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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    Understanding the role of oat ß-glucan in oat-based dough systems
    Londono, D.M. ; Gilissen, L.J.W.J. ; Visser, R.G.F. ; Smulders, M.J.M. ; Hamer, R.J. - \ 2015
    Journal of Cereal Science 62 (2015). - ISSN 0733-5210 - p. 1 - 7.
    rheological properties - celiac-disease - bread quality - pentosans - diet - formulations - yeast
    B-glucan is one of the components that differentiate oats from other cereals and that contribute to the health-related value of oats. However, so far oats cannot easily be applied in bread-like products without loss of product quality. Here we have studied how the content and viscosity of oat ß-glucan affect the technological properties of oat dough in both a gluten-free and a gluten-containing system. In both systems, increasing the ß-glucan concentration resulted in an increase of dough stiffness and in a reduction of dough extensibility. ¿-glucan negatively impacted the elastic properties that additional wheat gluten conferred to oat dough. This effect was smaller for medium-viscosity ß-glucan than for high-viscosity ß-glucan. Interestingly, dough made from low ß-glucan flour (
    Observational Support for the Stability Dependence of the Bulk Richardson Number across the Stable Boundary Layer
    Basu, S. ; Holtslag, A.A.M. ; Caporaso, L. ; Riccio, A. ; Steeneveld, G.J. - \ 2014
    Boundary-Layer Meteorology 150 (2014)3. - ISSN 0006-8314 - p. 515 - 523.
    self-correlation - resistance laws - surface fluxes - least-squares - model - height - regression - formulations - parameter - breakdown
    The bulk Richardson number (Ri Bh ; defined over the entire stable boundary layer) is commonly utilized in observational and modelling studies for the estimation of the boundary-layer height. Traditionally, Ri Bh is assumed to be a quasi-universal constant. Recently, based on large-eddy simulation and wind-tunnel data, a stability-dependent relationship has been proposed for Ri Bh . In this study, we analyze extensive observational data from several field campaigns and provide further support for this newly proposed relationship.
    Effect of enzyme dehydration on alcalase-catalyzed dipeptide synthesis in near-anhydrous organic media.
    Vossenberg, P. ; Beeftink, H.H. ; Cohen Stuart, M.A. ; Tramper, J. - \ 2013
    Biotechnology Progress 29 (2013)4. - ISSN 8756-7938 - p. 870 - 875.
    peptide-synthesis - fatty-acid - esterification - solvents - kinetics - water - deactivation - formulations - hydrolases
    The effect of enzyme dehydration by molecular sieves on the coupling of phenylalanine amide and the carbamoylmethyl ester of N-protected phenylalanine in near-anhydrous tetrahydrofuran was investigated. This coupling was catalyzed by Alcalase covalently immobilized onto macroporous acrylic beads (Cov); these immobilized enzymes were hydrated prior to use. The dehydration kinetics of Cov by molecular sieve powder were determined by incubating Cov with different amounts of molecular sieve powder for different periods of time (0-80 h). Subsequently, the remaining coupling activity of Cov was measured. Dehydration-induced inactivation of Cov by molecular sieve powder was found to occur in three phases: (1) an initial, rapid, major dehydration-induced inactivation that takes place during the first activity measurement, (2) a phase of first-order inactivation, and (3) a plateau phase in activity. These dehydration kinetics were incorporated into a previously found reaction kinetics model. The resulting model was then used to fit progress curve data of the coupling in the presence of different amounts of molecular sieve powder. Upon establishment of parameter values, the model was used to predict independent data sets and found to work well.
    Improving Stable Boundary-Layer Height Estimation Using a Stability-Dependent Critical Bulk Richardson Number
    Richardson, H. ; Basu, S. ; Holtslag, A.A.M. - \ 2013
    Boundary-Layer Meteorology 148 (2013)1. - ISSN 0006-8314 - p. 93 - 109.
    large-eddy simulation - turbulence structure - resistance laws - climate model - surface - depth - formulations - evolution - profile - range
    For many decades, attempts have been made to find the universal value of the critical bulk Richardson number (Ri Bc ; defined over the entire stable boundary layer). By analyzing an extensive large-eddy simulation database and various published wind-tunnel data, we show that Ri Bc is not a constant, rather it strongly depends on bulk atmospheric stability. A (qualitatively) similar dependency, based on the well-known resistance laws, was reported by Melgarejo and Deardorff (J Atmos Sci 31:1324–1333, 1974) about forty years ago. To the best of our knowledge, this result has largely been ignored. Based on data analysis, we find that the stability-dependent Ri Bc estimates boundary-layer height more accurately than the conventional constant Ri Bc approach. Furthermore, our results indicate that the common practice of setting Ri Bc as a constant in numerical modelling studies implicitly constrains the bulk stability of the simulated boundary layer. The proposed stability-dependent Ri Bc does not suffer from such an inappropriate constraint.
