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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    Nieuwe mogelijkheden voor de bestrijding van trips in de sierteelt onder glas
    Messelink, Gerben J. ; Leman, Ada ; Holstein-Saj, Renata van; Tol, Rob van; Vijverberg, Roland ; Elfferich, Caroline ; Catalá Senent, Laura ; Huang, Tze-Yi ; Shresta, Kriti ; Kruidhof, Marjolein - \ 2019
    Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Rapport / Stichting Wageningen Research, Wageningen Plant Research, Business unit Glastuinbouw GTB-895) - 90
    Western flower thrips, Frankliniella occidentalis, is a major pest species in greenhouse ornamental crops. They cause damage to leaves and flowers and can transmit viruses. Effective control requires a systems approach where measures that increase plant resilience are combined with biological control, mass trapping and (bio) pesticides. Het aim of this project with the title “Master plan thrips management in greenhouse ornamental crops” was to develop enhanced thrips control measures through 1) increased plant resilience with fungal endophytes, 2) preventive releases of natural enemies (standing army) and 3) manipulation of thrips behaviour. This report presents the results of this project that was done in the period 2015-2019.
    Identifying and Engineering Genes for Parthenogenesis in Plants
    Vijverberg, C.A. ; Ozias-Akins, Peggy ; Schranz, M.E. - \ 2019
    Frontiers in Plant Science 10 (2019). - ISSN 1664-462X
    Parthenogenesis is the spontaneous development of an embryo from an unfertilized egg cell. It naturally occurs in a variety of plant and animal species. In plants, parthenogenesis usually is found in combination with apomeiosis (the omission of meiosis) and pseudogamous or autonomous (with or without central cell fertilization) endosperm formation, together known as apomixis (clonal seed production). The initiation of embryogenesis in vivo and in vitro has high potential in plant breeding methods, particularly for the instant production of homozygous lines from haploid gametes [doubled haploids (DHs)], the maintenance of vigorous F1-hybrids through clonal seed production after combining it with apomeiosis, reverse breeding approaches, and for linking diploid and polyploid gene pools. Because of this large interest, efforts to identify gene(s) for parthenogenesis from natural apomicts have been undertaken by using map-based cloning strategies and comparative gene expression studies. In addition, engineering parthenogenesis in sexual model species has been investigated via mutagenesis and gain-of-function strategies. These efforts have started to pay off, particularly by the isolation of the PsASGR-BabyBoom-Like from apomictic Pennisetum, a gene proven to be transferable to and functional in sexual pearl millet, rice, and maize. This review aims to summarize the current knowledge on parthenogenesis, the possible gene candidates also outside the grasses, and the use of these genes in plant breeding protocols. It shows that parthenogenesis is able to inherit and function independently from apomeiosis and endosperm formation, is expressed and active in the egg cell, and can induce embryogenesis in polyploid, diploid as well as haploid egg cells in plants. It also shows the importance of genes involved in the suppression of transcription and modifications thereof at one hand, and in embryogenesis for which transcription is allowed or artificially overexpressed on the other, in parthenogenetic reproduction. Finally, it emphasizes the importance of functional endosperm to allow for successful embryo growth and viable seed production.
