ; Koehorst, Martijn ; Aidy, Sahar El; Hugenholtz, Floor ; Smidt, Hauke ; Mischke, Mona ; Boekschoten, Mark V. ; Verkade, Henkjan J. ; Garssen, Johan ; Beek, Eline M. van der; Knol, Jan ; Vos, Paul de; Bergenhenegouwen, Jeroen van; Fransen, Floris - \ 2018
    Scientific Reports 8 (2018)1. - ISSN 2045-2322

    Physiological processes are differentially regulated between men and women. Sex and gut microbiota have each been demonstrated to regulate host metabolism, but it is unclear whether both factors are interdependent. Here, we determined to what extent sex-specific differences in lipid metabolism are modulated via the gut microbiota. While male and female Conv mice showed predominantly differential expression in gene sets related to lipid metabolism, GF mice showed differences in gene sets linked to gut health and inflammatory responses. This suggests that presence of the gut microbiota is important in sex-specific regulation of lipid metabolism. Further, we explored the role of bile acids as mediators in the cross-talk between the microbiome and host lipid metabolism. Females showed higher total and primary serum bile acids levels, independent of presence of microbiota. However, in presence of microbiota we observed higher secondary serum bile acid levels in females compared to males. Analysis of microbiota composition displayed sex-specific differences in Conv mice. Therefore, our data suggests that bile acids possibly play a role in the crosstalk between the microbiome and sex-specific regulation of lipid metabolism. In conclusion, our data shows that presence of the gut microbiota contributes to sex differences in lipid metabolism.

    On a collection of deep-water shrimp (Crustacea, Decapoda) from the Dutch Caribbean, with the description of a new species of Pseudocoutierea
    Olthof, Gabriël ; Becking, Leontine E. ; Fransen, Charles H.J.M. - \ 2018
    Zootaxa 4415 (2018)3. - ISSN 1175-5326 - p. 533 - 548.
    Crustacea - Decapoda - Deep reef - Dutch Caribbean - New records - New species - Pseudocoutierea
    A collection of shrimp from deep reefs in the Dutch Caribbean is described. Most material originates from the Bonaire deep reef expedition (2013) by Wageningen Marine Research of Wageningen University. Some additional material was available from dives on Curaçao (2014). A new species of Pseudocoutierea Holthuis was recognized in the material collected off Bonaire. The new species is described and illustrated and its position in the phylogeny of the genus Pseudocoutierea analyzed. A key to the species in the genus is presented.
    De Fransen haten hen om hun pulsjes
    Kraan, M.L. - \ 2018
    β2→1-fructans modulate the immune system in vivo in a microbiota-dependent and -independent fashion
    Fransen, Floris ; Sahasrabudhe, Neha M. ; Elderman, Marlies ; Bosveld, M. ; Aidy, Sahar El; Hugenholtz, F. ; Borghuis, Theo ; Kousemaker, Ben ; Winkel, Simon ; Gaast-de Jongh, Christa van der; Jonge, Marien I. de; Boekschoten, M.V. ; Smidt, H. ; Vos, Paul de - \ 2018
    Wageningen University
    Mus musculus - GSE94516 - PRJNA371228
    It has been shown in vitro that only specific dietary-fibers contribute to immunity but studies in vivo are not conclusive. Here we investigated degree of polymerization (DP) dependent effects of β2→1-fructans on immunity via microbiota-dependent and -independent effects. To this end, conventional or germ-free mice received short- or long-chain β2→1-fructan for 5 days. Immune cell populations in the spleen, mesenteric lymph nodes (MLN), and Peyer's patches (PPs) were analyzed with flow cytometry, genome-wide gene expression in the ileum was measured with microarray, and gut microbiota composition was analyzed with 16S rRNA sequencing of fecal samples. We found that β2→1-fructans modulated immunity by both microbiota and microbiota-independent effects. Moreover, effects were dependent on the chain-length of the β2→1-fructans type polymer. Both short- and long-chain β2→1-fructans enhanced T-helper 1 cells in Peyer's patches, whereas only short-chain β2→1-fructans increased regulatory T cells and CD11b-CD103- DCs in the MLN. A common feature after short- and long-chain β2→1-fructan treatment was enhanced Fut2 expression and other IL-22-dependent genes in the ileum of conventional mice. These effects were not associated with shifts in gut microbiota composition, or altered production of short-chain fatty acids. Both short- and long-chain β2→1-fructans also induced immune effects in germ-free animals, demonstrating direct effect independent from the gut microbiota. Also, these effects were dependent on the chain-length of the β2→1-fructans. Short-chain β2→1-fructan induced lower CD80 expression by CD11b-CD103- DCs in PPs, whereas long-chain β2→1-fructan specifically modulated B cell responses in germ-free mice. In conclusion, support of immunity is determined by the chemical structure of β2→1-fructans and is partially microbiota-independent.
    Aged gut microbiota contributes to systemical inflammaging after transfer to germ-free mice
    Fransen, Floris ; Beek, A.A. van; Borghuis, Theo ; Aidy, Sahar El; Hugenholtz, F. ; Gaast-de Jongh, Christa van der; Savelkoul, H.F.J. ; Jonge, Marien I. De; Boekschoten, M.V. ; Smidt, H. ; Faas, Marijke M. ; Vos, Paul de - \ 2018
    Wageningen University
    Mus musculus - GSE104063 - PRJNA408136
    Advanced age is associated with chronic low-grade inflammation, which is usually referred to as inflammaging. Elderly are also known to have an altered gut microbiota composition. However, whether inflammaging is a cause or consequence of an altered gut microbiota composition is not clear. In this study gut microbiota from young or old conventional mice was transferred to young germ-free mice. Four weeks after gut microbiota transfer immune cell populations in spleen, Peyer’s patches, and mesenteric lymph nodes from conventionalized germ-free mice were analyzed by flow cytometry. In addition, whole-genome gene expression in the ileum was analyzed by microarray. Gut microbiota composition of donor and recipient mice was analyzed with 16S rDNA sequencing. Here we show by transferring aged microbiota to young germ-free mice that certain bacterial species within the aged microbiota promote inflammaging. This effect was associated with lower levels of Akkermansia and higher levels of TM7 bacteria and Proteobacteria in the aged microbiota after transfer. The aged microbiota promoted inflammation in the small intestine in the germ-free mice and enhanced leakage of inflammatory bacterial components into the circulation was observed. Moreover, the aged microbiota promoted increased T cell activation in the systemic compartment. In conclusion, these data indicate that the gut microbiota from old mice contributes to inflammaging after transfer to young germ-free mice.
    Aged gut microbiota contributes to systemical inflammaging after transfer to germ-free mice
    Fransen, Floris ; Beek, Adriaan A. van; Borghuis, Theo ; Aidy, Sahar El; Hugenholtz, Floor ; Gaast - de Jongh, Christa van der; Savelkoul, Huub F.J. ; Jonge, Marien I. de; Boekschoten, Mark V. ; Smidt, Hauke ; Faas, Marijke M. ; Vos, Paul de - \ 2017
    Frontiers in Immunology 8 (2017). - ISSN 1664-3224
    Aging - Germ-free mice - Gut microbiome - Immune system - Inflammaging
    Advanced age is associated with chronic low-grade inflammation, which is usually referred to as inflammaging. Elderly are also known to have an altered gut microbiota composition. However, whether inflammaging is a cause or consequence of an altered gut microbiota composition is not clear. In this study, gut microbiota from young or old conventional mice was transferred to young germ-free (GF) mice. Four weeks after gut microbiota transfer immune cell populations in spleen, Peyer's patches, and mesenteric lymph nodes from conventionalized GF mice were analyzed by flow cytometry. In addition, whole-genome gene expression in the ileum was analyzed by microarray. Gut microbiota composition of donor and recipient mice was analyzed with 16S rDNA sequencing. Here, we show by transferring aged microbiota to young GF mice that certain bacterial species within the aged microbiota promote inflammaging. This effect was associated with lower levels of Akkermansia and higher levels of TM7 bacteria and Proteobacteria in the aged microbiota after transfer. The aged microbiota promoted inflammation in the small intestine in the GF mice and enhanced leakage of inflammatory bacterial components into the circulation was observed. Moreover, the aged microbiota promoted increased T cell activation in the systemic compartment. In conclusion, these data indicate that the gut microbiota from old mice contributes to inflammaging after transfer to young GF mice.
    The impact of gut microbiota on gender-specific differences in immunity
    Fransen, Floris ; Beek, Adriaan A. van; Borghuis, Theo ; Meijer, Ben ; Hugenholtz, Floor ; Gaast-de Jongh, Christa van der; Savelkoul, Huub F. ; Jonge, Marien I. de; Faas, Marijke M. ; Boekschoten, Mark V. ; Smidt, Hauke ; Aidy, Sahar El ; Vos, Paul de - \ 2017
    Frontiers in Immunology 8 (2017). - ISSN 1664-3224 - 14 p.
    Gender - Germ-free mice - Gut microbiota - Immunity - Inflammation

    Males and females are known to have gender-specific differences in their immune system and gut microbiota composition. Whether these differences in gut microbiota composition are a cause or consequence of differences in the immune system is not known. To investigate this issue, gut microbiota from conventional males or females was transferred to germ-free (GF) animals of the same or opposing gender. We demonstrate that microbiota-independent gender differences in immunity are already present in GF mice. In particular, type I interferon signaling was enhanced in the intestine of GF females. Presumably, due to these immune differences bacterial groups, such as Alistipes, Rikenella, and Porphyromonadaceae, known to expand in the absence of innate immune defense mechanism were overrepresented in the male microbiota. The presence of these bacterial groups was associated with induction of weight loss, inflammation, and DNA damage upon transfer of the male microbiota to female GF recipients. In summary, our data suggest that microbiota-independent gender differences in the immune system select a gender-specific gut microbiota composition, which in turn further contributes to gender differences in the immune system.

    Gezondheidsmakelaars verbeteren het Gezondheidsbevorderend Systeem van hun wijk of gemeente
    Fransen, G.A.J. ; Riet, A. v.d.; Ham, L.T.J. v.d.; Wagemakers, Annemarie ; Molleman, G.R.M. - \ 2017
    In: Nederlands Congres Volksgezondheid 2017 - De professional maakt het verschil. -
    Achtergrond en doelstelling:
    Sinds 2009 zijn er gezondheidsmakelaars werkzaam bij GGD Gelderland-Zuid, iedere gezondheidsmakelaar heeft zijn eigen wijken of gemeenten. Zij hebben als taak om het GezondheidsBevorderend Systeem (GBS) in hun gemeente/wijk te verbeteren, zoals beschreven in ons logisch model (gepresenteerd op NCVGZ 2015). Het doel van dit onderzoek is om een monitoringsinstrument te ontwikkelen voor het meten van het GBS en een eerste meting uit te voeren, zodat we inzicht krijgen in hoe “sterk” het GBS van iedere gemeente/wijk is.

    Methode:
    8 variabelen zijn benoemd om het GBS te operationaliseren: samenwerking; samenhang; duurzaamheid; integrale aanpak; draagvlak; aanpak gebaseerd op een gezondheidsprofiel; in staat zijn tussentijdse resultaten zichtbaar te maken; bereik einddoelgroep. Vanuit literatuurstudie is gezocht naar valide instrumenten om deze variabelen te meten en te kwantificeren en is een monitoringsinstrument ontwikkeld.
    Per gemeente/wijk zijn 8 stakeholders uitgenodigd om de vragenlijst in te vullen: de gezondheidsmakelaar, ambtenaar volksgezondheid, huisarts, wijkverpleegkundige, welzijn, sportservice, fysiotherapeut en adviseur gezonde school. De meting vindt nu plaats in het hele werkgebied van GGD Gelderland-Zuid (16 gemeenten waaronder Nijmegen (8 wijken) en Wijchen (2 wijken)). Naast de vragenlijst vindt er documentanalyse plaats en gesprekken met gezondheidsmakelaar en evt andere stakeholders om de resultaten goed te kunnen duiden en in de context te beoordelen.

    Resultaten:
    Per gemeente/wijk zal een factsheet gemaakt worden met daarop de scores per variabele (gemiddelde van de 8 stakeholders). De resultaten verwachten wij in februari 2017.