    Atomization of dilute oil-in-water emulsions during application of crop protection products
    Hilz, E. - \ 2013
    Wageningen University. Promotor(en): Martien Cohen Stuart; Frans Leermakers, co-promotor(en): A.W.P. Vermeer. - S.l. : s.n. - ISBN 9789461735416 - 199
    drift - spuiten - druppelstudies - verstuiving - druppelgrootte - formuleringen - pesticiden - emulsies - drift - spraying - droplet studies - atomization - droplet size - formulations - pesticides - emulsions

    Crop protection products are usually applied as sprays. These spray droplets have a certain size distribution. Fine droplets are often required to achieve a good coverage of the plant and to guarantee the biological efficacy of an agrochemical product. At the same time very fine droplets in spray are not desirable. Due to their low mass and velocity, these droplets can be carried from the application site by crosswind and e.g. can contaminate surface water. Droplet drift can be minimized by reducing the number of very fine droplets in spray. Dilute emulsions produce coarser sprays compared to water when atomized through a standard flat fan nozzle. For this reason dilute emulsions can reduce drift risk.

    The mechanism of spray formation of dilute emulsions has been investigated in this thesis. The proposed mechanism also describes spray formation in more complex mixtures of dilute emulsions with surfactants or polymers.

    Colloidal Protein Particles Can Be Used to Develop a Gluten-free Bread
    Riemsdijk, L.E. van; Goot, A.J. van der - \ 2011
    Cereal Foods World 56 (2011)5. - ISSN 0146-6283 - p. 201 - 204.
    rheological properties - celiac-disease - cold gelation - quality - flour - dough - batters - formulations - impact
    This paper presents a novel approach for the production of gluten-free breads. Rather than mimicking the molecular structure and properties of gluten, gluten functionality was mimicked by creating a colloidal protein particle network (based on whey protein). The addition of this protein particle network transformed a starch slurry into a material with dough-like properties that could be used in a standard baking process to produce gluten-free breads. An overview of the potential and limitations of this novel technology is given.
    Lignin based controlled release coatings
    Mulder, W.J. ; Gosselink, R.J.A. ; Vingerhoeds, M.H. ; Harmsen, P.F.H. ; Eastham, D. - \ 2011
    Industrial Crops and Products 34 (2011)1. - ISSN 0926-6690 - p. 915 - 920.
    slow-release - kraft lignin - fertilizer - formulations - urea - polymers - sorghum
    Urea is a commonly used fertilizer. Due to its high water-solubility, misuse easily leads to excess nitrogen levels in the soil. The aim of this research was to develop an economically feasible and biodegradable slow-release coating for urea. For this purpose, lignin was selected as coating material. From four commercially available lignins, two lignosulfonates (Wafex P and Borresperce), a softwood kraft (Indulin AT) and soda flax lignin (Bioplast), the latter showed the best potential with respect to film forming properties. Bioplast dispersions up to a dry matter content of 50% are processable. However, high losses during processing resulted in thin coating layers on the urea granules. To reduce urea release, hydrophobic compounds and crosslinkers were added to the Bioplast dispersions. Addition of alkenyl succinic anhydride (ASA) significantly decreased the release of urea in water. However, complete release of urea still occurred within one hour, which can be explained by a low reactivity of the selected compounds towards lignin, too low percentages of applied coating or negative effects of the selected compounds on the film forming process. In addition, urea partly dissolves in the aqueous lignin dispersions due to its high water-solubility. This causes incorporation of urea in the lignin layer, which results in coatings with a low water resistance. This was improved by application of an inner coating layer with high dry matter content. In conclusion, lignin shows high potential as coating material. For industrial application, more insight in the film forming properties is desired.
    A novel method to prepare gluten-free dough using a meso-structured whey protein particle system
    Riemsdijk, L.E. van; Pelgrom, P.J.M. ; Goot, A.J. van der; Boom, R.M. ; Hamer, R.J. - \ 2011
    Journal of Cereal Science 53 (2011)1. - ISSN 0733-5210 - p. 133 - 138.
    rheological properties - bread quality - simple shear - microstructure - hydrocolloids - formulations - behavior - flow
    This paper presents a novel concept for making an elastic dough using a structured protein suspension. The idea behind it is based on the hypothesis that a number of gluten properties originate from a particle structure present in the gluten network. Three different mesoscopically structured whey protein suspensions were produced: whey protein aggregates, a whey protein cold set gel and whey protein particles. Dough mixtures or batters were prepared by mixing the structured protein particle suspension with starch. Farinograph curves, small and large deformation experiments showed that the presence of a mesoscopic protein structure had a large impact on the properties of gluten-free starch mixtures. The whey protein that was structured into a mesoscopic particle suspension changed the starch mixture from a liquid into a cohesive material, having strain hardening properties.