    Plaagbestrijding met omnivore roofwantsen : effecten van omnivore roofwantsen op plagen in gerbera, tomaat en roos en de risico’s op bloem- en vruchtschade
    Messelink, Gerben J. ; Vijverberg, Roland ; Elfferich, Caroline ; Koorneef, Marijke ; Driss, Laetitia ; Moeratidis, Angelos ; Woelke, Joop ; Català Senent, Laura ; Leman, Ada - \ 2019
    Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Wageningen University & Research, BU Glastuinbouw rapport WPR-850) - 90
    Omnivore roofwantsen van de familie Miridae hebben de bijzondere eigenschap dat ze zowel van plantmateriaal als van prooien kunnen leven. Dit brede voedselmenu heeft enorme voordelen voor de biologische bestrijding, omdat ze daardoor verschillende plaagsoorten kunnen bestrijden en tegelijkertijd preventief ingezet kunnen worden doordat ze zich voeden met plantsappen en/of alternatief voedsel. Dit voordeel van plantenvoeding is tegelijkertijd een nadeel, omdat de wantsen ook schade kunnen geven aan bloemen en vruchten. In dit project is de potentie voor plaagbestrijding met een aantal soorten omnivore roofwantsen onderzocht in gerbera, roos en tomaat. De plaagbestrijding was gericht op wittevlieg (gerbera en tomaat), Echinothrips (roos en gerbera), Tuta absoluta (tomaat), Turkse mot (gerbera en tomaat) en Nesidiocoris tenuis (tomaat). Daarnaast hebben we gekeken naar de schade die ze kunnen veroorzaken in gerbera en tomaat en is gekeken naar methoden om vestiging te verbeteren.---Omnivorous predators of the Miridae family feed both on plant and prey. This ability is a huge advantage forestablishment into crops when pests are absent or scarce, but at the same time a risk when through plantfeeding fruit and flowers get damaged. In this project we evaluated the potential for pest control with miridpredators in gerbera, rose and tomato crops. Pest control was assessed for whiteflies (gerbera and tomato),Echinothrips (gerbera and rose), Tuta absoluta (tomato), The Tomato Looper (gerbera and tomato) andNesidiocoris tenuis (tomato). In gerbera and tomato, not only pest control, but also the level of crop damagethese mirids can cause was assessed. Finally, methods to enhance establishment were evaluated.
    Nieuwe methoden voor bestrijding van bodemplagen in de glastuinbouw : Deel 3: Ontwikkeling ‘attract- en kill’ strategie voor rouwmuggen (Sciaridae) en oevervliegen (Ephydridae)
    Kruidhof, Marjolein ; Woelke, Joop ; Vijverberg, Ruben ; Català-Senent, Laura ; Vijverberg, Roland - \ 2018
    Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Wageningen University & Research, BU Glastuinbouw rapport WPR-787) - 57
    In this report the research into the development of an attract- and kill strategy for sciarid flies (Sciaridae) and shore flies (Ephydridae) is described. First it has been evaluated which substrate compositions were the most and least attractive to sciarid fly females. Subsequently, an attractive substrate has been developed, which in combination with a yellow sticky trap could attract twice as many sciarid flies in a commercial greenhouse as a yellow sticky trap alone, and in cages could reduce the number of sciarid flies that developed in the growth substrate of viola plants to 50%. Moreover, the predatory beetle Dalotia (previously Atheta) coriaria was also attracted to this substrate. Shore flies did not react to odours of substrate or algae. However, in a greenhouse compartment a spontaneous contamination of shore flies with an entomopathogenic fungus was discovered. The effectiveness of this Beauveria bassiana isolate against shore flies has been compared with commercial entomopathogenic fungi, and has been subsequently used for the development of an attract- and kill method. Experiments have shown that shore flies can transfer this deadly fungus from containers with algae to which the fungus has been added, to other algae spots where shore flies develop.
    Biologische bestrijding van wol- en schildluis in de sierteelt onder glas
    Kruidhof, Marjolein ; Leman, Ada ; Catalá-Senent, Laura ; Vijverberg, Roland ; Messelink, Gerben - \ 2018
    Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Wageningen Plant Research rapport WPR-785) - 58