    Conclusie en aanbevelingen: Met dit monitoringsinstrument zijn we in staat om de sterke van het GBS te meten, waarmee de gezondheidsmakelaar beter kan bepalen waar het GBS van zijn/haar gemeente versterkt kan worden en hij/zij op zou kunnen inzetten. Daarnaast dragen deze metingen bij aan het zichtbaar maken van de resultaten van de gezondheidsmakelaars.
    β2→1-fructans modulate the immune system in vivo in a microbiota-dependent and -independent fashion
    Fransen, Floris ; Sahasrabudhe, Neha M. ; Elderman, Marlies ; Bosveld, Margaret ; Aidy, Sahar El; Hugenholtz, Floor ; Borghuis, Theo ; Kousemaker, Ben ; Winkel, Simon ; Gaast-de Jongh, Christa van der; Jonge, Marien I. de; Boekschoten, Mark V. ; Smidt, Hauke ; Schols, Henk A. ; Vos, Paul de - \ 2017
    Frontiers in Immunology 8 (2017). - ISSN 1664-3224
    Germ-free mice - Gut microbiota - Mucosal immunology - Prebiotics - β2→1-fructans
    It has been shown in vitro that only specific dietary fibers contribute to immunity, but studies in vivo are not conclusive. Here, we investigated degree of polymerization (DP) dependent effects of β2→1-fructans on immunity via microbiota-dependent and -independent effects. To this end, conventional or germ-free mice received short- or long-chain β2→1-fructan for 5 days. Immune cell populations in the spleen, mesenteric lymph nodes (MLNs), and Peyer's patches (PPs) were analyzed with flow cytometry, genome-wide gene expression in the ileum was measured with microarray, and gut microbiota composition was analyzed with 16S rRNA sequencing of fecal samples. We found that β2→1-fructans modulated immunity by both microbiota and microbiota-independent effects. Moreover, effects were dependent on the chain-length of the β2→1-fructans type polymer. Both short- and long-chain β2→1-fructans enhanced T-helper 1 cells in PPs, whereas only short-chain β2→1-fructans increased regulatory T cells and CD11b-CD103- dendritic cells (DCs) in the MLN. A common feature after short- and long-chain β2→1-fructan treatment was enhanced 2-alpha-l-fucosyltransferase 2 expression and other IL-22-dependent genes in the ileum of conventional mice. These effects were not associated with shifts in gut microbiota composition, or altered production of short-chain fatty acids. Both short- and long-chain β2→1-fructans also induced immune effects in germ-free animals, demonstrating direct effect independent from the gut microbiota. Also, these effects were dependent on the chain-length of the β2→1-fructans. Short-chain β2→1-fructan induced lower CD80 expression by CD11b-CD103- DCs in PPs, whereas long-chain β2→1-fructan specifically modulated B cell responses in germ-free mice. In conclusion, support of immunity is determined by the chemical structure of β2→1-fructans and is partially microbiota independent.
    Microbial stimulation of different Toll-like receptor signalling pathways induces diverse metabolic programmes in human monocytes
    Lachmandas, Ekta ; Boutens, Lily ; Ratter, Jacqueline M. ; Hijmans, Anneke ; Hooiveld, Guido J. ; Joosten, Leo A.B. ; Rodenburg, Richard J. ; Fransen, Jack A.M. ; Houtkooper, Riekelt H. ; Crevel, R. van; Netea, Mihai G. ; Stienstra, R. - \ 2016
    Nature Microbiology 2 (2016). - ISSN 2058-5276

    Microbial stimuli such as lipopolysaccharide (LPS) induce robust metabolic rewiring in immune cells known as the Warburg effect. It is unknown whether this increase in glycolysis and decrease in oxidative phosphorylation (OXPHOS) is a general characteristic of monocytes that have encountered a pathogen. Using CD14+ monocytes from healthy donors, we demonstrated that most microbial stimuli increased glycolysis, but that only stimulation of Toll-like receptor (TLR) 4 with LPS led to a decrease in OXPHOS. Instead, activation of other TLRs, such as TLR2 activation by Pam3CysSK4 (P3C), increased oxygen consumption and mitochondrial enzyme activity. Transcriptome and metabolome analysis of monocytes stimulated with P3C versus LPS confirmed the divergent metabolic responses between both stimuli, and revealed significant differences in the tricarboxylic acid cycle, OXPHOS and lipid metabolism pathways following stimulation of monocytes with P3C versus LPS. At a functional level, pharmacological inhibition of complex I of the mitochondrial electron transport chain diminished cytokine production and phagocytosis in P3C- but not LPS-stimulated monocytes. Thus, unlike LPS, complex microbial stimuli and the TLR2 ligand P3C induce a specific pattern of metabolic rewiring that involves upregulation of both glycolysis and OXPHOS, which enables activation of host defence mechanisms such as cytokine production and phagocytosis.

    Paris Agreement climate proposals need a boost to keep warming well below 2 °c
    Rogelj, Joeri ; Elzen, Michel Den; Höhne, Niklas ; Fransen, Taryn ; Fekete, Hanna ; Winkler, Harald ; Schaeffer, Roberto ; Sha, Fu ; Riahi, Keywan ; Meinshausen, Malte - \ 2016
    Nature 534 (2016)7609. - ISSN 0028-0836 - p. 631 - 639.

    The Paris climate agreement aims at holding global warming to well below 2 degrees Celsius and to "pursue efforts" to limit it to 1.5 degrees Celsius. To accomplish this, countries have submitted Intended Nationally Determined Contributions (INDCs) outlining their post-2020 climate action. Here we assess the effect of current INDCs on reducing aggregate greenhouse gas emissions, its implications for achieving the temperature objective of the Paris climate agreement, and potential options for overachievement. The INDCs collectively lower greenhouse gas emissions compared to where current policies stand, but still imply a median warming of 2.6-3.1 degrees Celsius by 2100. More can be achieved, because the agreement stipulates that targets for reducing greenhouse gas emissions are strengthened over time, both in ambition and scope. Substantial enhancement or over-delivery on current INDCs by additional national, sub-national and non-state actions is required to maintain a reasonable chance of meeting the target of keeping warming well below 2 degrees Celsius.

    First Complete Genome Sequence of the Dutch Veterinary Coxiella burnetii Strain NL3262, Originating from the Largest Global Q Fever Outbreak, and Draft Genome Sequence of Its Epidemiologically Linked Chronic Human Isolate NLhu3345937
    Kuley, R. ; Smith, H.E. ; Janse, I. ; Harders, F.L. ; Baas, F. ; Schijlen, Elio ; Nabuurs-Fransen, M.H. ; Smits, M.A. ; Roest, H.I.J. ; Bossers, A. - \ 2016
    Genome Announcements 4 (2016)2. - ISSN 2169-8287 - 2 p.
    The largest global Q fever outbreak occurred in The Netherlands during 2007 to 2010. Goats and sheep were identified as the major sources of disease. Here, we report the first complete genome sequence of Coxiella burnetii goat outbreak strain NL3262 and that of an epidemiologically linked chronic human strain, both having the outbreak-related CbNL01 multilocus variable-number tandem-repeat analysis (MLVA) genotype
    Mitochondrial dysfunction in primary human fibroblasts triggers an adaptive cell survival program that requires AMPK-alpha
    Distelmaier, F. ; Valsecchi, F. ; Liemburg-Apers, D. ; Lebiedzinska, M. ; Rodenburg, R. ; Heil, S. ; Keijer, J. ; Fransen, J. ; Imamura, H. ; Danhauser, K. ; Seibt, A. ; Viollet, B. ; Gellerich, F. ; Smeitink, J. ; Wieckowski, M. ; Willems, P. ; Koopman, W.J.H. - \ 2015
    Biochimica et Biophysica Acta. Molecular Basis of Disease 1852 (2015)3. - ISSN 0925-4439 - p. 529 - 540.
    complex-i deficiency - ubiquinone oxidoreductase deficiency - activated protein-kinase - respiratory-chain dysfunction - human nadh - oxidative-phosphorylation - energy-metabolism - mammalian-cells - atp production - cancer-cells
    Dysfunction of complex I (CI) of the mitochondrial electron transport chain (ETC) features prominently in human pathology. Cell models of ETC dysfunction display adaptive survival responses that still are poorly understood but of relevance for therapy development. Here we comprehensively examined how primary human skin fibroblasts adapt to chronic CI inhibition. CI inhibition triggered transient and sustained changes in metabolism, redox homeostasis and mitochondrial (ultra)structure but no cell senescence/death. CI-inhibited cells consumed no oxygen and displayed minor mitochondrial depolarization, reverse-mode action of complex V, a slower proliferation rate and futile mitochondrial biogenesis. Adaptation was neither prevented by antioxidants nor associated with increased PGC1-a/SIRT1/mTOR levels. Survival of CI-inhibited cells was strictly glucose-dependent and accompanied by increased AMPK-a phosphorylation, which occurred without changes in ATP or cytosolic calcium levels. Conversely, cells devoid of AMPK-a died upon CI inhibition. Chronic CI inhibition did not increase mitochondrial superoxide levels or cellular lipid peroxidation and was paralleled by a specific increase in SOD2/GR, whereas SOD1/CAT/Gpx1/Gpx2/Gpx5 levels remained unchanged. Upon hormone stimulation, fully adapted cells displayed aberrant cytosolic and ER calcium handling due to hampered ATP fueling of ER calcium pumps. It is concluded that CI dysfunction triggers an adaptive program that depends on extracellular glucose and AMPK-a. This response avoids cell death by suppressing energy crisis, oxidative stress induction and substantial mitochondrial depolarization
    A short assessment of health literacy (SAHL) in the Netherlands
    Pander Maat, Henk ; Essink-Bot, Marie Louise ; Leenaars, Karlijn E.F. ; Fransen, Mirjam P. - \ 2014
    BMC Public Health 14 (2014)1. - ISSN 1471-2458
    Health literacy - Reading comprehension - Testing - Word recognition

    Background: An earlier attempt to adapt the REALM (Rapid Estimate of Adult Literacy in Medicine) word recognition test to Dutch was not entirely successful due to ceiling effects. In contrast to REALM, the Short Assessment of Health Literacy (SAHL) assesses both word recognition and comprehension in the health domain. The aim of this study was to design, test and validate a SAHL for Dutch patients (SAHL-D).

    Methods. We pretested 95 health-related terms (n = 127) and selected 33 best performing items for validation in a quantitative survey (n = 329). For each item, a correct recognition (1 point) and comprehension (1 point) contributed to the total score (scale 0-66). Internal consistency was assessed using Cronbach's alpha. Construct validity was examined by analyzing association patterns of SAHL-D with educational level, objective and subjective health literacy, prose literacy, and vocabulary. Receiver operating characteristic (ROC) curves, with prose literacy as the reference standard, determined optimal cut-off scores.

    Results: Cronbach's alpha was 0.77 for recognition, 0.79 for comprehension, and 0.86 for the total score. Scores significantly differed substantially by educational level. Association patterns mostly confirmed a priori expectations in direction and strength, thereby supporting the construct validity of the SAHL-D. The optimal cut-off scores for differentiating between adequate and low literacy lie between 52.5 and 55.5. A shorter SAHL-D version presenting 22 terms offers a comparable prediction performance.

    Conclusion: The results provide positive evidence for the reliability and validity of the SAHL-D. The SAHL-D can be applied to analyze the role of health literacy in health and healthcare, and for the development and evaluation of targeted interventions.