    Preparation of gluten-free bread using a meso-structured whey protein particle system
    Riemsdijk, L.E. van; Goot, A.J. van der; Hamer, R.J. ; Boom, R.M. - \ 2011
    Journal of Cereal Science 53 (2011)3. - ISSN 0733-5210 - p. 355 - 361.
    rheological properties - gas retention - dough - flour - stabilization - formulations - quality
    This article presents a novel method for making gluten-free bread using mesoscopically structured whey protein. The use of the meso-structured protein is based on the hypothesis that the gluten structure present in a developed wheat dough features a particle structure on a mesoscopic length scale (100 nm–100 µm). Whey protein particles were prepared by cold gelation of soluble whey protein aggregates during phase separation. The addition of a 2.4% whey protein particle suspension to wheat starch resulted in a dough that could be baked into a leavened bread with a specific volume up to 3.7 ml/g and a bubble size comparable with a normal bread. The relevance for structuring the whey protein into mesoscopic particles was confirmed by tests in which only a homogeneous whey protein gel or a whey protein solution was used. The protein particle system gave better results after proving and baking compared with these systems.
    Micropropagation of dahlia in static liquid medium using slow-release tools of medium ingredients
    Klerk, G.J.M. de; Brugge, J. ter - \ 2011
    Scientia Horticulturae 127 (2011)4. - ISSN 0304-4238 - p. 542 - 547.
    tissue-cultures - suspension-cultures - growth - calcium - formulations - nutrition - segments - necrosis - invitro - apple
    Growth of dahlia shoots in vitro was ca. 4 times faster in liquid medium than on solidified medium. In liquid standard medium (3% sucrose, macroelements according to Driver–Kuniyuki Walnut medium, microelements according to Murashige–Skoog medium, 0.44 µM benzylaminopurine), the major medium ingredients were consumed for 75–80% during the first 6 weeks. Addition of extra ingredients increased growth, demonstrating that the amount of ingredients added at the start of culture was suboptimal. When the extra ingredients were given at the start of the culture, concentrations became too high and therefore inhibitory. When the ingredients were added during the subculture cycle by means of small aliquots of a concentrated solution or by means of slow-release tools, growth was strongly increased. Osmocote gave satisfactory results as a slow-release tool for inorganics. For organic ingredients (sucrose and benzylaminopurine), a novel slow-release tool was developed.
    Emergent technologies against the background of everyday life: Discursive psychology as a technology assessment tool
    Veen, M. ; Gremmen, H.G.J. ; Molder, H.F.M. te; Woerkum, C.M.J. van - \ 2011
    Public Understanding of Science 20 (2011)6. - ISSN 0963-6625 - p. 810 - 825.
    celiac-disease - science - discourse - knowledge - talk - communication - formulations - controversy - experts - health
    To understand prospective users’ reactions to emergent technologies, it is crucial to examine the interactional contexts within which these reactions take place as people’s reactions are shaped by issues that are not necessarily related to science or technology. These issues are often overshadowed or remain blind spots when descriptions or scenarios of proposed technologies are thematized as being the core objects of reference. We therefore recommend also studying prospective users’ everyday-life practices in their own right, and in naturalistic settings. Insight into the social actions people accomplish in their everyday talk, such as establishing a particular identity, can help innovators translate prospective users’ concerns into relevant technology characteristics. We propose discursive psychology as an analytic tool to do this and show its merit with a few illustrative examples
    Optimization of formulation and delivery technology of entomopathogenic fungi for malaria vector control
    Mnyone, L.L. - \ 2010
    Wageningen University. Promotor(en): Willem Takken; Marcel Dicke. - [S.l.] : S.n. - ISBN 9789085857877 - 125
    culicidae - vectoren, ziekten - malaria - vectorbestrijding - entomopathogene schimmels - biologische bestrijding - toepassing - formuleringen - culicidae - disease vectors - malaria - vector control - entomogenous fungi - biological control - application - formulations
    Vector control is one of the most effective means of controlling mosquito-borne diseases such as malaria. The broad goal of this strategy is to protect individuals against infective mosquito bites and, at the community level, to reduce the intensity of disease transmission. With the deployment of mainly insecticide-treated nets (ITN) and indoor residual spraying (IRS), aided by effective drug treatment, certain countries particularly those within the low endemic zones have documented more than 50% reduction in malaria cases over the past decade. To keep up the pace and expand effective malaria control, in line with the global effort to eliminate malaria, IRS and ITN need to be complemented with alternative control methods. Indeed, neither long lasting insecticide nets (LLINs) nor IRS alone will be sufficient to achieve and maintain interruption of transmission in malaria holoendemic and hyperendemic areas. Besides, the sustainability of both methods is inescapably threatened by mosquito resistance to insecticides. Scientific evidence indicates that biological control based on entomopathogenic fungi has the potential to complement existing vector control methods. Two species of entomopathogenic fungi, Metarhizium anisopliae and Beauveria bassiana, have demonstrated ability to infect and kill adult malaria vectors.