    Dit project had als doel om de biologische bestrijding van wol-en schild luis in roos en snijcymbidium te verbeteren met nieuwe inzetstrategieën van bestaande bestrijders en door evaluatie van complementaire nieuwe bestrijders. De zoek-efficiëntie van twee soorten sluipwespen van citruswolluis kon worden verbeterd door de sluipwespen voor het uitzetten in de kas te trainen op de geur van wolluis-geïnfesteerde rozenplanten. De roofkever Rhyzobius lophanthae kwam als beste bestrijder van Diaspis boisduvalii schildluis naar voren in een vergelijkende kooiproef met Cymbidium. Kasproeven wezen uit dat deze roofkevertjes weliswaar snel en gemakkelijk nieuwe schildluishaarden konden lokaliseren, maar dat het aantal volwassen R. lophanthae dat in de schildluishaard bleef relatief laag was. Verder werden kleine haarden over het algemeen minder goed opgeruimd dan grotere haarden. Bijvoeren met Ephestia eitjes kon de schildluisbestrijding in kleine schildluishaarden enigszins verbeteren. In labproeven kon de levensduur van volwassen R. lophanthae in de afwezigheid van schildluis met verschillende soorten alternatief voedsel worden verlengd. Hoewel R. lophanthae een belangrijke bijdrage leverde aan de schildluisbestrijding, konden zich ondanks het regelmatige uitzetten toch steeds nieuwe schildluishaarden vormen. Additionele bestrijders zijn nodig om beginnende schildluishaarden aan te pakken en de werking van R. lophanthae te versterken. Oorwormen en roofmijten bleken hiervoor niet geschikt.---The objective of this project was to improve the control of mealybugs and scale-insects in rose and cut cymbidium with new release strategies of existing natural enemies and through the evaluation of complementary new natural enemies. The searching efficacy of two parasitoid species of citrus-mealybugs could be improved by training them with the odour of mealybug-infested rose plants. In a comparative cage experiment with Cymbidium plants, the predatory beetle Rhyzobius lophanthae gave the best control of Diaspis boisduvalii scales. Additional greenhouse experiments showed that these beetles could easily find new scale-infestations, but that the number of adult R. lophanthae remaining in the infected areas was relatively low. Moreover, small scaleinfestations were less well controlled than larger scale-infestations. Adding Ephestia eggs as additional food could somewhat improve the control of small scale-infestations. Additional laboratory experiments showed that several alternative food sources were suitable to enhance the survival of R. lophanthae in the absence of scales. Even thus R. lophanthae could give an important contribution to scale control, new infestations could establish in spite of its repeated release. Additional control agents are needed to control beginning scale infestations and complement the effect of R. lophanthae. Earwigs and predatory mites were not suitable in this regard.
    Stomach contents and stable isotopes confirm ontogenetic diet shifts of Nile perch, Lates niloticus, in southern Lake Victoria
    Cornelissen, I.J.M. ; Vijverberg, J. ; Beld, A.M. van den; Helmsing, N.R. ; Verreth, J.A.J. ; Nagelkerke, L.A.J. - \ 2018
    Journal of Great Lakes Research 44 (2018)6. - ISSN 0380-1330 - p. 1264 - 1272.
    Caridina shrimp - Fish-food relationships - Haplochromine cichlids - Rastrineobola argentea - Tropical lake

    Nile perch (Lates niloticus), a main target for Lake Victoria's fisheries, shifts its diet from invertebrates to fish during its ontogeny. We combined stomach contents with stable isotopes to study these diet shifts in Mwanza Gulf, southern Lake Victoria. During four seasons between 2009 and 2011 we collected and analysed 6697 stomachs and 516 stable isotope samples of Nile perch. Caridina shrimp and haplochromine cichlids were the major food items in Nile perch of 5–40 cm. Based on stomach contents, the shift of dominance of Caridina towards haplochromines in the diet varied from 6.7 cm length in the southern part of the gulf, to >20 cm in the northern part, possibly related to the higher abundance of Caridina in the north. In general isotope-based and stomach-content-based estimates of Nile perch diets agreed. We observed only two discrepancies: in Nile perch >20 cm, the isotope-based estimates of the contribution of haplochromines to the diet were much lower than based on stomach contents and the contribution of juvenile Nile perch to the diet were much higher in the isotope-based estimates than in the stomach based-based estimates. This discrepancy may be explained by e.g. different timespan-coverages between isotopes and stomach contents, by movements of Nile perch between the Gulf and the rest of Lake Victoria, or by the overlapping isotopic profiles of haplochromines and juvenile Nile perch. With the recent recovery of haplochromines in Lake Victoria, Nile perch appears to rely more on this prey again, as it did in the 1980s.