    Adherence to dietary guidelines and cardiovascular disease risk in the EPIC-NL cohort
    Struijk, E.A. ; May, A.M. ; Wezenbeek, N.L.W.J. ; Fransen, H. ; Soedamah-Muthu, S.S. ; Geelen, A. ; Boer, J. ; Schouw, Y.T. van der; Bueno de Mesquita, H.B. ; Beulens, J.W.J. - \ 2014
    International Journal of Cardiology 176 (2014)2. - ISSN 0167-5273 - p. 354 - 359.
    coronary-heart-disease - major chronic disease - systematic analysis - for-americans - global burden - style diet - 21 regions - women - men - questionnaire
    Background Global and national dietary guidelines have been created to lower chronic disease risk. The aim of this study was to assess whether greater adherence to the WHO guidelines (Healthy Diet Indicator (HDI)); the Dutch guidelines for a healthy diet (Dutch Healthy Diet-index (DHD-index)); and the Dietary Approaches to Stop Hypertension (DASH) diet was associated with a lower risk of cardiovascular disease (CVD), coronary heart disease (CHD) or stroke. Methods A prospective cohort study was conducted among 33,671 healthy Dutch men and women aged 20–70 years recruited into the EPIC-NL study during 1993–1997. We used Cox regression adjusted for relevant confounders to estimate the hazard ratios per standard deviation increase in score and 95% confidence intervals (CI) of the associations between the dietary guidelines and CVD, CHD and stroke risk. Results After an average follow-up of 12.2 years, 2752 CVD cases were documented, including 1630 CHD cases and 527 stroke cases. We found no association between the HDI (0.98, 95% CI 0.94; 1.02) or DHD-index (0.96, 95% CI 0.92; 1.00) and CVD incidence. Similar results were found for these guidelines and CHD or stroke incidence. Higher adherence to the DASH diet was significantly associated with a lower CVD (0.92, 95% CI 0.89; 0.96), CHD (0.91, 95% CI 0.86; 0.95), and stroke (0.90, 95% CI 0.82; 0.99) risk. Conclusion The HDI and the DHD-index were not associated with CVD risk, while the DASH diet was significantly associated with a lower risk of developing CVD, CHD and stroke.
    The emissions gap report 2013 - A UNEP Synthesis Report
    Elzen, M.G.J. den; Fransen, T. ; Rogner, H.H. ; Luderer, G. ; Rogelj, J. ; Schaeffer, R. ; Neufeldt, H. ; Hoehne, N.E. ; Morgan, J. ; Olhoff, A. - \ 2013
    Nairobi, Kenya : United Nations Environment Programme - ISBN 9789280733532 - 45
    Recensie : Alfons Fransen, Dijk onder spanning. De ecologische, politieke en financiële geschiedenis van de Diemerdijk bij Amsterdam, 1591-1864
    Cruijningen, P.J. van - \ 2013
    Holland: regionaal-historisch tijdschrift 2013 (2013). - ISSN 0166-2511
    The Dutch Q fever outbreak in perspective: Genotyping as a tool for source tracing and epidemiological investigation
    Tilburg, J.H.H.C. ; Roest, H.I.J. ; Nabuurs-Fransen, M.H. ; Horrevorts, A.M. ; Klaassen, C.H.W. - \ 2013
    Bodemleven en organische stof, hoekstenen van een gezonde bodem
    Fransen, N. ; Os, G.J. van - \ 2013
    Fruitteelt-nieuws 2013 (2013)26. - p. 10 - 10.
    Leidraad beheersing eikenprocessierups : update 2013
    Fransen, J.J. ; Alterra - Centrum Landschap, - \ 2013
    Wageningen : Nederlandse Voedsel- en Warenautoriteit/Alterra - 51
    thaumetopoea processionea - insecten - insectenplagen - plagenbestrijding - openbaar groen - volksgezondheid - bestrijdingsprogramma - besluitvorming - monitoring - nederland - thaumetopoea processionea - insects - insect pests - pest control - public green areas - public health - control programmes - decision making - monitoring - netherlands
    De beheersing van de eikenprocessierups is geen eenvoudige opgave. Om gezondheidsklachten te voor- kómen blijkt het in de praktijk niet eenvoudig op het juiste moment op de meest adequate manier op te treden. Allereerst moet men een antwoord hebben op de twee vragen: Waar is eikenprocessierups aanwezig in mijn beheersgebied? Treedt eikenprocessierups in hoeveelheden op die overlast kunnen veroorzaken? Voor beantwoording van deze vragen spelen waarnemen en registreren een belangrijke rol. Vervolgens zal men een afweging moeten maken welke beheersingsmethoden men gaat toepassen waarbij ongewenste ecologische effecten vermeden moeten worden. Met deze geactualiseerde leidraad worden bouwstenen voor de professionele beheerders aangereikt om goede beheerkeuzen te maken. Het hart van de leidraad bestaat uit een stappenplan. Door dit stappenplan te volgen kan men komen tot een afgewogen en verantwoord beheer, waarbij men streeft naar een ecologisch duurzaam evenwicht met zo min mogelijk overlast voor mens en dier.
    Stadsklimaat ontwerpen
    Lenzholzer, S. - \ 2013
    In: Almanak 2012 / Platteeuw, S., Widdershoven, M.H., Berg, S.J.D., Borsje, J., Fransen, M., Wageningen : Stichting Genius Loci - p. 50 - 53.
    Genotyping Reveals the Presence of a Predominant Genotype of Coxiella burnetii in Consumer Milk Products
    Tilburg, J.J.H.C. ; Roest, H.I.J. ; Nabuurs-Fransen, M.H. ; Horrevorts, A.M. ; Klaassen, C.H.W. - \ 2012
    Journal of Clinical Microbiology 50 (2012)6. - ISSN 0095-1137 - p. 2156 - 2158.
    q-fever
    Real-time PCR shows the widespread presence of Coxiella burnetii DNA in a broad range of commercially available milk and milk products. MLVA genotyping shows that this is the result of the presence of a predominant C. burnetii genotype in the dairy cattle population.
    Letter to the editor: Epidemic Genotype of Coxiella burnetii among Goats, Sheep, and Humans in the Netherlands
    Tilburg, J.J.H.C. ; Roest, H.I.J. ; Buffet, S. ; Nabuurs-Fransen, M.H. ; Horrevorts, A.M. ; Raoult, D. ; Klaassen, C.H.W. - \ 2012
    Emerging Infectious Diseases 18 (2012)5. - ISSN 1080-6040 - p. 887 - 889.
    q-fever outbreak
    Genotypic Diversity of Coxiella burnetii in the 2007-2010 Q Fever Outbreak Episodes in The Netherlands
    Tilburg, J.J.H.C. ; Rossen, J.W.A. ; Hannen, E.J. van; Melchers, W.J.G. ; Hermans, M.H.A. ; Bovenkamp, J. van de; Roest, H.I.J. ; Bruin, A. de; Nabuurs-Fransen, M.H. ; Horrevorts, A.M. ; Klaassen, C.H.W. - \ 2012
    Journal of Clinical Microbiology 50 (2012)3. - ISSN 0095-1137 - p. 1076 - 1078.
    pcr
    The genotypic diversity of Coxiella burnetii in clinical samples obtained from the Dutch Q fever outbreak episodes of 2007-2010 was determined by using a 6-locus variable-number tandem repeat analysis panel. The results are consistent with the introduction of one founder genotype that is gradually diversifying over time while spreading throughout The Netherlands.
    Analyse luchtsysteem Marjoland IV
    Bontsema, J. ; Baas, R. ; Fransen, J. ; Voogt, J.O. ; Weel, P.A. van - \ 2012
    Wageningen : Wageningen UR Glastuinbouw (Rapporten WUR GTB 1171) - 118
    kastechniek - binnenklimaat - temperatuur - geconditioneerde teelt - cultuurmethoden - rozen - nederland - glastuinbouw - klimaatregeling - greenhouse technology - indoor climate - temperature - conditioned cultivation - cultural methods - roses - netherlands - greenhouse horticulture - air conditioning
    Bij Marjoland in Waddinxveen is een installatie aangebracht waarmee via slurven een mengsel van opgewarmde buitenlucht en gecirculeerde kaslucht onder het gewas wordt geblazen. Daarmee hoopt men kleinere temperatuurverschillen in de kas te krijgen en vocht op een goedkopere wijze af te voeren dan met een minimum buis. Uit metingen bleek dat de horizontale temperatuurverschillen veroorzaakt werden door een koude luchtstroom boven het doek die niet met de luchtblaasinstallatie gecompenseerd konden worden, maar wel met verticale schotten boven het schermdoek. Na deze ingreep is geleidelijk de verhouding kaslucht en buitenlucht zodanig gewijzigd, dat er steeds meer buitenlucht werd toegevoerd. Daarmee kon nagenoeg altijd het vochtdeficit boven 2,0 g/kg worden gehouden. Afhankelijk van de buitencondities werd 60 g/m2kas/uur vocht afgevoerd. Er was weinig energie nodig voor de ventilatoren en voor het opwarmen van de buitenlucht. De minimum buis kon 8 graden lager en de rookgaskoeler van de WKK werd beter benut.
    Molecular epidemiology of Coxiella burnetii from ruminants in Q fever outbreak, the Netherlands.
    Roest, H.I.J. ; Ruuls, R.C. ; Tilburg, J.H.H.C. ; Nabuurs-Fransen, M.H. ; Klaassen, C.H.W. ; Vellema, P. ; Brom, R. Van den; Dercksen, D. ; Wouda, W. ; Spierenburg, M. ; Spek, A.N. Van der; Buijs, R. ; Willemsen, P.T.J. - \ 2011
    Emerging Infectious Diseases 17 (2011)4. - ISSN 1080-6040 - p. 668 - 675.
    goats - history
    Q fever is a zoonosis caused by the bacterium Coxiella burnetii. One of the largest reported outbreaks of Q fever in humans occurred in the Netherlands starting in 2007; epidemiologic investigations identified small ruminants as the source. To determine the genetic background of C. burnetii in domestic ruminants responsible for the human Q fever outbreak, we genotyped 126 C. burnetii–positive samples from ruminants by using a 10-loci multilocus variable-number tandem-repeat analyses panel and compared them with internationally known genotypes. One unique genotype predominated in dairy goat herds and 1 sheep herd in the human Q fever outbreak area in the south of the Netherlands. On the basis of 4 loci, this genotype is similar to a human genotype from the Netherlands. This finding strengthens the probability that this genotype of C. burnetii is responsible for the human Q fever epidemic in the Netherlands
    Motieven voor (non) participatie in leefstijlinterventie van lage SES in de eerste lijn. Poster presentatie 2
    Abdesslem, F. ; Wel, M. van der; Fransen, G. ; Vaandrager, L. - \ 2011
    In: Nederlands Congres Volksgezondheid 2011 on Duurzame Gezondheid, Amsterdam, The Netherlands, 6-7 April 2011. - - p. 63 - 63.
    Opgelet: teken en processierupsen
    Vliet, Arnold van - \ 2010
    insect pests - trees - pest control
    Teken en eikenprocessierupsen zijn in opmars. Ook in eigen achtertuin kan het barsten van de teken, ontdekte de Wageningse onderzoeker Arnold van Vliet. We weten eigenlijk nog zo weinig van teken, zegt hij. Joke Fransen van de Plantenziektenkundige Dienst zegt hetzelfde over de eikenprocessierups
    Samenwerking gebaat bij positieve houding omgeving
    Smit, A.B. - \ 2010
    In: Wil er snel gaan, ga alleen. Wil je ver komen, ga dan samen!. - Den Bosch : Hogeschool HAS Den Bosch / HAS Kennis Transfer, LEI Wageningen UR / AgroCenter voor Duurzaam Ondernemen, Groene Kennis Coöperatie - p. 14 - 15.
    ATP Changes the Fluorescence Lifetime of Cyan Fluorescent protein via an Interaction with His148
    Borst, J.W. ; Willemse, M. ; Slijkhuis, R. ; Krogt, G. ; Laptenok, S. ; Jalink, K. ; Wieringa, B. ; Fransen, J.A.M. - \ 2010
    PLoS ONE 5 (2010)11. - ISSN 1932-6203 - 7 p.
    energy-transfer - variant - fret - cell - spectroscopy - chromophore - binding - decays
    Recently, we described that ATP induces changes in YFP/CFP fluorescence intensities of Fluorescence Resonance Energy Transfer (FRET) sensors based on CFP-YFP. To get insight into this phenomenon, we employed fluorescence lifetime spectroscopy to analyze the influence of ATP on these fluorescent proteins in more detail. Using different donor and acceptor pairs we found that ATP only affected the CFP-YFP based versions. Subsequent analysis of purified monomers of the used proteins showed that ATP has a direct effect on the fluorescence lifetime properties of CFP. Since the fluorescence lifetime analysis of CFP is rather complicated by the existence of different lifetimes, we tested a variant of CFP, i.e. Cerulean, as a monomer and in our FRET constructs. Surprisingly, this CFP variant shows no ATP concentration dependent changes in the fluorescence lifetime. The most important difference between CFP and Cerulean is a histidine residue at position 148. Indeed, changing this histidine in CFP into an aspartic acid results in identical fluorescence properties as observed for the Cerulean fluorescent based FRET sensor. We therefore conclude that the changes in fluorescence lifetime of CFP are affected specifically by possible electrostatic interactions of the negative charge of ATP with the positively charged histidine at position 148. Clearly, further physicochemical characterization is needed to explain the sensitivity of CFP fluorescence properties to changes in environmental (i.e. ATP concentrations) conditions.
    Vrijwel alle onderzoeken positief - Special 'Het Nieuwe Telen'
    Marcelis, L.F.M. ; Dueck, T.A. ; Noort, F.R. van; Kromwijk, J.A.M. ; Labrie, C.W. ; Zwart, H.F. de; Fransen, J. ; Mei, M. van der; Beukel, J. van den - \ 2010
    Vakblad voor de Bloemisterij 65 (2010)23. - ISSN 0042-2223 - p. 36 - 37.
    tuinbouw - kassen - gewaskwaliteit - proeven - landbouwkundig onderzoek - bereikt resultaat - sierplanten - snijbloemen - energiebesparing - glastuinbouw - kastechniek - horticulture - greenhouses - crop quality - trials - agricultural research - achievement - ornamental plants - cut flowers - energy saving - greenhouse horticulture - greenhouse technology
    Uit vrijwel alle proeven met Het Nieuwe telen blijkt dat er nog veel energie te besparen valt. Bovendien wordt de kwaliteit van de producten er niet minder op. De resultaten van de diverse onderzoeken op een rij.
    The influence of regulatory fit on evaluation and intentions to buy genetically modified foods: The mediating role of social identification
    Fransen, M.L. ; Reinders, M.J. ; Bartels, J. ; Maassen, R.L. - \ 2010
    Journal of Marketing Communications 16 (2010)1. - ISSN 1352-7266 - p. 5 - 20.
    The present study examines how communicated messages could be effective in affecting consumers' attitudes and behavioural intentions regarding genetically modified (GM) foods. Based on Regulatory Focus Theory, it was hypothesized that exposure to a communication message matching a consumer's regulatory orientation (i.e. regulatory fit) leads to more positive attitudes and greater willingness to buy GM foods than exposure to a communication message that does not match with consumer's regulatory orientation. Moreover, it was expected that social identification with the consumer of GM foods mediates the relationship between both regulatory fit and attitudes and regulatory fit and behavioural intentions. The results support our hypotheses by showing that communicated messages that are congruent (vs incongruent) with consumers' regulatory orientations enhanced social identification with the consumer of GM foods, which, in turn, positively affected attitudes and behavioural intentions. Management implications for designing informative messages regarding GM foods are discussed.