    This thesis describes the results of a series of laboratory investigations followed by small scale field trials in Tanzania in an area of high malaria endemicity, with abundant populations of the malaria vector Anopheles gambiae sensu lato. The overall aim was to optimize fungal formulations, develop delivery techniques that maximize fungus infection rates in wild malaria populations, evaluate impact on survival of these mosquitoes and asses the impact on malaria transmission levels. A series of variables that we hypothesized affect the efficacy and persistence of the fungal isolates Metarhizium anisopliae ICIPE-30, M. anisopliae IP 46 and Beauveria bassiana I93-825 against adult An. gambiae were assessed. These included a) conidia concentration (1×107- 4×1010 conidia m-2), b) exposure time (15 min - 6 h), c) delivery substrates (netting, cotton cloth & mud wall), d) mosquito age (2 - 12 d), e) time since blood meal (3 - 72 h) as well as f) mosquito behaviour (repellency by conidial formulations). Co-formulations of M. anisopliae ICIPE-30 and B. bassiana I93-825 in ratios of 4:1, 2:1 & 1:1 were also tested. Metarhizium anisopliae IP 46 was exposed to An. gambiae and An. arabiensis to determine its pathogenicity on these mosquito species before being used for the field trials. Mosquitoes were exposed to fungal formulations applied on paper inside holding tubes, except when different delivery substrates were assessed. For the delivery substrates, sections of netting and black cotton cloth were joined using Velcro strips to fit over 20 × 20 × 20 cm wire frame cages; and mud-lined plywood panels were similarly assembled into 20 × 20 × 20 cm cages. Laboratory experiments were performed using laboratory reared mosquitoes at the Ifakara Health Institute, Ifakara, Tanzania. Following the laboratory experiments, fungal formulations were assayed in experimental hut trials in a field setting at Lupiro village (Ulanga District, Tanzania), a rural hamlet 30 km south of Ifakara. Five different techniques that each exploited the behaviour of mosquitoes when entering (eave netting, eave curtains, eave baffles), host-seeking (cloth strips hung next to bed nets) or resting (cloth panels) were assessed.

    The degree at which mosquito survival was reduced varied with conidia concentration; 2×1010 conidia m-2 was the optimum concentration above which no further reductions in survival were detectable. Co-formulations exerted neither synergistic nor additive effect in reducing mosquito survival. The exposure of mosquitoes to fungal formulations for time periods as short as 15 and 30 min was adequate to achieve 100% mortality of mosquitoes within 14 d post exposure. Longer exposure times did not result in a more rapid killing effect. Conidia impregnated on papers remained infective up to 28 d post application, and such trait did not seem to be influenced by the conidia concentration. Mosquitoes of the age between 2-12 d equally succumbed to fungus infection, with them, however, being relative more susceptible when non-blood fed. Oil-formulations of the fungi did not exhibit any repellency to mosquitoes. Metarhizium anisopliae IP 46 was pathogenic to both An. gambiae and An. arabiensis. Conidia were more effective when applied on mud panels and cotton cloth compared with polyester netting. Cotton cloth and mud, therefore, represent potential surfaces for delivering fungi to mosquitoes in the field.
    Two delivery techniques, cotton cloth eave baffles and strips hung next to the bed net were successful in exploiting the behaviour of wild anopheline mosquitoes. Up to 75% of house-entering mosquitoes became infected with fungus applied with either technique. By contrast, eave netting, eave curtains and cotton panels placed next to the bed net were ineffective in infecting mosquitoes with sufficiently high doses of fungi to affect their survival. Based on the survival data of the mosquitoes infected with fungus by means of eave baffles, model estimates indicated that fungus alone can reduce EIR by more than 75%.

    In conclusion, these findings indicate that with well-optimized fungal formulations and correctly-designed delivery techniques, a high proportion of house-entering wild malaria mosquitoes can be infected with entomopathogenic fungi to achieve considerable reduction in their survival and possibly malaria transmission. More importantly, these findings provide baseline information that is highly relevant for designing and conducting large-scale field trials to validate the projected impact of fungal infection under realistic field situations.