    Nieuwe methoden voor bestrijding van bodemplagen in de glastuinbouw. Deel 1: Biologie en bestrijding van Lyprauta sp. /
    Kruidhof, Marjolein ; Woelke, Joop ; Vijverberg, Ruben ; Català-Senent, Laura ; Vijverberg, Roland - \ 2018
    Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Wageningen University & Research, BU Glastuinbouw rapport WPR-784) - 54
    In de teelt van Phalaenopsis orchideeën wordt belangrijke schade veroorzaakt door zogenaamde ‘potwormen’, feitelijk muggenlarven van de familie Keroplatidae (langhoornmuggen). Deze larven, welke zich in het substraat bevinden, prederen in eerste instantie op bodemorganismen. Ze veroorzaken echter ook vraatschade aan wortelpunten, wat leidt tot een algehele groeivertraging. Zelfs bij lage aantallen langhoornmug larven - meestal zit er maar één larve in een pot - wordt de schadedrempel al overschreden door het relatief lage aantal wortels van Phalaenopsis. In dit rapport is het onderzoek beschreven naar a) de biologie van langhoornmuggen, met name naar Lyprauta cambria, en b) verschillende manieren om L. cambria te bestrijden, en/of ervoor te zorgen dat de larven minder schade berokkenen aan de wortelpunten van Phalaenopsis---In the cultivation of Phalaenopsis orchids important damage is caused by so-called ‘potworms’, which in reality are the larvae of the Keroplatidae family (fungus gnats). These larvae live in the substrate, and primarily predate on soil-dwelling organisms. However, they also cause feeding damage to the root tips, leading to a reduction in overall plant growth. Even at low Keroplatidae density – mostly only a single larva per pot is present – the damage threshold is often exceeded in Phalaenopsis because of its relatively low number of roots. In this report research addressing a) the biology of Keroplatidae larvae, with special focus on Lyprauta cambria, and b) different ways to control L. cambria, and/or reduce the damage that the larvae cause to the root tips of Phalaenopsis is described
    Heterogeneity in food-web interactions of fish in the Mwanza Gulf, Lake Victoria : a quantitative stable isotope study
    Cornelissen, Ilse J.M. ; Vijverberg, J. ; Beld, A.M. ; Helmsing, N.R. ; Verreth, J.A.J. ; Nagelkerke, L.A.J. - \ 2018
    Hydrobiologia 805 (2018)1. - ISSN 0018-8158 - p. 113 - 130.
    Haplochromines - Nile perch - Population-level metrics - Trophic level - Tropical lake
    Stable isotope analyses and derived population-level metrics were used to quantitatively analyse spatial and seasonal heterogeneity in the fish trophic dynamics in relation to environmental variables in Mwanza Gulf, Lake Victoria (Tanzania). The fish community in Lake Victoria, including the top predator Nile perch, is generally omnivorous with a heavy reliance on invertebrates. This is in contrast to findings based on stomach content analyses of Nile perch, which showed a stronger reliance on fish. We tested two hypotheses: (1) during the rainy seasons multiple carbon sources influence the food-web structure inside the Gulf, leading to increased carbon ranges and trophic diversity. (2) During dry periods, the food-web structure mainly relies on pelagic primary production, reducing carbon ranges and trophic diversity. Carbon sources indeed varied seasonally and spatially, affecting the fish community at the highest trophic levels. With the onset of rains, carbon sources became spatially highly differentiated with enriched δ13C values of fish in shallow water inside the Gulf and depleted δ13C values in open waters. Metrics associated with niche size correlated significantly with seasonally varying environmental variables, while δ13C ranges correlated with spatially varying environmental variables.