    "Wil je snel gaan, ga alleen, wil je ver komen ga dan samen" : onderwijsdag ondernemerschap 21 januari 2010
    Fransen, L. ; Hamers-van den Berkmortel, N.W.T.H. van den - \ 2010
    Den Bosch [etc.] : HAS [etc.] - 47
    onderwijs - ondernemerschap - samenwerking - coöperatieve activiteiten - kennis - innovaties - ketenmanagement - communities of practice - kennisoverdracht - bijscholing - education - entrepreneurship - cooperation - cooperative activities - knowledge - innovations - supply chain management - communities of practice - knowledge transfer - continuing training
    Overzicht van diverse vormen van samenwerking en samenwerkingsprojecten die aan bod zijn gekomen tijdens de Onderwijsdag Ondernemerschap
    Environmental impact assessment of the pangasius sector in the Mekong Delta
    Bosma, R.H. ; Hanh, C.T.T. ; Potting, J. ; Anh, P.T. ; Dung, V.V. ; Fransen, M. ; Hien, H.T.T. ; Hong, P.T.T. ; Minh, N.T. ; Tuan, T.T. ; Phong, L.T. ; Vuong, D.Q.T. ; Yen, T. ; Ut, V.N. - \ 2009
    Wageningen : Wageningen University - 57
    aquacultuur - vis - milieueffect - milieuafbraak - milieubeheer - bedrijfsvoering - vietnam - aquacultuur en milieu - milieu-analyse - economische aspecten - aquaculture - fish - environmental impact - environmental degradation - environmental management - management - vietnam - aquaculture and environment - environmental analysis - economic aspects
    In the past seven years the export of white pangasius fillets grew fast. The culture method shifted to intensive production of striped catfish (Ca Tra) in deep ponds because this is more efficient than the pen and cage culture of Ca Basa. Today, striped catfish comprises more than 90 % of the culture. The increased production was achieved by producers investing in large ponds. The market chain is gearing towards vertical integration. Most farms keep fish at relatively high densities of 15 to 25 fish/m3 in ponds having a depth of up to 4m, and are advised to exchange daily 20 to 40% of the water. The sustainability of the sector is threatened due to the increased environmental pressure, and hampered by the growing cost of inputs and reduced farm-gate prices of the fish. The Environmental Impact Assessment (EIA) intends to identify measures for preventing or mitigating the environmental impacts of catfish culture in the Mekong Delta. The EIA was a seven-step process during which we interacted twice with part of the main stakeholders. To build trust among the stakeholders from the sector, we conducted the scoping and goal setting with them.
    Effect van "Ruimte voor Geo-informatie" op GIScience in Nederland : eindrapport RGI-402
    Veller, M.G.P. van; Fransen, H. ; Duizendstraal, M.B. ; Gerritsma, W. - \ 2009
    Wageningen : Bibliotheek Wageningen UR - 39
    geografische informatiesystemen - periodieken - dissertaties - evaluatie - prestatieniveau - bibliothecarisambt - wetenschap - geographical information systems - periodicals - theses - evaluation - performance - librarianship - science
    This report describes bibliometric analyses of the scientific output of GIScience in the Netherlands over the period 1999-2007. The bibliometric analyses have been based upon bibliographic data from articles published in 12 peer reviewed GIScience journals, articles in two professional journals and PhD theses which have been published at Dutch universities. Based upon these sources information is obtained for the publication output and citation impact of the Netherlands in an international context, the (inter)national co-operation of Dutch organizations with other organizations when publishing on geographic information systems in scientific literature and information on both scientific output in GIScience as well as related scientific disciplines for authors from the Netherlands. The bibliometric results obtained for GIScience are discussed in relation to science as a whole for the Netherlands.
    Inherited complex I deficiency is associated with faster protein diffusion in the matrix of moving mitochondria
    Koopman, W.J.H. ; Distelmaier, F. ; Hink, M.A. ; Verkaart, S. ; Wijers, M. ; Fransen, J. ; Smeitink, J.A.M. ; Willems, P.H.G.M. - \ 2008
    American Journal of Physiology: Cell Physiology 294 (2008)5. - ISSN 0363-6143 - p. C1124 - C1132.
    fluorescence correlation spectroscopy - ubiquinone oxidoreductase deficiency - leigh-syndrome - human nadh - oxidative-phosphorylation - correlation microscopy - skin fibroblasts - steady-state - mutations - motility
    Mitochondria continuously change shape, position, and matrix configuration for optimal metabolite exchange. It is well established that changes in mitochondrial metabolism influence mitochondrial shape and matrix configuration. We demonstrated previously that inhibition of mitochondrial complex I (CI or NADH: ubiquinone oxidoreductase) by rotenone accelerated matrix protein diffusion and decreased the fraction and velocity of moving mitochondria. In the present study, we investigated the relationship between inherited CI deficiency, mitochondrial shape, mobility, and matrix protein diffusion. To this end, we analyzed fibroblasts of two children that represented opposite extremes in a cohort of 16 patients, with respect to their residual CI activity and mitochondrial shape. Fluorescence correlation spectroscopy (FCS) revealed no relationship between residual CI activity, mitochondrial shape, the fraction of moving mitochondria, their velocity, and the rate of matrix-targeted enhanced yellow fluorescent protein (mitoEYFP) diffusion. However, mitochondrial velocity and matrix protein diffusion in moving mitochondria were two to three times higher in patient cells than in control cells. Nocodazole inhibited mitochondrial movement without altering matrix EYFP diffusion, suggesting that both activities are mutually independent. Unexpectedly, electron microscopy analysis revealed no differences in mitochondrial ultrastructure between control and patient cells. It is discussed that the matrix of a moving mitochondrion in the CI-deficient state becomes less dense, allowing faster metabolite diffusion, and that fibroblasts of CI-deficient patients become more glycolytic, allowing a higher mitochondrial velocity.
    Leidraad beheersing eikenprocessierups
    Fransen, J.J. ; Groenendijk, D. ; Spijker, J.H. ; Stigter, H. - \ 2008
    Wageningen : Alterra [etc.] - 25
    thaumetopoea processionea - insecten - insectenplagen - plagenbestrijding - volksgezondheid - monitoring - nederland - groenbeheer - boomverzorging - openbaar groen - thaumetopoea processionea - insects - insect pests - pest control - public health - monitoring - netherlands - management of urban green areas - tree care - public green areas
    De beheersing van de eikenprocessierups is geen eenvoudige opgave. Het blijkt in de praktijk niet eenvoudig een juiste mix te vinden tussen het voorkómen van gezondheidsklachten, het vermijden van ongewenste ecologische effecten en het opzetten van een adequate monitoring en bestrijding van deze plaag. Met deze leidraad worden voor de professionele beheerders bouwstenen aangereikt om goede beheerkeuzen te maken. De huidige versie van de Leidraad is in voorjaar 2008 door een afvaardiging van de Expertgroep Eikenprocessierups geactualiseerd op basis van nieuwe inzichten en praktijkervaringen
    The development of a minimal intervention strategy to address overweight and obesity in adult primary care patients in The Netherlands
    Fransen, G.A.J. ; Hiddink, G.J. ; Koelen, M.A. ; Dis, S.J. van; Drenthen, A.J.M. ; Binsbergen, J.J. van; Woerkum, C.M.J. van - \ 2008
    Family Practice 25 (2008)S1. - ISSN 0263-2136 - p. i112 - i115.
    general-practice
    Background. Currently, overweight and obesity do not receive the attention they deserve from the Dutch GPs, mostly because of a lack of an effective intervention strategy to tackle this difficult health problem. Objective. To develop a minimal intervention strategy (MIS) addressing overweight and obesity among adult primary care patients, resulting in a prototype. Methods. Following the intervention mapping protocol, the MIS is based on literature study, existing interventions, psychosocial theories, stakeholder interviews and a questionnaire study among stakeholders. This led to the development of a prototype of the MIS materials: a screening flow chart and a treatment flow chart, a manual and patient education materials. A pre-test among 42 general practitioners and practice nurses was conducted to investigate the usefulness of the MIS materials at first sight. Results. The stakeholder interviews and the questionnaire study resulted in insight on what the MIS should look like. For instance, the stakeholders indicated that the treatment needs to focus on helping patients to eat more healthy and exercise more, using techniques like motivational interviewing. The pre-test showed that most participants were enthusiastic about the materials, although they made some suggestions on improvements. Conclusion. The MIS materials seem to be useful and promising. A future pilot test is needed to investigate its usefulness in daily practice and to further improve the materials in preparation for a process and effect evaluation
    De ontwikkeling van een minimale interventie strategie voor het aanpakken van overgewicht en obesitas in de huisartsenpraktijk
    Fransen, G.A.J. ; Hiddink, G.J. ; Koelen, M.A. ; Binsbergen, J.J. van; Woerkum, C.M.J. van - \ 2008
    Minimale interventie strategie voor volwassenen met overgewicht en obesitas : resultaten van de pilottest : MIS overgewicht & obesitas
    Fransen, G.A.J. ; Hiddink, G.J. ; Koelen, M.A. ; Dis, S.J. van; Drenthen, A.J.M. ; Binsbergen, J.J. van; Woerkum, C.M.J. van - \ 2008
    Wageningen : Wageningen Universiteit, Communicatiewetenschap - 80
    communicatie - voorlichting - overgewicht - obesitas - behandeling - medische behandeling - artsen - huisartsen - communication - extension - overweight - obesity - treatment - medical treatment - physicians - general practitioners
    Bibliometric analysis of the Netherlands Research School for the Socio-Economic and Natural Sciences of the Environment
    Gerritsma, W. ; Duizendstraal, M.B. ; Fransen, H. ; Loman, M.E. - \ 2007
    Wageningen : Wageningen UR Library - 25 p.
    'De Spanjaarden en Fransen verklaren ons voor gek' : duurmelken al flink ingeburgerd in Nederlandse geitenhouderij
    Hulst, M. van der - \ 2007
    Nieuwe oogst / LTO Noord. Editie Noord 3 (2007)7. - ISSN 1871-0875 - p. 10 - 11.
    geitenhouderij - geiten - melkproducerende dieren - geitenmelk - melken - melkproductie - lactatieduur - lactatie - productieve levensduur - goat keeping - goats - milk yielding animals - goat milk - milking - milk production - lactation duration - lactation - productive life
    In de Nederlandse geitenhouderij is het al duurmelken behoorlijk ingeburgerd. Wie een deel van zijn geiten jarenlang duurmelkt, zonder tussenkomst van een dracht, bespaart veel tijd
    Minimale interventie strategie voor volwassenen met overgewicht en obesitas. De ontwikkeling van een MIS voor het aanpakken van overgewicht en obesitas in de huisartsenpraktijk
    Fransen, G.A.J. ; Hiddink, G.J. ; Koelen, M.A. ; Dis, S.J. van; Drenthen, A.J.M. ; Binsbergen, J.J. van; Woerkum, C.M.J. van - \ 2007
    Wageningen : Wageningen Universiteit, Lsg. Communicatie en Innovatie Studies - 86 p.
    Releases of parasitoids (Ceranisus spp.) as biological control agents of western flower thrips (Frankliniella occidentalis) in experimental glasshouses
    Loomans, A.J.M. ; Tolsma, J. ; Fransen, J.J. ; Lenteren, J.C. van - \ 2006
    Bulletin of Insectology 59 (2006)2. - ISSN 1721-8861 - p. 85 - 97.
    Literatuurstudie en voorstudie veldonderzoek eikenprocessierups: monitoring, bestrijdingsstrategieën en neveneffecten
    Fransen, J.J. ; Stigter, H. ; Drijver, C.A. ; Koomen, I. ; Moraal, L.G. ; Spijker, J.H. - \ 2006
    Wageningen : Plantenziektenkundige Dienst - 82
    thaumetopoea processionea - insectenplagen - bomen - insectenbestrijding - biologische bestrijding - chemische bestrijding - thaumetopoea processionea - insect pests - trees - insect control - biological control - chemical control
    Er zijn diverse methoden om de populaties eikenprocessierups te beheersen en om de overlast zo veel mogelijk te beperken. Een methode die veelvuldig in 2005 is ingezet in gebieden met veel overlast is het bespuiten van de eiken met XenTari en Dimilin. De toepassing van middelen van chemische of biologische oorsprong in de groene ruimte moet met grote zorgvuldigheid gebeuren, om zo min mogelijk verstoring in de natuurlijke omgeving te weeg te brengen. Daarom is dit eerste oriënterend onderzoek opgezet waarin gekeken is naar mogelijke effecten van toepassing van deze middelen met behulp van veldwaarnemingen en literatuuronderzoek en naar de mogelijkheden van inzet van natuurlijke vijanden
    Report literature research geo-visualization and participatory spatial planning
    Bloemmen, M.H.I. ; Fransen, H. ; Hoogerwerf, T.C. ; Ligtenberg, A. ; Lammeren, R.J.A. van - \ 2005
    Wageningen : Alterra (Alterra-rapport 1147)
    geografische informatiesystemen - ruimtelijke ordening - participatie - literatuuroverzichten - grijze literatuur - geographical information systems - physical planning - participation - literature reviews - grey literature