    Selection of phosphorus solubilizing bacteria with biocontrol potential for growth in phosphorus rich animal bone charcoal
    Postma, J. ; Nijhuis, E.H. ; Sommeus, E. - \ 2010
    Applied Soil Ecology 46 (2010)3. - ISSN 0929-1393 - p. 464 - 469.
    pythium-aphanidermatum - rhizoctonia-solani - damping-off - plant - root - soil - management - suppressiveness - microorganisms - formulations
    Bacteria with the ability to solubilize phosphorus (P) and to improve plant health were selected and tested for growth and survival in P-rich animal bone charcoal (ABC). ABC is suggested to be suitable as a carrier for biocontrol agents, offering them a protected niche as well as delivering phosphate to plants, meanwhile re-using P from waste of the food chain. Ninety-seven bacterial isolates from different soils were tested for their potential to dissolve P from ABC. Of these isolates, 60% showed positive scores; they belonged to the genera Arthrobacter, Bacillus, Burkholderia, Collimonas, Paenibacillus, Pseudomonas, Serratia, and Streptomyces. Twelve isolates from different taxonomic groups were selected for further research on growth ability and survival in ABC, and on their potential to control plant pathogens. The highest concentrations of P were dissolved by Pseudomonas chlororaphis and Bacillus pumilus, followed by Paenibacillus polymyxa, Burkholderia pyrrocinia and three Streptomyces isolates. P. chlororaphis and P. polymyxa showed strongest growth inhibition of plant pathogenic Pythium and Fusarium sp., followed by the Streptomyces spp. isolates. Research highlights Describes a stepwise selection procedure with the aim to find beneficial bacteria that can grow in animal bone charcoal (ABC). This research was part of an EU project, with the aim to recycle and upgrade waste from the food chain. The results show that several interesting beneficial bacteria could proliferate and survive in this ABC carrier. Keywords: Biological control; Phosphorus mobilization; Antagonistic bacteria; Animal bone charcoal; Pythium aphanidermatum; Fusarium oxysporum f.sp. radicis lycopersici
    The development of microbial pest control products for control of arthropods: a critical evaluation and a roadmap to success
    Ravensberg, W.J. - \ 2010
    Wageningen University. Promotor(en): Joop van Lenteren. - [S.l.] : S.n. - ISBN 9789085856788 - 348
    plagen veroorzaakt door geleedpotigen - biopesticiden - ontwikkeling - potentie - screenen - biologische productie - formuleringen - experimenteel veldonderzoek - kwaliteitscontroles - vercommercialisering - planning - toelating van bestrijdingsmiddelen - arthropod pests - microbial pesticides - development - potency - screening - biological production - formulations - field experimentation - quality controls - commercialization - planning - authorisation of pesticides
    Microbial pesticides have been developed for a hundred years, but many of these biological crop protection products have not been successful in the market. This is illustrated in chapter 1 by the history of microbial pest control products and the biopesticide companies producing those. In this thesis I recognize the need for a model that would facilitate the development and commercialization of biopesticides based on entomopathogenic bacteria, fungi, viruses, and nematodes. The aim of this thesis was to develop a rational and structured approach that will increase the chances of achieving success with microbial pest control products for control of arthropods.
    The initial step is finding a microbial pest control agent which has the potential to control the pest (chapter 2). The search for a novel agent is directed by an elaborate description of the pest problem. The first level of selection is the type of entomopathogen: bacteria, fungi, viruses, protozoa, and entomopathogenic nematodes. The second level is at the species and strain level. This study identified three decisive selection criteria for a commercial microbial insecticide: mortality, production efficiency, and safety to humans and the environment. The consecutive steps in the screening process have been identified as the collection of isolates, laboratory screening on efficacy in well-standardized bio-assays, and on production efficiency, assessment of mode of action and toxicological properties, and efficacy in small glasshouse trials. This selection process should deliver determinative information on which one or at the most three to four strains are chosen for further development.
    The next phase is the investigation of the feasibility of economic mass production of the selected strain(s) and the development of a stable product (chapter 3). Two phases are distinguished, the development of the production process, including medium development and downstream processing, and the development of the product, including formulation, packaging and field testing. Mass production is preferably an in vitro process because that offers more control than an in vivo process. Bacteria, fungi and entomopathogenic nematodes are generally produced in vitro, whereas baculoviruses must be produced in vivo. The critical technical and economic factors are identified and evaluated for these four types of pathogens. The goal is to produce the greatest number of infective propagules for the lowest cost.