    Geïntegreerde bestrijding van plagen in de sierteelt onder glas : een systeembenadering met preventieve biologische bestrijding als basis
    Messelink, G.J. ; Leman, A. ; Ghasemzadeh Dizaji, Somaiyeh ; Bloemhard, C.M.J. ; Holstein, R. van; Vijverberg, Roland ; Muñoz-Cárdenos, Karen - \ 2016
    Bleiswijk : WageningenUR Glastuinbouw (Rapport GTB 1420) - 98
    siergewassen - glastuinbouw - kasgewassen - rozen - chrysanten - alstroemeria - biologische bestrijding - organismen ingezet bij biologische bestrijding - geïntegreerde bestrijding - geïntegreerde plagenbestrijding - thrips - neoseiulus cucumeris - trialeurodes vaporariorum - aleyrodes - bemisia tabaci - amblyseius swirskii - euseius - iphiseius - roofmijten - orius - cryptolaemus montrouzieri - anagyrus pseudococci - planococcus citri - ornamental crops - greenhouse horticulture - greenhouse crops - roses - chrysanthemums - alstroemeria - biological control - biological control agents - integrated control - integrated pest management - thrips - neoseiulus cucumeris - trialeurodes vaporariorum - aleyrodes - bemisia tabaci - amblyseius swirskii - euseius - iphiseius - predatory mites - orius - cryptolaemus montrouzieri - anagyrus pseudococci - planococcus citri
    The control of greenhouse pests in ornamental crops is getting more difficult because of the decreasing number of available pesticides. Alternative methods of pest control, based on biopesticides and natural enemies is promising, but not yet robust and reliable enough. In this project we developed and evaluated several methods to enhance the biological control of western flower thrips, Echinothrips americanus, whiteflies and mealybugs. Most studies were focused on preventive control measures that promote the establishment and efficacy of natural enemies by using top layers, alternative food, artificial domatia and a banker plant system. Furthermore we studied the interaction between parasitoids and predatory beetles for curative control of mealybugs. Finally, a number of (bio)pesticides was evaluated for their potential use as a correction tool against western flower thrips.
    Identification of conserved miRNAs in Petunia axillaris and P. inflata young flower buds and their verification in the Petunia genome sequence : Supplementary note 9 of Insights into the evolution of the Solanaceae from the parental genomes of Petunia hybrida
    Vijverberg, C.A. ; Agostino, Nunzio D'; Gerats, Tom - \ 2016
    Nature Plants 2 (2016)6. - ISSN 2055-026X
    Ontwikkeling push-pull strategie voor bestrijding rouwmuggen
    Kruidhof, Marjolein ; Vijverberg, Ruben - \ 2016
    Push-pull strategie kan helpen bij bestrijden kieskeurige rouwmuggen
    Kruidhof, Marjolein ; Vijverberg, Ruben - \ 2016
    plant protection - pest control - animal behaviour - insect attractants - experimental design - culicidae - greenhouse horticulture
    Alternatieven voor neonicotinoïden in de sierteelt onder glas : bestrijding van tabakswittevlieg en bladluis in kuipplanten en perkgoed
    Messelink, Gerben ; Vijverberg, Roland ; Bloemhard, Chantal ; Leman, Ada - \ 2016
    Bleiswijk : Wageningen UR Glastuinbouw (Rapport GTB 1418) - 42
    tuinplanten - containerplanten - insectenplagen - bemisia tabaci - aphididae - kasgewassen - glastuinbouw - biologische bestrijding - insecticiden - lecanicillium muscarium - entomopathogene schimmels - roofinsecten - bedding plants - container grown plants - insect pests - bemisia tabaci - aphididae - greenhouse crops - greenhouse horticulture - biological control - insecticides - lecanicillium muscarium - entomogenous fungi - predatory insects
    The control of phloem feeding insects such as aphids, whiteflies, cicadas, mealybugs, scales and plant feeding bugs in greenhouse crops still largely depends on the use of neonicotinoids. However, the increased found negative effects on the environment will soon results in a total ban on the use of these pesticides. In this project we summarized the possible alternative control measures with pesticides and biological control agents. Furthermore, a number of preventive and curative control measures was evaluated for the control of aphids in bedding plants and the tobacco whitefly in container plants, with Calibrachoa and Mandevilla as model plants. An endophytic application of an isolate of the entomopathogenic fungus Lecanicillium gave a clear trend of 25% reduced population growth of aphids on Calibrachoa. Curative control of aphids with lacewings was not effective. Mullein plants enhanced tobacco whitefly control by the predatory bug Macrolophus pygmaeus in Mandevilla and increased predator survival and reproduction. Among the tested alternative control measures, we found 5 products that controlled tobacco whiteflies effectively in Mandevilla.