    The use of geo-visualization for participatory planning purposes is a challenging field of research. Reason for this is that researchers involved with the subject currently lack a common rationale for the integration of the two complementary domains: participatory planning and geo-visualization. Consequently existing knowledge still needs to be extracted from various relevant sub-domains of research. Therefore a literature research was conducted to make an inventory of aspects that influence the application of visualization and communication tools in (generic) participative planning processes. This report describes the literature search, including a selection of sub-domains and literature sources, a discussion of the search strategy and the search results. Furthermore the report includes a discussion on the set-up and maintenance of an article repository in conjunction with an Endnote database in which the bibliographical information of the retrieved literature is stored. Finally some recommendations are provided
    Infections with helminths and/or protozoa in cats in animal shelters in the Netherlands
    Robben, S.R. ; Nobel, W.E. le; Dopfer, D.D.V. ; Hendrikx, W.M. ; Boersema, J.H. ; Fransen, F. ; Eysker, M. - \ 2004
    Tijdschrift voor Diergeneeskunde 129 (2004)1. - ISSN 0040-7453 - p. 2 - 6.
    katten - gezelschapsdieren - protozoëninfecties - protozoa - helminthosen - kattenziekten - infectieziekten - cats - pets - protozoal infections - protozoa - helminthoses - cat diseases - infectious diseases - dogs
    To determine the prevalence of infections with helminths and protozoa in cats in animal shelters, faecal samples from 305 cats from 22 animal shelters in the Netherlands were examined, using a centrifugation-sedimentation-flotation-technique. The association between potential risk factors and the occurrence of an infection was also tested. Infections with helminths and/or protozoa were found in 160 samples (52.5%). Toxocara cati was found in 86 cats (28.2%), Cystoisospora felis in 59 cats (19.3%), Cystoisospora rivolta in 43 cats (14.1%), Capillaria spp. in 34 cats (11.2%), Ancylostoma tubaeforma in 9 cats (3.0%), Taenia taeniaeformis in 9 cats (3.0%), Aelurostrongylus abstrusus in 8 cats (2.6%), Giardia intestinalis in 3 cats (1.0%), Dipylidium caninum in 2 cats (0.7%) and Toxoplasma gondii in 1 cat (0.3%). The highest prevalence was seen in kittens and stray cats. The main preventive factor against infection was a short stay in a shelter.
    Infections with endoparasites in dogs in Dutch animal shelters
    Nobel, W.E. le; Robben, S.R. ; Dopfer, D.D.V. ; Hendrikx, W.M. ; Boersema, J.H. ; Fransen, F. ; Eysker, M. - \ 2004
    Tijdschrift voor Diergeneeskunde 129 (2004)2. - ISSN 0040-7453 - p. 40 - 44.
    honden - gezelschapsdieren - infectieziekten - parasitosen - hondenziekten - dogs - pets - infectious diseases - parasitoses - dog diseases - netherlands - toxocara
    Faecal samples from 224 dogs from 23 animal shelters in the Netherlands were examined for endoparasites. In total 20.5% of the faecal sample were positive for helminth and/or protozoa infections. Eggs of Toxocara canis were found in 8.5% of the faecal samples. Other endoparasites found were Toxascaris leonina (0.5%), Trichuris vulpis (4.9%), Uncinaria stenocephala (2.2%), Dipylidium caninum (1.3%), Taenia spp. (0.5%), Cystoisospora canis (1.3%), and C. ohioensis (1.3%). Dogs younger than 1 year and stray dogs showed the highest prevalence of infection. T. vulpis was found more often in dogs from shelters with a high cleaning frequency.
    Biocontrol of whitefly using stabilised Aschersonia formulations : DIARP no 18/97 Dutch partner report
    Fransen, J.J. - \ 2003
    Aalsmeer : Applied Plant Research (PPO), Business Unit Glasshouse Horticulture (Internal report / Applied Plant Research (PPO), Business Unit Glasshouse Horticulture : 41001651) - 49
    Inventarisatie problemen met wol-, schild- en dopluizen in bloemisterijgewassen : literatuurstudie, praktijkinventarisatie en bestrijdingsproeven
    Boertjes, B.C. ; Fransen, J.J. ; Berg, T.J.M. van den; Kok, L. ; Overdevest, B.A.M. - \ 2003
    Aalsmeer : Praktijkonderzoek Plant & Omgeving, Business Unit Glastuinbouw (PPO 584) - 104
    coccoidea - homoptera - biologische bestrijding - chemische bestrijding - gewasbescherming - sierplanten - nederland - glastuinbouw - coccoidea - homoptera - biological control - chemical control - plant protection - ornamental plants - netherlands - greenhouse horticulture
    Veel van de in kassen voorkomende wol-, dop- en schildluizen tasten een breed scala aan siergewassen aan, zoals potplanten en kuipplanten, maar ook snijbloemen. De meest voorkomende wolluis in Nederlandse kassen is de citruswolluis, Planococcus citri. Daarnaast komen onder andere de langstaartwolluis, Pseudococcus longispinus, en de kortstaartwolluis, Pseudococcus viburni, voor. Wat betreft schildluizen zijn het vooral schildluizen in cymbidium, dit waren Boisduval schildluis, Diaspis boisduvalii, en Oleander schildluis, Aspidiotus nerii. Een dopluis-soort die tijdens de inventarisatie werd aangetroffen was de platte dopluis, Coccus hesperidum. Andere regelmatig voorkomende soorten in Nederlandse kassen zijn de halvebol-dopluis, Saissetia coffeae, en Saissetia oleae. In dit rapport wordt, na een beschrijving van de levenswijze van wol-, dop en schildluizen, de belangrijkste soorten apart besproken. Naast een literatuuronderzoek en een inventarisatie onder telers is onderzoek gedaan naar entomopathogene schimmels voor de bestrijding van dop- en schilluizen, chemische bestrijding van wolluis, chemische bestrijding van schildluis en biologische bestrijding van schildluis. De meest geschikte methode voor de praktijk lijkt een teelt waarbij het ene jaar gewas wordt opgebouwd en in mei en juni wordt gesnoeid, zodat in het tweede jaar veel bloemen worden geoogst. Een goede nachtvorstbescherming is dan zeer noodzakelijk!
    Inventarisatie problemen met wol-, schild- en dopluizen in bloemisterijgewassen
    Boertjes, B.C. ; Fransen, J.J. ; Marissen, N. - \ 2003
    Aalsmeer : Praktijkonderzoek Plant & Omgeving, Business Unit Glastuinbouw - 51
    pseudococcidae - coccidae - sierplanten - glastuinbouw - plantenplagen - geïntegreerde bestrijding - gewasbescherming - plagenbestrijding - pseudococcidae - coccidae - ornamental plants - greenhouse horticulture - plant pests - integrated control - plant protection - pest control
    Als gevolg van het toenemend internationaal verkeer van plantmateriaal worden de risico’s op aantastingen door wol-, dop- en schildluizen groter. Daarbij komt dat breedwerkende middelen steeds minder gebruikt worden bij een verdere doorvoering van geïntegreerde bestrijding van gangbare plagen en door het verdwijnen van middelen. Hierdoor worden plagen die vroeger in het schema van breedwerkende middelen vanzelf werden meegenomen, opeens zichtbaar. Bestrijding van deze plagen vormt een bottleneck in de geïntegreerde bestrijding omdat tegen deze hardnekkige insecten momenteel alleen breedwerkende middelen voorhanden zijn. Daarnaast is het bestrijdingsresultaat van deze middelen vaak onvoldoende, waardoor ze frequent toegepast worden. PPO Glastuinbouw voerde een inventarisatie uit van de aanwezige soorten wol-, dop- en schildluizen en mate van schade en mogelijkheden van biologische en chemische bestrijdingsmethoden. Het project met de titel “Inventarisatie problemen met wol-, schild- en dopluizen” is gefinancierd door het Productschap Tuinbouw. Om na te gaan welke soorten problemen geven is een oproep gedaan in nieuwsbrieven van diverse LTO-gewasgroepen om wol-, dop- en schildluisproblemen te melden. Tevens werd verzocht materiaal voor opkweek en determinatie op te sturen naar het PPO. Naar aanleiding daarvan zijn meerdere inzendingen van materiaal binnengekomen. De wol-, dop- en schildluizen behoren tot de grote groep van plantensapzuigende insecten en zijn verwant aan wittevliegen en bladluizen. Kenmerkend is dat deze insecten zich veelal ‘te voet’ verplaatsen, want er komen geen gevleugelde vrouwtjes voor. Wel zijn de mannetjes vrijwel altijd gevleugeld. Verspreiding over grotere afstand vindt plaats door middel van wind, vogels, andere insecten, plantmateriaal en via kleding. Tekenen van aantasting zijn het glimmend worden van bladeren door honingdauw dat door wolluizen en dopluizen geproduceerd wordt, en groeiremming, bladverkleuring en misvorming. Veel van de in kassen voorkomende wol-, dop- en schildluizen tasten een breed scala aan siergewassen aan, waaronder potplanten (o.a. palmen, schefflera, croton, ficus, kalanchoë) en kuipplanten (camelia, oleander, eucalyptus, bougainville), maar ook snijbloemen zoals bijvoorbeeld roos en cymbidium. De meest voorkomende wolluis in Nederlandse kassen is de citruswolluis, Planococcus citri. Daarnaast komen onder andere de langstaartwolluis, Pseudococcus longispinus, en de kortstaartwolluis, Pseudococcus viburni, voor. Wat betreft schildluizen hadden de meeste inzendingen naar het PPO betrekking op schildluizen in cymbidium en de soorten die daar op voorkwamen waren Boisduval schildluis, Diaspis boisduvalii, en Oleander schildluis, Aspidiotus nerii. Een dopluis soort die tijdens de inventarisatie werd aangetroffen was de platte dopluis, Coccus hesperidum. Andere regelmatig voorkomende soorten in Nederlandse kassen zijn de halveboldopluis, Saissetia coffeae, en Saissetia oleae. Na een beschrijving van de levenswijze van wol-, dop en schildluizen, worden de belangrijkste soorten wol-, dop- en schildluizen apart besproken. Momenteel worden wol-, dop- en schildluizen veelvuldig biologisch bestreden in kantoortuinen en binnentuinen van zwembaden, dierentuinen en kassen bij botanische tuinen. De resultaten van biologische bestrijding zijn voor deze toepassingsgebieden over het algemeen goed, maar dit zijn nog geen productiekassen. Naast een literatuuronderzoek en een inventarisatie onder telers is onderzoek gedaan naar entomopathogene schimmels voor de bestrijding van dop- en schilluizen, chemische bestrijding van wolluis, chemische bestrijding van schildluis en biologische bestrijding van schildluis. De drie laatst genoemde onderzoeken worden in aparte delen van dit verslag beschreven. Voor een samenvatting van deze onderzoeken wordt verwezen naar het betreffende deel.
    Pathogenicity of Aschersonia spp. against whiteflies Bemisia argentifolii and Trialeurodes vaporariorum
    Meekes, E.T.M. ; Fransen, J.J. ; Lenteren, J.C. van - \ 2002
    Journal of Invertebrate Pathology 81 (2002). - ISSN 0022-2011 - p. 1 - 11.
    parasitoid encarsia-formosa - entomopathogenic fungi - biological-control - aleyrodis - survival - germination - greenhouses - tabaci
    Entomopathogenic fungi of the genus Aschersonia are specific for whitefly and scale insects. They can be used as biological control agents against silverleaf whitefly, Bemisia argentifolii and greenhouse whitefly, Trialeurodes vaporariorum. Forty-four isolates of Aschersonia spp. were tested for their ability to sporulate and germinate on semi-artificial media and to infect insect hosts. Seven isolates sporulated poorly (less than 1 x 10(7) conidia/dry weight) and 10 were not able to infect either of the whitefly species. Several isolates were able to produce capilliconidia. Infection level was not correlated with germination on water agar. After a selection based on spore production and infection, virulence of 31 isolates was evaluated on third instar nymphs of both whitefly species on poinsettia (Euphorbia pulcherrima). Whitefly infection levels varied between 2 and 70%, and infection percentages of B. argentifolii correlated with that of T vaporariorum. However, mortality was higher for T vaporariorum than for B. argentifolii, as a result of a higher 'mortality due to unknown causes.' Several isolates, among which unidentified species of Aschersonia originating from Thailand and Malaysia, A. aleyrodis from Colombia, and A. placenta from India showed high spore production on semi-artificial medium and high infection levels of both whitefly species. (C) 2002 Elsevier Science (USA). All rights reserved.
    Minder plannen dankzij ICT
    Fransen, H. - \ 2001
    In: Essaybundel kennisdisseminatie / Bloemen, M., Wageningen : Wageningen UR - p. 38 - 41.
    The CDTA-soluble pectic substances from soybean meal are composed of rhamnogalacturonan and xylogalacturonan but not homogalacturonan
    Huisman, M.M.H. ; Fransen, C.T.M. ; Kamerling, J.P. ; Vliegenthart, J.F.G. ; Schols, H.A. ; Voragen, A.G.J. - \ 2001
    Biopolymers 58 (2001). - ISSN 0006-3525 - p. 279 - 294.
    Structural characteristics of pectic substances extracted from soybean meal cell walls (water unextractable solids) with a chelating agent-containing buffer (0.05M 1,2-diaminocyclohexane-N,N,N,N-tetraacetic acid (CDTA) and 0.05M NH4-oxalate in 0.05M NaOAc buffer) were studied. The arabinogalactans present as side chains to the rhamnogalacturonan backbone were largely removed by enzymatic hydrolysis using endo-galactanase, exo-galactanase, endo-arabinanase, and arabinofuranosidase B. The remaining pectic backbone appeared to be resistant to enzymatic degradation by pectolytic enzymes. After partial acid hydrolysis of the isolated pectic backbone, one oligomeric and two polymeric populations were obtained by size-exclusion chromatography. Monosaccharide and linkage analyses, enzymatic degradation, and NMR spectroscopy of these populations showed that the pectic substances in the original extract contain both rhamnogalacturonan and xylogalacturonan regions, while homogalacturonan is absent.
    Entomopathogenic fungi against whiteflies : tritrophic interactions between Aschersonia species, Trialeurodes vaporariorum and Bemisia argentifolii, and glasshouse crops
    Meekes, E.T.M. - \ 2001
    Wageningen University. Promotor(en): J.C. van Lenteren; J.J. Fransen. - S.l. : S.n. - ISBN 9789058084439 - 181
    insectenplagen - aleyrodidae - entomopathogene schimmels - aschersonia - trialeurodes vaporariorum - bemisia argentifolii - gastheer parasiet relaties - biologische bestrijding - insect pests - aleyrodidae - trialeurodes vaporariorum - bemisia argentifolii - entomogenous fungi - aschersonia - host parasite relationships - biological control