    A stable product requires a formulation. The four main objectives in formulating the infective propagules are: to stabilize the propagules for reasons of packaging, shelf-life and shipping; to create a user-friendly product that can be effectively delivered to the target; to protect the propagule, once applied, to improve its persistence at the target site; and to minimize risks of exposure to the applicator. Formulation considerations and recommendations are presented per formulation function as well as per type of pathogen.
    Field testing links all steps in the developmental process. It provides information on the efficacy of the selected strain, on the quality of the produced propagules, on the formulation, and on the optimal application strategy. Results from field tests provide a continuous circle of feedback that allows improvement of each of the steps of the entire developmental process.
    The price of a product is an essential element and a cost price model for biopesticides is presented. The model provides a perspective on the makeup of the end-user’s price. Economy of scale, full use of the production capacity, and capacity planning are pivotal factors to keep the costs low. Key elements to successful biopesticides are both production efficiency and product efficacy.
    Quality control (chapter 4) provides feedback on the production and formulation processes, and on the final product. The continuous process of improvements will ultimately decrease costs and improve performance of the production system and the product. Products must meet product specifications. Parameters checked per batch are the number of effective propagules, microbial purity, presence of toxins, technical properties and efficacy. Standardization and comparison with a reference product are prerequisites for proper quality control. Quality control is also required for registration, but standard methods and criteria are lacking. Therefore, guidance documents need to be developed. Biocontrol companies should ensure that product quality is maintained through the whole distribution chain and that end-users receive high quality products. I showed that in that way, both the biocontrol industry and its customers benefit from proper quality control.
    In chapter 5 regulations for microorganisms are reviewed. Microorganisms, except nematodes, need to be registered as plant protection products for crop protection. Registration is perceived as the main hurdle to the development of a biopesticide. The procedures in the EU are presented and difficulties discussed. The issues relate to inappropriate data requirements, lack of guidance for applicants and regulators, testing methods for microbials, lack of experience in regulators, national registration procedures, and the inexperienced small biopesticide companies. Registration is expensive and takes many years. I presented registration cost estimates for each type of entomopathogenic product. Initiatives for improvements from the EU-REBECA project, from the OECD BioPesticides Steering Group, and some national projects are presented. I also provided recommendations for improvements for data requirements and regulatory procedures. New regulations may offer improved procedures in the near future. Various import and export regulations affect the use of microorganisms, and the need for harmonization is emphasized. The Convention of Biodiversity may, through Access and Benefit Sharing, create a further impediment for biocontrol.
    The patentability of an entomopathogen is discussed as well as the criteria for granting a patent: novelty, inventive step, and industrial applicability. I also discussed costs and other considerations whether to apply for a patent for a biopesticide.
    The implementation strategy of the product in an IPM programme is a basic element of the use of any microbial pest control product (chapter 6). Three phases are distinguished: the optimal application strategy of the product, the incorporation of the microbial pest control product in an IPM system, and a carefully designed adoption strategy. Determinative parameters for each phase, and for each type of product are identified. For instance, for a successful use, the compatibility with chemical pesticides and with natural enemies and pollinators needs to be investigated. Furthermore, knowledge transfer and training are pivotal elements. All stakeholders need to participate in this process.
    These phases require a considerable amount of research which should be conducted before market launch. Recommendations are provided for a tiered approach which results in reliable information for commercial conditions. Many companies underestimated or even neglected this part of product development. In my opinion, these phases are paramount for good market introduction. I reported the most relevant requirements for successful use of a microbial pest control product. Successful implementation of a microbial pest control product depends on how well relevant interactions are studied and translated into practical recommendations for the grower. This phase continues after market introduction. It requires a continuous effort from producer, distributor and customer to ensure that product adoption will increase and satisfied customers will remain using the new product in their IPM system.
    In chapter 7, I noted that commercialization is the final and most difficult step in the development and the market introduction of a microbial pest control product. The factors that determine success or failure are identified for a company as well as for a product, and recommendations are provided that will facilitate success.
    Figures on the global biopesticide market are reviewed. The European market is estimated to be €57 million at end-user level, and the market in the Netherlands at €5-6 million. The European biopesticide market comprises less than 1% of the total European crop protection market. Biopesticides are predominantly used in protected crops and in orchards.
    Companies which contemplate the development and commercialization of a biopesticide need realistic data on five key aspects to make their decision: market demand, market size, profit margin, time to market, and time to volume. The biggest mistake companies still make today is a misjudgement of the potential market size and the expected market adoption rate. I proposed the use of a stage-gate process with objective, quantifiable, and transparent tools in decision-making. Examples of scorecards are presented to quantify decisions. The business model that performs best at present seems to be a small company which follows an incremental and manageable growth of the organization. Total developmental costs and time to market are significant factors of a company’s success. Costs amount to € 10-15 million for a company that still needs to be built; while in an existing company, costs may reach € 5-10 million for a biopesticide project. Time to market including registration is five to seven years. I have identified five determinants for successful commercialization: 1) acceptable expenses and time to market; 2) a high quality product; 3) a sufficiently large market; 4) a profit margin that allows expansion in new markets and products; and 5) the appropriate business approach.