    Insight into the evolution of the Solanaceae from the parental genomes of Petunia hybrida
    Bombarely, Aureliano ; Moser, Michel ; Amrad, Avichai ; Bao, Manzhu ; Bapaume, Laure ; Barry, Cornelius S. ; Bliek, Mattijs ; Boersma, Maaike R. ; Borghi, Lorenzo ; Bruggmann, Rémy ; Bucher, Marcel ; Agostino, Nunzio D'; Davies, Kevin ; Druege, Uwe ; Dudareva, Natalia ; Egea-Cortines, Marcos ; Delledonne, Massimo ; Fernandez-Pozo, Noe ; Franken, Philipp ; Grandont, Laurie ; Heslop-Harrison, J.S. ; Hintzsche, Jennifer ; Johns, Mitrick ; Koes, Ronald ; Lv, Xiaodan ; Lyons, Eric ; Malla, Diwa ; Martinoia, Enrico ; Mattson, Neil S. ; Morel, Patrice ; Mueller, Lukas A. ; Muhlemann, Joëlle ; Nouri, Eva ; Passeri, Valentina ; Pezzotti, Mario ; Qi, Qinzhou ; Reinhardt, Didier ; Rich, Melanie ; Richert-Pöggeler, Katja R. ; Robbins, Tim P. ; Schatz, Michael C. ; Schranz, Eric ; Schuurink, Robert C. ; Schwarzacher, Trude ; Spelt, Kees ; Tang, Haibao ; Urbanus, Susan L. ; Vandenbussche, Michiel ; Vijverberg, Kitty ; Villarino, Gonzalo H. ; Warner, Ryan M. ; Weiss, Julia ; Yue, Zhen ; Zethof, Jan ; Quattrocchio, Francesca ; Sims, Thomas L. ; Kuhlemeier, Cris - \ 2016
    Nature Plants 2 (2016). - ISSN 2055-026X

    Petunia hybrida is a popular bedding plant that has a long history as a genetic model system. We report the whole-genome sequencing and assembly of inbred derivatives of its two wild parents, P. axillaris N and P. inflata S6. The assemblies include 91.3% and 90.2% coverage of their diploid genomes (1.4 Gb; 2n = 14) containing 32,928 and 36,697 protein-coding genes, respectively. The genomes reveal that the Petunia lineage has experienced at least two rounds of hexaploidization: the older gamma event, which is shared with most Eudicots, and a more recent Solanaceae event that is shared with tomato and other solanaceous species. Transcription factors involved in the shift from bee to moth pollination reside in particularly dynamic regions of the genome, which may have been key to the remarkable diversity of floral colour patterns and pollination systems. The high-quality genome sequences will enhance the value of Petunia as a model system for research on unique biological phenomena such as small RNAs, symbiosis, self-incompatibility and circadian rhythms.

    Biological control of mealybugs with lacewing larvae is affected by the presence and type of supplemental prey
    Messelink, Gerben J. ; Vijverberg, Roland ; Leman, Ada ; Janssen, Arne - \ 2016
    BioControl 61 (2016)5. - ISSN 1386-6141 - p. 555 - 565.
    Biological control - Chrysoperla lucasina - Mixed diets - Planococcus citri

    The diversity of prey and food sources in crops has a major effect on biological pest control by generalist predators. In this study, we tested if and how supplemental prey or food affects the control of the citrus mealybug Planococcus citri (Risso) by larvae of the green lacewing Chrysoperla lucasina (Lacroix). The larvae of this predator are the only stage that feed on prey, thus ideally the supplemental food should result in high larval survival but a low developmental rate. Juvenile survival and developmental time of lacewing larvae were measured on various food items, either alone or mixed with mealybugs. Mealybugs were a suboptimal prey: up to 50 % of the lacewing larvae died before they reached the pupal stage and the developmental time was relatively long when feeding exclusively on mealybugs. Mixing mealybugs with supplemental prey increased larval survival, but also reduced larval developmental time and thereby the period in which the larvae could prey on mealybugs. Moreover, adding eggs of Ephestia kuehniella Zeller, which appeared to be of high quality for lacewings, reduced the consumption of mealybugs by lacewing larvae in the laboratory. The addition of the prey mite Acarus siro (L.) also reduced larval mortality, but did not reduce mealybug predation rates by lacewing larvae. Greenhouse trials showed better mealybug control by lacewing larvae with supplemental prey of low quality (prey mites) rather than alternative prey of high quality (Ephestia eggs). In conclusion, biological control of mealybugs by lacewing larvae was strongly affected by the nutritional quality of the supplemental food source.