    Many horticultural and agricultural crops are good host plants for the greenhouse whitefly, Trialeurodes vaporariorum, and the silverleaf whitefly, Bemisia argentifolii . Their damage to crops is manifold. When present in sufficient numbers they can cause leaf drop and inhibit fruit maturation. They are efficient vectors of economically important plant viruses. In addition, whiteflies produce honeydew, which soils and damages crops, and serves as a substrate for sooty moulds, thus reducing leaf photosynthesis and renders plants and fruits unsightly.

    As more environmentally responsible agricultural strategies are adopted, natural enemies of both whitefly species, will play an increasing role. Screening for natural enemies which are able to kill both pest insects quickly, without affecting other natural enemies, is an important line of research. Entomopathogenic fungi can meet these requirements and can therefore be a valuable asset to existing biological and chemical control measures. Our attention is directed towards the entomopathogenic fungi of the genus Aschersonia , which are specialised on whitefly and scale insects. Previous research indicated that Aschersonia aleyrodis is a promising whitefly control agent because of its tolerance to relative humidities as low as 50%, its long persistence on leaf surfaces and its compatibility with the parasitoid Encarsia formosa , but little is known about other species within the genus.

    This project consisted of two components: 1) to identify virulent isolates of Aschersonia spp. for the use against greenhouse and silverleaf whitefly, and 2) to study factors which influence the effectivity of entomopathogenic fungi, with special reference to host plant, humidity and their interaction.

    Forty-four isolates of Aschersonia spp. were tested for their ability to sporulate on semi-artificial media and to infect the insect hosts, both important criteria for selection of biocontrol agents. Seven isolates sporulated poorly (less than 5.10 7 conidia/culture) and ten were not able to infect either of the whitefly species. After a selection based on spore production and infection, virulence of 31 isolates was evaluated on third instar nymphs of both whitefly species on poinsettia ( Euphorbia pulcherrima ). Infection levels varied between 2 to 70%, and infection percentages of B. argentifolii correlated with that of T. vaporariorum . Several isolates, among which unidentified species of Aschersonia originating from Thailand and Malaysia, A. aleyrodis from Colombia, and A. placenta from India showed consistent results in their ability to infect both whitefly species. Of these isolates LD 50 and LT 50 values were compared to select the most virulent isolate for control of B. argentifolii and T. vaporariorum . Bioassays were carried out on intact poinsettia plants under glasshouse conditions and the dosage ranged from 14 to 1.4 x 10 5 conidia/cm 2 . On B. argentifolii LD 50 's varied between 1600 and 4800 conidia/cm 2 and LT 50 's between 4.6 - 8.7 days and on T. vaporariorum LD 50 's varied between 700 and 5300 conidia/cm 2 and LT 50 's between 4.5 and 9.9 days. For two isolates the optimum mortality did not occur at the highest dosage, which was also reflected in the speed of kill.

    To obtain better insight into the infection process of A. aleyrodis , A. placenta and an unidentified Aschersonia sp. scanning electron microscopy and bioassays were carried out. Conidia of Aschersonia spp. germinated readily on the cuticula of host insects as well as on water agar. On water agar A. placenta also produced capilliconidia. No germination was observed on poinsettia leaf surface, except on the leaf veins. On B. argentifolii the fungi formed large amounts of mucilage to attach themselves to the insect. Appressoria were formed before penetration, but also direct penetration was observed. This seemed not related to a specific site on the insect. For both whitefly species, first to third instar nymphs were most susceptible. If the population existed of fourth instar nymphs for more than 50%, infection levels dropped from 90 to 50%. Infected whitefly nymphs usually died in the stage following the treated stage. The fungus protruded from the insect via the margins or via the emergence folds of pupae, if humidity levels were high enough.

    Persistence of A. aleyrodis was studied on cucumber ( Cucumis sativus ), gerbera ( Gerbera jamesonii ) and poinsettia. Germination capacity and infectivity of conidia, which stayed on the different plants over a period of up to one month, were assessed. Average germination of conidia on the leaves was low (< 14%), whereas it was shown that most of the conidia transferred from the leaf to water agar were viable, even after having been present on the leaf surface for one month. Germination capacity was influenced by host plant species: it was highest on cucumber, followed by poinsettia and lowest on gerbera. On cucumber leaves, conidia stayed viable and were able to infect 90% of the whitefly nymphs, even at 31 days after spore application. On gerbera, germination capacity decreased considerably from 80% (day 0) to 40% (day 31). This was reflected in nymphal mortality, which declined from 75% to 40%. Despite the high germination capacity (60%) of conidia on poinsettia after a one month on the leaf surface, nymphal mortality decreased from 70% at the day of spore application to 10% after three days at leaf surface, and remained low throughout the monitoring period. The phyllosphere microflora, secondary plant metabolites and microclimate can play a role in these findings.

    Can phyllosphere humidity explain differences in insect mortality due to entomopathogenic fungi on different crops? This was tested for cucumber, gerbera, tomato ( Lycopersicon esculentum ) and poinsettia on which mycosis of T. vaporariorum and cotton aphid ( Aphis gossypii ) were determined in relation to host-plant climate. Phyllosphere humidity was estimated using climate and host-plant parameters. Hydrophobicity of the leaves and crop density were also taken into account. On cucumber, gerbera and tomato, the fungi A. aleyrodis and A. placenta caused over 90% mortality in whitefly, while another entomopathogenic fungus, Verticillium lecanii , caused 50% mortality. On poinsettia, whitefly mortality was significantly lower for all three fungi (ca. 20%). The phyllosphere of cucumber was more humid than that of the other crops. This cannot the lower whitefly mortality on poinsettia. The fact that poinsettia leaves were more hydrophobic than the other leaves may offer an explanation for the observed lower whitefly mortality, but chemical host-plant aspects may also play a role. Our results underline the importance of the first trophic level (plant) for entomopathogenic fungi in integrated pest management programs.

    The influence of relative humidity (RH) and host-plant species and their interaction on mycoses of T. vaporariorum by A. aleyrodis , A. placenta and V. lecanii was studied. Experiments conducted on poinsettia, gerbera and cucumber at 50% and 80% RH showed a clear host-plant effect. On cucumber and gerbera all fungi caused significantly higher mortality compared with the control and a higher humidity resulted in higher mortality by the fungus, whereas whitefly mortality on poinsettia remained low and was not significantly different from the control. Both Aschersonia spp. performed significantly better than V. lecanii . In following experiments an additional period of 0, 3, 6, 12, 24 or 48 hours of high RH was applied after treatment with A. aleyrodis and V. lecanii . Mortality caused by the fungus increased with a longer additional period of additional high RH and higher ambient humidity. However, the host-plant species effect exceeded the effect of ambient or additional high RH period; whitefly mortality was highest on cucumber and lowest on poinsettia. On poinsettia both fungi had hardly any effect on whitefly mortality, except after a 48 hrs additional high RH period. On gerbera and cucumber all fungal treatments were significantly different from the control and A. aleyrodis performed better than V. lecanii .

    The influence of cultivar differences on the efficacy of entomopathogenic fungi is also tested. The experiment was conducted in a glasshouse (semi-practice) using two gerbera cultivars, 'Bourgogne' and 'Bianca' with different plant structure and trichome density on the leaf: 'Bianca' having more and larger leaves and fewer trichomes/cm 2 than 'Bourgogne'. A. aleyrodis and V. lecanii were applied for the control of T. vaporariorum , in two concentrations, 10 6 and 10 7 conidia/ml. In 'Bianca', both fungi caused a whitefly mortality up to 80%. Whitefly mortality was higher for 10 7 than for 10 6 conidia/ml. In 'Bourgogne', V. lecanii caused a significantly lower mortality than A. aleyrodis . Although no cultivar differences in whitefly development time were found, other characteristics, like natural mortality and build-up of the whitefly population, seemed to differ. Differences in mortality levels in relation to cultivar (humidity, hit-probability) and whitefly characteristics may explain the differences between the efficacy of the fungal species.

    The host plant is the most important factor in this tritrophic system, exceeding the influence of ambient humidity. However, although entomopathogenic fungi are less successful in controlling whiteflies on poinsettia, these problems may be circumvented by use of formulation. Aschersonia spp. are highly virulent against whitefly pests, can cause natural epizootics in the field, can be grown on artificial media, are well adapted to survive in the canopy environment, and are compatible to/or even complementary with other natural enemies.

    Long-term disadvantages of selective root placement: root proliferation and shoot biomass of two perennial grass species in a two-year experiment
    Fransen, B. ; Kroon, H. de - \ 2001
    Journal of Ecology 89 (2001). - ISSN 0022-0477 - p. 711 - 722.
    1 The long-term benefits of root foraging in heterogeneous environments are unclear. The short duration of many previous studies may have overlooked the effects of patch depletion and root turnover, which may limit the long-term rewards of root foraging for perennial plants. 2 The benefits of root foraging were investigated for Holcus lanatus and Nardus stricta over two growing seasons. Shoot biomass of each species was measured in homogeneous nutrient-rich and nutrient-poor treatments and in a heterogeneous treatment consisting of a nutrient-rich and a nutrient-poor side, at a high and a low overall level of nutrient availability at the same patch contrast. Large initial differences in nitrate concentrations in the soil solution between the soil types disappeared so that, after several months, nitrate levels were low in all soil types. 3 In heterogeneous treatments, Holcus was able to proliferate roots in the nutrient-rich side compared with the nutrient-poor side, but only at the high overall level of nutrient availability. Nardus did not selectively place roots in the nutrient-rich side of the heterogeneous treatment at either nutrient level. 4 Root longevity, as determined by minirhizotron observations, revealed that roots of Holcus tended to be shorter lived than those of Nardus, and to live longer in nutrient-poor soils. 5 Initially, Holcus produced more shoot biomass in the heterogeneous treatments, at both overall levels of nutrient availability, than expected from values in the homogeneous treatments, but this advantage disappeared by the end of the first growing season and, after 2 years, shoot biomass in the heterogeneous treatments was much less than expected. At the high overall level of nutrient availability, Holcus shoot biomass was not significantly greater than that produced in the homogeneous nutrient-poor treatment. In contrast, shoot biomass of Nardus in the heterogeneous treatment was similar to the expected value, both after the first and second growing seasons. 6 For Holcus, fast root proliferation and presumably a high nutrient uptake resulted in increased shoot biomass in the short term, but this was then curtailed by rapid patch depletion and high losses due to a limited root life span. We discuss the implications for the long-term rewards of root proliferation in perennial species of heterogeneous environments.
    Soil nutrient heterogeneity alters competition between two perennial grass species
    Fransen, B. ; Kroon, H. de; Berendse, F. - \ 2001
    Ecology 82 (2001)99. - ISSN 0012-9658 - p. 2534 - 2546.
    Differences in root foraging behavior between species have been well documented, but the effects of these differences on belowground competitive ability are only beginning to be studied. Here we report the results of a competition experiment in homogeneous and heterogeneous soils between two species that differ in their ability to acquire nutrients from patchy environments. The perennial grasses Festuca rubra and Anthoxanthum odoratum have comparable growth rates, but results of previous studies with isolated plants designated the latter species as the more effective forager, probably due to its higher physiological plasticity (stronger increase in nutrient uptake rates per unit root mass in enriched nutrient patches). We introduced nutrient soil heterogeneity at two spatial scales. In a fine-grained heterogeneous treatment, the nutrient-rich patches were smaller and more concentrated than in a coarse-grained heterogeneous (checkerboard) treatment. Overall, the level of nutrient availability in these heterogeneous treatments was similar to a third treatment with homogeneous soils. The species Were grown in monocultures and mixtures in a standard replacement design during two growing seasons. In the homogeneous treatment, the relative competitive ability of F. rubra was higher than of A. odoratum, but F. rubra's advantage declined in the heterogeneous environments, and the relative competitive abilities became the same. Both species produced higher root densities in the richer patches of the fine-grained heterogeneous treatment, but not significantly so in the coarse-grained heterogeneous treatment, and these responses were the same for both species. The root activity of the species was assessed by determining the amount of strontium captured by a species at the end of the experiment, after injecting SrCl2 in the nutrient-rich patches and in equivalent locations in the homogeneous treatment. F. rubra acquired significantly more Sr in the mixtures in the homogeneous treatments, but in the coarse- and fine-grained heterogeneous treatment the nutrient acquisition abilities of the species were equal. These results suggest that a more effective root foraging behavior confers a higher competitive ability in heterogeneous environments. Moreover, the results on root-proliferation and nutrient-acquisition ability suggest that a higher physiological (rather than morphological) plasticity is critical in obtaining a long-term competitive advantage. Analyses of shoot size inequalities suggest that competitive interactions were size-symmetric in homogeneous soil and size-asymmetric in the heterogeneous treatments. However, in the long term, competition becomes more size-symmetric in the heterogeneous soils, consistent with the increasing importance of physiological plasticity.
    Biological control of whitefly on Gerbera: success or failure? : tritrophic interactions between Gerbera jamesonii, Trialeurodes vaporariorum and Encarsia formosa
    Sütterlin, S. - \ 2000
    Agricultural University. Promotor(en): J.C. van Lenteren; J.J. Fransen. - S.l. : S.n. - ISBN 9789058083241 - 177
    gerbera - insectenplagen - trialeurodes vaporariorum - biologische bestrijding - organismen ingezet bij biologische bestrijding - encarsia formosa - gastheer parasiet relaties - gerbera - insect pests - trialeurodes vaporariorum - biological control - biological control agents - encarsia formosa - host parasite relationships

    In this thesis fundamental and applied research is described that was initiated to develop biological control of whitefly with the parasitoid Encarsia formosa in the ornamental Gerbera jamesonii Hook (Campanulales: Compositae).