    A new product development project is extensive and it is difficult to oversee. In chapter 8 I have made an analysis of the various phases and I highlighted the most important topics in the development and commercialization of a microbial pest control product. This study demonstrated that the development of a microbial pest control product requires a structured project plan. The building blocks of the entire process are defined and essential factors emphasized. From this, I have divided the process in phases and steps, and designed the roadmap to a successful product. Three diagrams illustrate the stepwise approach of the entire process, the selection phase, the product development phase, and the implementation phase. Registration and commercialization are processes that relate to these phases during the entire developmental process.
    A future perspective on the biopesticide market is presented with limiting and promotional factors and trends. The significant drivers for success are food safety concern, changes in the regulatory climate, biodiversity and environmental issues, new research and technology, and the occurrence of new invasive pests. The biopesticide industry has reached a sufficient level of maturity and critical mass to form a base for further expansion. This will allow the biopesticide market to steadily grow. The roadmap proposed in this study will assist developers of biopesticides in accomplishing their goals in a cost- and time-effective way, which will result in successful and sustainable products and expanding biocontrol companies.

    Modeling desorption kinetics of a persistent organic pollutant from field aged sediment using a bi-disperse particle size distribution
    Smit, M.P.J. ; Grotenhuis, J.T.C. ; Bruning, H. ; Rulkens, W.H. - \ 2010
    Journal of Soils and Sediments 10 (2010)1. - ISSN 1439-0108 - p. 119 - 126.
    long-term sorption - contaminant desorption - slow desorption - mass-transfer - flood events - soil - diffusion - equilibrium - river - formulations
    Purpose With the predicted climate change, it is expected that the chances of river flooding increase. During flood events, sediments will resuspend and when sediments are polluted, contaminants can be transferred to the surrounding water. In this paper we discuss a numerical intraparticle diffusion model that simulates desorption of dieldrin from a suspension of contaminated porous sediment particles with a well-characterized particle size distribution. The objective of this study was to understand the desorption rate (flux) of dieldrin from a suspension of field-aged sediment at different hydraulic retention times (HRT) of the aqueous phase and to elaborate the effect of particle-size distribution on mass transfer. Materials and methods Desorption kinetics of dieldrin, a persistent organic pollutant (POP), were experimentally measured and described in a separate paper using field-contaminated sediment. A radial diffusion model, accommodating intraparticle reversible sorption kinetics, aqueous phase pore diffusion, and a sink term for bulk aqueous phase refreshment was used to describe the experimental data. Results and discussion We observed rapid equilibrium of contaminants between small particles (10 µm) and the surrounding water even though the sorption affinity of dieldrin towards organic matter was high. On the contrary, for the larger particles (84 µm), calculations show that desorption was limited by intraparticle diffusion. Combining small and larger particles in our radial diffusion model resulted in the biphasic desorption behavior often observed even when using a linear isotherm. Conclusions Flood events will result in an increase of desorption rate of POPs from sediments to the surrounding water. HRT and the particle-size distribution determine the desorption rate. We conclude that nonstationary diffusion within organic matter is the main process of mass transfer. Particle size distributions are very valuable to understand the phenomenology related to mass transfer limitations often described as limited bioavailability and can be used as basis to develop engineering options to limit contaminant mass fluxes into the environment
    The use of aggregation pheromone to enhance dissemination of Beauveria bassiana for the control of the banana weevil in Uganda
    Tinzaara, W. ; Gold, C.S. ; Dicke, M. ; Huis, A. van; Nankinga, C.M. ; Kagezi, G.H. ; Ragama, P.E. - \ 2007
    Biocontrol Science and Technology 17 (2007)2. - ISSN 0958-3157 - p. 111 - 124.
    cosmopolites-sordidus - entomopathogenic fungi - musa spp. - coleoptera - field - autodissemination - curculionidae - formulations - populations - beetle
    Candidate strains of Beauveria bassiana were identified for use in integrated pest management of the banana weevil Cosmopolites sordidus. Horizontal field transmission of B. bassiana between banana weevils using different delivery systems, including aggregation pheromones, was investigated. We observed that infected weevils could transmit the fungal pathogen to healthy individuals. Most dead weevils (52%) due to B. bassiana infection were found at the base of banana plants in the leaf sheath or in the soil near banana plants. Significantly more weevils died from the pathogen in plots where B. bassiana was applied in combination with the pheromone than where it was applied alone. Our data demonstrate that C. sordidus aggregation pheromone can be a valuable tool to enhance the dissemination of B. bassiana for the control of C. sordidus.