    Nieuwe methoden van bestrijding van bodemplagen in de glastuinbouw en zomerbloemen
    Kruidhof, H.M. ; Vijverberg, Ruben ; Woelke, J.B. ; Bloemhard, C.M.J. ; Holstein, R. van; Leman, A. - \ 2016
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    tuinbouw - glastuinbouw - enchytraeidae - phalaenopsis - sciaridae - plecoptera - bestrijdingsmethoden - substraten - insectenplagen - zomerbloemen - sluipwespen - horticulture - greenhouse horticulture - enchytraeidae - phalaenopsis - sciaridae - plecoptera - control methods - substrates - insect pests - summer flowers - parasitoid wasps
    Doel van dit onderzoek is het ontwikkelen van bestrijdingsmethoden voor Lyprauta en Proceroplatus muggenlarven (“potwormen”) en het beperken van vraatschade aan Phalaenopsis orchideeën. Hiervoor wordt eerst meer basiskennis ontwikkelt over de biologie en leefwijze van de “potwormen”, en wordt er een kweekmethode ontwikkeld. Het onderzoek richt zich tevens op het ontwikkelen van een zogenaamde “push-pull” methode voor de bestrijding van rouwmuggen (Sciaridae) en oevervliegen (Scatella sp.). Poster van het PlantgezondheidEvent 2016.
    Masterplan tripsbestrijding in bloemisterijgewassen
    Messelink, G.J. ; Leman, A. ; Weel, P.A. van; Holstein, R. van; Vijverberg, Roland ; Kruidhof, H.M. ; Huang, T. ; Wiegers, G.L. ; Tol, R.W.H.M. van - \ 2016
    Wageningen : Wageningen UR Glastuinbouw - 1
    tuinbouw - glastuinbouw - endofyten - natuurlijke vijanden - bestrijdingsmethoden - frankliniella occidentalis - chrysanthemum - rosaceae - alstroemeria - amaryllis - potplanten - tomatenbronsvlekkenvirus - afdekken - vallen - windtunnels - horticulture - greenhouse horticulture - endophytes - natural enemies - control methods - frankliniella occidentalis - chrysanthemum - rosaceae - alstroemeria - amaryllis - pot plants - tomato spotted wilt virus - casing - traps - wind tunnels
    Het doel van dit project is om tot betere bestrijdingsstrategieën van trips in de sierteelt onder glas te komen door 1) een weerbaarder gewas met endofyten, 2) preventieve inzet van natuurlijke vijanden en 3) gedragsmanipulatie van volwassen tripsen. Deze pijlers worden vervolgens geïntegreerd tot een systeemaanpak. Poster van het PlantgezondheidEvent 2016.
    Biologische bestrijding van wol- en schildluis in de sierteelt onder glas
    Kruidhof, H.M. ; Messelink, G.J. ; Leman, A. ; Vijverberg, Roland - \ 2016
    Wageningen : Wageningen UR Glastuinbouw - 1
    tuinbouw - glastuinbouw - biologische bestrijding - sierteelt - cymbidium - rosaceae - planococcus citri - coccoidea - sluipwespen - predatoren - roofinsecten - thrips - coleoptera - horticulture - greenhouse horticulture - biological control - ornamental horticulture - cymbidium - rosaceae - planococcus citri - coccoidea - parasitoid wasps - predators - predatory insects - thrips - coleoptera
    Het doel van dit project is om de biologische bestrijding van wol-en schildluis te verbeteren met nieuwe inzetstrategieën van bestaande bestrijders en door opsporing van complementaire nieuwe bestrijders. Poster van het PlantgezondheidEvent 2016.