    To test the hypothesis that host plant architecture of G. jamesonii results in a different whitefly distribution pattern when compared with vegetables such as tomato and cucumber, we started studying whitefly dispersal behaviour and the choice of oviposition and feeding sites of the greenhouse whitefly within a plant. The behaviour of the herbivore was compared on two cultivars of G. jamesonii , differing in hairiness.

    The dispersal process of whiteflies was directed to the centre of the plant. This leads to adult and egg aggregation on young leaves on the hairy as well as on the less-hairy cultivar. Three parameters (development time, mortality and fecundity) to measure performance of T. vaporariorum were investigated, to determine a possible link with preference for certain leaves or cultivars by whitefly adults. Development duration of immatures is the same on leaves of different ages. Mortality of whiteflies is much lower and fecundity is higher on young Gerbera leaves. The dispersal and aggregation of whitefly adults between plants was investigated next. Whitefly populations were strongly aggregated on Gerbera , which seems typical for this whitefly species. Travel distance and dispersal speed were similar on very different crops such as Gerbera and tomato. Leaf selection behaviour and the resulting distribution of greenhouse whitefly on Gerbera was similar to that on vegetables. The first hypothesis that differences in host plant architecture result in different whitefly distributions is, thus, rejected.

    The second hypothesis that plant characteristics such as shape and leaf hairiness of G. jamesonii negatively influence the searching behaviour of the parasitoid E. formosa was tested next. Trichome density of Gerbera cultivars appeared to influence the walking behaviour (walking speed, walking activity and straightness of walkng path) and searching efficiency of E. formosa only slightly. Gerbera leaves of all age classes were found and searched by the parasitoid. Number of landings was the same on infested and uninfested Gerbera leaves; parasitoids were observed more often on the abaxial side of the leaves, where hosts are found normally. The foraging behaviour of E. formosa on leaves of a range of Gerbera cultivars is comparable. The searching efficiency of E. formosa on Gerbera is as good as on the vegetable tomato, so also the second hypothesis that plant characteristics negatively influence the searching behaviour of Encarsia on Gerbera , is rejected.

    The third hypothesis that plant architecture and leaf characteristics of G. jamesonii lead to failure of whitefly biological control on Gerbera was tested in glasshouses. Glasshouse studies are essential to validate the conclusions based on small population experiments and laboratory experiments. One central release of on average three parasitoids per plant, three weeks after whitefly introduction resulted in successful pest control in a small glasshouse of 60 m 2 . Sufficient control was not achieved in a larger glasshouse (300 m 2 ).

    Possible explanations for the failure of biological control in Gerbera were evaluated with a simulation model of G. jamesonii , T. vaporariorum and E. formosa . Surprisingly, and as a result of integrating all parameters for crop, pest, natural enemy and glasshouse temperature, we found that it is mainly the glasshouse temperature that determines success or failure of biological control in Gerbera .

    With an adjustment of the release strategy of parasitoids, the right choice of (partially) resistant Gerbera cultivars, and a slight increase of glasshouse temperature in early spring, biological control of T. vaporariorum on G. jamesonii will be successful.

    Persistence of the fungal whitefly pathogen, Aschersonia aleyrodis, on three different plant species
    Meekes, E.T.M. ; Voorst, S. van; Joosten, N.N. ; Fransen, J.J. ; Lenteren, J.C. van - \ 2000
    Mycological Research 104 (2000). - ISSN 0953-7562 - p. 1234 - 1240.
    Studies on the structure of a lithium-treated soybean pectin : characteristics of the fragments and determination of the carbohydrate substituents of galacturonic acid
    Fransen, C.T.M. ; Haseley, S.R. ; Huisman, M.M.H. ; Schols, H.A. ; Voragen, A.G.J. ; Kamerling, J.P. ; Vliegenthart, J.F.G. - \ 2000
    Carbohydrate Research : an international journal 328 (2000). - ISSN 0008-6215 - p. 539 - 547.
    Root morphological and physiological plasticity of perennial grass species and the exploitation of spatial and temporal heterogeneous nutrient patches
    Fransen, B. ; Blijjenberg, J. ; Kroon, H. de - \ 1999
    Plant and Soil 211 (1999)2. - ISSN 0032-079X - p. 179 - 189.
    Disentangling the effects of root foraging and inherent growth rate on plant biomass accumulation in heterogeneous environments : a modelling study
    Fransen, B. ; Kroon, H. de; Kovel, C.G.F. de; Bosch, F. van den - \ 1999
    Annals of Botany 84 (1999)3. - ISSN 0305-7364 - p. 305 - 311.
    Empirical evidence indicates that fast-growing species generally display a higher degree of selective root placement in heterogeneous environments than slow-growing species. Such root foraging is accomplished by root morphological responses, but since some morphological responses are simply the result of enhanced growth of the roots in the enriched patch it is difficult to separate the effects of root foraging and growth rate on the biomass accumulation of species in heterogeneous environments. Here a simple model is presented to disentangle these effects. Root foraging is incorporated as the selective allocation of root biomass per unit time to the nitrogen-rich patch. Growth rate differences among the model plants result from differences in nitrogen utilization efficiency. In the model, the degree of selective root placement can be varied independently of growth rate. The model shows that when plants are compared at a common point in time, selective root placement and growth rate interact positively with respect to the enhancement of plant biomass accumulation in heterogeneous compared to homogeneous environments. However, by evaluating the model at a common plant biomass, the main and interactive effects of growth rate are eliminated. These results suggest that growth rate by itself does not confer an advantage in terms of resource acquisition and biomass accumulation in heterogeneous environments. Only the selective placement of resource acquiring structures (such as roots) leads to such benefits. The essential differences between foraging and growth, as well as the consequences of differences in foraging ability and growth rate between species on competition for a limited resource, are discussed.
    Root foraging : the consequences for nutrient acquisition and competition in heterogeneous environments
    Fransen, B.L.L. - \ 1999
    Agricultural University. Promotor(en): F. Berendse; J.C.J.M. de Kroon. - S.l. : Fransen - ISBN 9789058081063 - 159
    grassen - planten - wortels - voedingsstoffenbeschikbaarheid - voedingsstoffenopname (planten) - rizosfeer - voedingsstoffen - biologische mededinging - concurrentie tussen planten - plasticiteit - interacties - grasses - plants - roots - nutrient availability - nutrient uptake - rhizosphere - nutrients - biological competition - plant competition - plasticity - interactions

    In natural habitats, the availability of essential mineral nutrients may vary widely from place to place and from time to time, at scales relevant to individual plants. Plants have developed root foraging mechanisms that enable them to acquire adequate amounts of nutrients in these heterogeneous environments. The ability of plants to proliferate roots in nutrient-rich patches has been shown frequently, but both the timing and the degree of root proliferation varied widely. Species from inherently nutrient-rich habitats in general display a higher relative increase in root density in nutrient-rich patches than species from inherently nutrient-poor habitats. This observation prompted the hypothesis that root foraging mechanisms differ between species from habitats of different nutrient availability.

    Overall, the results described in this thesis contradict this hypothesis. The higher degree of selective root placement displayed by species from more nutrient-rich habitats compared to species from more nutrient-poor habitats may result from differences in growth rate rather than from differences in root morphological plasticity. The results further indicate that selective root placement may confer an advantage in terms of nutrient acquisition in heterogeneous environments in the short-term, but in the long-term the increased root density may result in a lower rather than a higher biomass production in heterogeneous environments. However, root foraging abilities by which local nutrient patches are exploited may still be profitable when plants are grown in competition. The ability to rapidly exploit nutrient-rich patches due to root foraging characteristics seems to confer a competitive advantage in heterogeneous environments, even in the long-term.

    alpha-D-Glcp-(1-1)-ß-D-Galp-containing oligosaccharides, novel products from lactose by the action of ß-galactosidase
    Fransen, C.T.M. ; Laere, K.M.J. van; Wijk, A.A.C. van; Brüll, L.P. ; Dignum, M. ; Thomas-Oates, J.E. ; Haverkamp, J. ; Schols, H.A. ; Voragen, A.G.J. ; Kamerling, J.P. ; Vliegenthart, J.F.G. - \ 1998
    Carbohydrate Research : an international journal 314 (1998). - ISSN 0008-6215 - p. 101 - 114.
    A simple method to determine carbohydrate substituents of an uronic acid.
    Fransen, C.T.M. ; Huisman, M.M.H. ; Schols, H.A. ; Voragen, A.G.J. ; Kamerling, J.P. ; Vliegenthart, J.F.G. - \ 1998
    In: Proceedings of the International Carbohydrate Symposium, San Diego, USA (1998) AP075
    Alpha-D-Glcp-(1<->1)-beta-D-Galp containing oligosaccharides, a new class of oligosaccharides produced by beta-galactosidase form lactose as substrate.
    Fransen, C.T.M. ; Laere, K.M.J. van; Wijk, A.A.C. van; Brull, L.P. ; Dignum, M. ; Thomas-Oates, J. ; Haverkamp, J. ; Schols, H.A. ; Voragen, A.G.J. - \ 1998
    In: Proceedings of the International Carbohydrate Symposium, San Diego, USA (1998) AO028
    Root morphological plasticity and nutient aquisition of perennial grass species from habitats of different nutrient availability.
    Fransen, B. ; Kroon, H. de; Berendse, F. - \ 1998
    Oecologia 115 (1998). - ISSN 0029-8549 - p. 351 - 358.
    Abstract We studied the root foraging ability and its consequences for the nutrient acquisition of five grass species that differ in relative growth rate and that occur in habitats that differ widely in nutrient availability. Foraging responses were quantified, based on the performance of the plants in homogeneous and heterogeneous soil environments of the same overall nutrient availability. Although all species tended to produce a significantly higher root length density in a nutrient-rich patch, this response was significant only for the faster-growing species. The increased root length density resulted from small, though not significant, changes in root biomass and specific root length. The effectiveness of root proliferation was determined by quantifying the total amount of nutrients (N and P) accumulated by the plants over the course of the experiment. Plants acquired more N in a heterogeneous environment than in a homogeneous environment, although the total nutrient availability was the same. The ability to acquire nutrients (N or P) in the heterogeneous environment was not related to the ability of species to increase root length density in response to local nutrient enrichment. In contrast to other studies, our results suggest that the role of morphological plasticity of roots in acquiring patchily distributed resources is limited. Possible reasons for this discrepancy are discussed.
    Using image-analysis to quantify the horizontal vegetation pattern in two multi-species savanna grasslands.
    Fransen, B. ; Boer, M. de; Terlou, M. ; During, H. ; Dijkman, W. - \ 1998
    Plant Ecology 138 (1998). - ISSN 1385-0237 - p. 231 - 237.
    Structural Characterization of O-D-Glcp-(1?1)- -D-Galp-containing oligosaccharides; a new class of trans galacto-oligosaccharides.
    Fransen, C.T.M. ; Wijk, A.A.C. van; Laere, K.M.J. van; Voragen, A.G.J. ; Kamerling, J.P. ; Vliegenthart, J.F.G. - \ 1997
    In: International Symposium 'Non-digestible oligosaccharides: healthy food for the colon?', Wageningen, NL - p. 139 - 139.
    Effect of expander conditioning and/or pelleting of a diet containing tapioca, pea and soybean meal on the faecal digestibility for pigs.
    Poel, A.F.B. van der; Fransen, H.M.P. ; Bosch, M.W. - \ 1997
    Animal Feed Science and Technology 66 (1997). - ISSN 0377-8401 - p. 289 - 295.
    Schoolorganisatie-ontwikkeling in het perspectief van actief leren.
    Abbenhuis, R.A. ; Biemans, H.J.A. ; Jongmans, C.T. - \ 1997
    In: Studielandschap 2002, een leeromgeving met een goed (voor)uitzicht / Fransen, B.J.F., - p. 14 - 15.
    High levels of inter-ramet water translocation in two rhizomatous Carex species, as quantified by deuterium labelling.
    Kroon, H. de; Fransen, B. ; Rheenen, J.W.A. van; Dijk, A. van; Kreuler, R. - \ 1996
    Oecologia 106 (1996). - ISSN 0029-8549 - p. 73 - 84.
    Pathogenicity of entomopathogenic fungi of the genus Aschersonia against whitefly.
    Meekes, E.T.M. ; Fransen, J.J. ; Lenteren, J.C. van - \ 1996
    IOBC/WPRS Bulletin 19 (1996)1. - ISSN 0253-1100 - p. 103 - 106.
    Ziekten bij insekten
    Geest, L.P.S. van der; Beerling, E.A.M. ; Fransen, J.J. ; Smits, P.H. - \ 1995
    In: Insekten onderzoeken / Koomen, P., Ellis, W.N., van der Geest, L.P.S., - p. 175 - 186.
    Schimmel aschersonia alternatief voor bestrijding wittevlieg.
    Meekes, E.T.M. ; Fransen, J.J. - \ 1995
    Vakblad voor de Bloemisterij 20 (1995). - ISSN 0042-2223 - p. 35 - 35.
    The use of entomopathogenic fungi for the control of whiteflies.
    Meekes, E.T.M. ; Fransen, J.J. ; Lenteren, J.C. van - \ 1994
    Mededelingen van de Faculteit Landbouwwetenschappen, Rijksuniversiteit Gent 59 (1994). - p. 371 - 377.
    Survival of the parasitoid Encarsia formosa after treatment of parasitized greenhouse whitefly larvae with fungal spores of Aschersonia aleyrodis.
    Fransen, J.J. ; Lenteren, J.C. van - \ 1994
    Entomologia Experimentalis et Applicata 71 (1994). - ISSN 0013-8703 - p. 235 - 243.
    Host selection and survival of the parasitoid Encarsia formosa on greenhouse whitefly, Trialeurodes vaporariorum, in the presence of hosts infected with the fungus Aschersonia aleyrodis.
    Fransen, J.J. ; Lenteren, J.C. van - \ 1993
    Entomologia Experimentalis et Applicata 69 (1993). - ISSN 0013-8703 - p. 239 - 249.
    Luchtkwaliteit benzeen. Advies over het ontwerp-besluit luchtkwaliteit benzeen.
    Koeman, J.H. ; Brunekreef, B. ; Eijsackers, H.J.P. ; Fransen, J.T.J. ; Kleijs-Wijnnobel, C.J. ; Koningh, A.G.J. ; Kres, R.J. ; Notten, W.R.F. - \ 1990
    Unknown Publisher
    Dispersal of the greenhouse whitefly, Trialeurodes vaporariorum (Westwood), on the rosette plant gerbera.
    Sütterlin, S. ; Lenteren, J.C. van; Fransen, J.J. - \ 1990
    SROP/WPRS Bulletin XIII (1990)5. - p. 205 - 208.
    Verslag oriëntatie-missie naar de Sovjet Unie.
    Bor, W. van den; Fransen, B.J.F. - \ 1990
    Wageningen/Dronten : Vakgroep Agrarische Onderwijskunde/LU, STOAS - 16 p.
    List of pests in order of importance in relation to european countries.
    Fransen, J.J. - \ 1989
    IOBC/WPRS Bulletin 22 (1989)3. - ISSN 0253-1100 - p. 7 - 9.
    Volkstuinen, een aanzet tot detailonderzoek naar de particuliere verhuur
    Fransen, L. ; Schrandt, C.H. - \ 1987
    Wageningen : Instituut voor Cultuurtechniek en Waterhuishouding (Nota / Instituut voor Cultuurtechniek en Waterhuishouding no. 1790) - 33
    landgebruik - huur - volkstuinen - land use - rent - allotment gardens
    The differential mortality at various life stages of the greenhouse whitefly, Trialeurodes vaporariorum, by infection with the fungus Aschersonia aleyrodis.
    Fransen, J.J. ; Winkelman, K. ; Lenteren, J.C. van - \ 1987
    Journal of Invertebrate Pathology 50 (1987). - ISSN 0022-2011 - p. 158 - 165.
    Control of greenhouse whitefly, Trialeurodes vaporariorum, by the fungus Aschersonia aleyrodis.
    Fransen, J.J. - \ 1987
    In: Bull. OILB/SROP Budapest, Hungary - p. 57 - 61.
    Functional response and host preference of Encarsia formosa Gahan (Hym. Aphelinidae), a parasitoid of greenhouse whitefly T. vaporariorum Westwood (Hom. Aleyr).
    Fransen, J.J. ; Montfort, M.A.J. van - \ 1987
    Journal of Applied Entomology 103 (1987). - ISSN 0931-2048 - p. 55 - 69.
    Aschersonia aleyrodis as a microbial control agent of greenhouse whitefly
    Fransen, J.J. - \ 1987
    Agricultural University. Promotor(en): J.C. van Lenteren; J. Dekker. - S.l. : Fransen - 167
    aleyrodidae - insecten - plantenplagen - biologische bestrijding - schimmels - organismen ingezet bij biologische bestrijding - deuteromycotina - coelomycetes - glastuinbouw - aleyrodidae - insects - plant pests - biological control - fungi - biological control agents - deuteromycotina - coelomycetes - greenhouse horticulture
    Various aspects of the development of the entomopathogenic fungus Aschersoniaaleyrodis as a control agent of greenhouse whitefly, Trialeurodesvaporariorum , were investigated. For control of greenhouse whitefly in tomato crops the parasitoid Encarsiaformosa has been successful, but in cucumber crops a successful suppression of the whitefly population is often not achieved. Therefore, an additional selective control method is needed. The attention was focused on the fungal pathogen Aschersoniaaleyrodis (Chapter 1).

    The spores of A. aleyrodis germinated on the integument of whitefly larvae. Penetration of the cuticle took place after formation of an appressorium. The haemolymph and insect tissues were colonized by the fungus and the insect changed in colour from transparent yellow green to clear or opaque orange. Under favourable conditions the mycelium protruded from the insect and orange-coloured spore masses were produced in a mucilaginous layer (Chapter 2).

    Information on the susceptibility of greenhouse whitefly at the various life stages is of importance for application of A. aleyrodis . Eggs of the host did not become infected. First instar, second instar and third instar larvae were highly susceptible to infection. Fourth instar larvae were susceptible to a lesser extent. When these larvae developed into the so-called prepupal and pupal stage the cuticle changed and the whitefly became more resistant. Generally, adults did not become infected (Chapter 3).

    Dose-mortality responses were determined for the first, second, third and fourth instar larvae. Several experiments over time were carried out which gave consistent results. The dosage of spores on leaves needed to obtain 50% mortality (LC50) of first, second and third instar larvae was 19.53 spores/mm 2, 21.03 spores/mm2 and 33.81 spores/mm 2, respectively. This represents a dose of about 0.77 spores per first instar larva, 1.44 per second instar larva and 4.39 spores per third instar larvae. The LC95 values, expressed as number of spores per amount sprayed, were 1.98 X 10 7spores/2ml for first instar larvae, 2.34 x 10 7spores/2ml for second instar larvae and 3.27 X 10 7spores/2ml for third instar larvae. The LC95 for fourth instar larvae was outside the dosage range tested. The LC50 varied with the age of the fourth instar larvae, from 6.0 x 10 6spores/2ml to 2.6 x 10 8spores/2ml in two different bioassays. The period before 50% of the larvae showed signs of infection (orange colouration) (LT50) at 20°C, was 11.8 days for first instar larvae, 9.5 days for second instar larvae and 7.0 days for third instar larvae, after application of 5.0 x 107 spores in 2 ml. The LT25 for fourth instar larvae was 5.6 days (Chapter 4).

    Another bioassay method was tested using cucumber leaf discs (6.5 cm, diameter). The presence of free water on the leaf surface enhanced the infection to such a degree that 77 to 90% of the larvae became infected after application of 1.0 x 10 6spores in 2 ml per leaf disc. No LC50 values could be derived. After exposure of larvae to dosages of 5.0 x 10 7and 1.0 x 10 8spores in 2 ml a delay in the development of infection was noticed. After treatment of fourth instar larvae the final percentage infection was lower at the higher dosages than at the lower dosages. This was different from the linear relationship found in previous bioassays on plants. on water agar the spores of A. aleyrodis showed reduced germination at high densities (3100 spores/mm2). This density-dependent effect of the spores on the germination was apparently also present when leaf discs were used under conditions of high humidity and free water on the leaf surface. This may indicate the presence of a self-inhibitor (Chapter 5).

    Impressions of cucumber leaves treated with A. aleyrodis spore suspension on water agar showed that only a low percentage of the spores (4.5%) germinated on the leaf surface. However, the ungerminated spores remained viable and infective for a long time. Spores from leaves treated 43 days before showed 78% germination after incubation on water agar for 24 hr. whitefly treated in the egg stage became infected when young larvae contacted spores on the leaf surface after hatching. Nearly all young larvae (96%) contacting spores present on the leaf surface for about 22 days became infected (Chapter 6).

    When aiming to apply A. aleyrodis in a glasshouse environment knowledge on the influence of temperature and relative humidity (RH) is wanted. over 90% of the A. aleyrodis spores germinated within 48 hr on water agar in the temperature range of 15 to 28°C. Larvae were infected at 15, 20, 25 and 30°C, with the most rapid development at 30°C, (LT50: 3.3 days), though the final mortality rates of whitefly at the different temperatures were the same. Spores on cellophane sheets were exposed to various relative humidities. Germination was fastest at 100% RH and 20°C (78% within 24 hr), but after 168 hr 88% of the spores germinated at 93.9% RH. In experiments using cucumber plants it was found that successful infection of the larvae occurred at a RH of 50% and 20°C A period of 100% RH for 24 hr enhanced the development of infection (LT50: 7.1 days). After exposure of the plants bearing treated larvae to 0, 3, 6, 12 or 24 hr 100% RH a linear relationship between these periods of high humidity and the LT50 values was not observed. The LT50 value amounted to 8.9, 8.6, 10.4 and 10.1 days for periods of 0, 3, 6 and 12 hr high RH, respectively. It is suggested that germinating spores are in a vulnerable phase after the periods of 6 and 12 hr at 100% RH, and are then highly susceptible to the decrease in RH from 100% to 50% (Chapter 7).

    Serial in vitro passages of the fungus influenced the rate in which signs of infection became apparent. one in vivo passage of A.aleyrodis on greenhouse whitefly did not influence the infection rate but this needs further investigation (Chapter 7).

    The interaction between A. aleyrodis and the parasitoid Encarsiaformosa was studied in relation to the introduction of both natural enemies for control of whitefly (Chapters 8 and 9). From behavioural observations it could be concluded that the parasitoid was able to distinguish infected hosts from noninfected hosts if the fungus is present in the haemolymph of the host. Infected larvae were rejected for oviposition after the ovipositor penetrated the host. From four days onwards after inoculation of the spores the parasitoid could detect the fungus in the host. By distinguishing between infected and noninfected hosts the parasitoid is able to complement the fungal pathogen. E. formosa was able to transmit A. aleyrodis from infected hosts to noninfected hosts by the contaminated ovipositor. The transmission of the fungus was restricted to one or two healthy hosts (Chapter 8).
    whitefly larvae parasitized by E. formosa more than three days before were not susceptible to infection by the fungus. Nonparasitized larvae, however, were still infected by the fungus. The regulation of this phenomenon of reduced susceptibility in parasitized larvae is yet unknown. It may be related to the hatching of the parasitoid larva from the egg in the host (Chapter 9).

    From the presented results of the experiments it can be concluded that A. aleyrodis shows promise as a microbial control agent of greenhouse whitefly in glasshouses (Chapter 10). Further research should be concentrated on the development of mass production, formulation of a product and application strategies.

    The survival of spores of Aschersonia aleyrodis, an entomopathogenic fungus of greenhouse whitefly, Trialeurodes vaporariorum.
    Fransen, J.J. - \ 1986
    In: Fundamental and applied aspects of invertebrate pathology, R.A. Samson, J.M. Vlak, D. Peters (eds.). Proc. 4th Int. Coll. Invertebrate Pathology (1986) 226
    System models in epizootiology and insect control.
    Rabbinge, R. ; Fransen, J.J. ; Soest., R. van - \ 1986
    In: Fundamental and applied aspects of invertebrate pathology, R.A. Samson, J.M. Vlak, D. Peters (eds.). Proc. 4th Int. Coll. Invertebrate Pathology - p. 584 - 585.
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