    Eutrophication, Nile perch and food-web interactions in south-east Lake Victoria
    Cornelissen, I.J.M. - \ 2015
    Wageningen University. Promotor(en): Johan Verreth, co-promotor(en): Leo Nagelkerke; R. Vijverberg. - Wageningen : Wageningen University - ISBN 9789462575660 - 163
    lates niloticus - eutrofiëring - voedselwebben - interacties - visserijbiologie - visstand - dynamica - fytoplankton - distributie - voedingsgedrag - victoriameer - tanzania - lates niloticus - eutrophication - food webs - interactions - fishery biology - fish stocks - dynamics - phytoplankton - distribution - feeding behaviour - lake victoria - tanzania

    The increasing eutrophication, the introduction of Nile perch (Lates niloticus) and the increasing fishing pressure has changed Lake Victoria tremendously the last century. Since the 1960s, eutrophication increased primary production, enabling an increase in fish production. However, eutrophication also created hypoxia pockets, which reduced the available habitats for fish. In addition, the endemic haplochromines declined, whereas the introduced Nile perch boomed in the 1980s. The Nile perch boom and increased fish production resulted in the largest freshwater fisheries of the world. However, it is unclear whether fish production can still increase with further eutrophication as maximum primary production rates may have been reached. Fish stocks fluctuate since the 1980s and in order to manage these, it is important to understand how eutrophication and fisheries affect the Nile perch population. The present study investigates the bottom-up effects of eutrophication on the Nile perch and food-web dynamics in south-east Lake Victoria. We analysed the level of eutrophication along an eutrophication gradient in the Mwanza Gulf. Phytoplankton biomass varied spatially and seasonally and was limited by nutrients in deep water and by light in shallow water. Fish distributions were dynamic, with environmental factors depth and temperature influencing Nile perch size structure and distribution patterns similarly on small and large spatial scales. Although prey densities of haplochromines and Caridina nilotica shrimp did not explain Nile perch distributions, ontogenetic diet shifts and composition were related to prey densities, suggesting an opportunistic feeding behaviour of Nile perch. Small Nile perch however, showed some preference to shrimp and Nile perch preferred haplochromines above Dagaa (Rastrineobola argentea) and juvenile Nile perch as fish prey. On a food-web level, the base of the food web was spatially and seasonally highly dynamic. The onset of rains caused a spatial differentiation in littoral/benthic and pelagic carbon sources, affecting the whole food web. Trophic levels of fish were related to the spatial variation in diet compositions. Although a large heterogeneity was found in water quality, fish distributions and food-web structure, bottom-up processes affected the food web similarly. Despite the ongoing nutrient load in Lake Victoria, water quality has improved since the 1990s. Climate forcing through increasing wind speeds increased visibility and oxygen levels. Global climate change will therefore be an important driver of the water quality and fish distributions of Lake Victoria.

    Detectie en bestrijding van wol- en schildluis in de sierteelt onder glas
    Messelink, G.J. ; Leman, A. ; Vijverberg, R. ; Kruidhof, H.M. ; Woning, J. ; Bruin, A. de; Mumm, R. ; Kogel, W.J. de - \ 2015
    Wageningen UR Glastuinbouw (Rapport GTB 1339) - 52
    glastuinbouw - plantenplagen - sierteelt - glasgroenten - organismen ingezet bij biologische bestrijding - bestrijdingsmethoden - planococcus citri - detectie - methodologie - landbouwkundig onderzoek - greenhouse horticulture - plant pests - ornamental horticulture - greenhouse vegetables - biological control agents - control methods - planococcus citri - detection - methodology - agricultural research
    Mealybugs and armoured scales are major pest species in ornamental crops in greenhouses. The first part of this report focuses on mealybug detection. The research presented here builds on previous study in which it was shown on laboratory scale that the odour profile released by plants after damage by mealybugs differs from the odour profile released by undamaged plants and plants that suffer from spider mite or mechanical damage. In the present study the change of several compounds in response to mealybug infection was shown to depend on a number of different factors: the growth stage of the plant (flowering/non-flowering), the time of the day sampling took place, the mealybug density and the duration of the mealybug infection. Although in each of the laboratory experiments several plant volatiles were found to significantly differ between mealybug-infested plants and control plants, so far no candidate indicator-volatiles have been found that always reacted significantly and in the same manner to a mealybug infection. The screening of new pesticides showed one pesticide to be effective against both the citrus mealybug Planococcus citri and the rose scale Aulacapsis rosae. Several isolates of entomopathogenic fungi were able to infect mealybugs in the laboratory, but results obtained in the greenhouse were disappointing. Lacewing larvae of the species Chrysoperla lucasina were able to control mealybugs when released repeatedly. The addition of Ephestia eggs disrupted this control in some cases.
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