    Diagnostic equations for the stable boundary-layer height: evaluation and dismensional analysis
    Steeneveld, G.J. ; Wiel, B.J.H. van de; Holtslag, A.A.M. - \ 2007
    Journal of Applied Meteorology and Climatology 46 (2007). - ISSN 1558-8424 - p. 212 - 225.
    grenslaag - vergelijkingen (wiskundig) - prestatieniveau - meteorologische waarnemingen - grenslaagmeteorologie - boundary layer - equations - performance - meteorological observations - boundary-layer meteorology - nocturnal surface inversion - large-eddy simulations - mixing height - equilibrium depth - model - turbulence - formulations - variability - sensitivity - parameters
    The performance of diagnostic equations for the stable boundary layer height h is evaluated with four observational datasets that represent a broad range of latitudes, land use, and surface roughness. In addition, large-eddy simulation results are used. Special care is given to data-quality selection.
    The performance of diagnostic equations for the stable boundary layer height h is evaluated with four observational datasets that represent a broad range of latitudes, land use, and surface roughness. In addition, large-eddy simulation results are used. Special care is given to data-quality selection. The diagnostic equations evaluated are so-called multilimit equations as derived by Zilitinkevich and coworkers in a number of papers. It appears that these equations show a serious negative bias, especially for It <100 m, and it was found that the parameters involved could not be determined uniquely with calibration. As an alternative, dimensional analysis is used here to derive a formulation for h that is more robust. The formulation depends on the surface friction velocity u(*), surface buoyancy flux B-s, Coriolis parameter, and the free-flow stability N. The relevance of the Coriolis parameter for the boundary layer height estimation in practice is also discussed. If the Coriolis parameter is ignored, two major regimes are found: h similar to u(*)/N for weakly stable conditions and h similar to (vertical bar B-N vertical bar/N-3)(1/2) for moderate to very stable conditions.
    Toedieningswijze en formulering cruciaal voor effectiviteit van GNO's
    Zande, J.C. van de; Stevens, L.H. ; Spits, H.G. - \ 2006
    gewasbescherming - pesticiden - plantaardige pesticiden - biopesticiden - toedieningswijzen - doseringseffecten - formuleringen - bladbespuiting - aardappelen - lelies - appels - toelating van bestrijdingsmiddelen - plant protection - pesticides - botanical pesticides - microbial pesticides - application methods - dosage effects - formulations - foliar spraying - potatoes - lilies - apples - authorisation of pesticides
    Succesvolle introductie van GNO’s in de praktijk is in hoge mate afhankelijk van een juiste toedieningswijze en daarmee samenhangende formulering. Verbetering van de effectiviteit verlaagt de benodigde hoeveelheid GNO’s, waardoor de kans op introductie wordt verhoogd. Onderzoek naar toediening en formulering is daarom een integraal onderdeel van de ontwikkeling van GNO-produkten voor de praktijk
    Foliar absorption of crop protection agents: influence of cpa properties, formulation and plant species : a literature study for the Dutch research programme pesticides and the environment (DWK-359) theme B-2
    Ruiter, H. de; Kempenaar, C. ; Blom, M. - \ 2004
    Wageningen : Plant Research International (Report / Plant Research International 77) - 26
    4-cpa - opname via bladeren - formuleringen - veldgewassen - eenzaadlobbigen - tweezaadlobbigen - 4-cpa - foliar uptake - formulations - field crops - monocotyledons - dicotyledons
    Field inactivation of wild-type and genetically modified Helicoverpa armigera single nucleocapsid nucleopolyhedrovirus in cotton
    Sun, X. ; Sun, X.C. ; Werf, W. van der; Vlak, J.M. ; Hu, Z.H. - \ 2004
    Biocontrol Science and Technology 14 (2004)2. - ISSN 0958-3157 - p. 185 - 192.
    nuclear polyhedrosis-virus - heliothis - sunlight - lepidoptera - susceptibility - formulations - insecticide - toxin - moth
    Cotton bollworm (Helicoverpa armigera) is a serious pest on cotton in China. A specific baculovirus, H. armigera nucleopolyhedroviruses (HaSNPV) is used as a commercial biopesticide to control this pest. To improve the pesticidal properties, HaSNPV has been genetically engineered by both deleting the ecdysteroid UDP-glucosyltransferase (egt) gene from its genome (recombinant HaSNPV-EGTD) and incorporating an insect-selective toxin gene from the scorpion Androctonus australis (AaIT) (recombinant HaSNPV-AaIT). In the field, there was no significant difference among the inactivation rates of the two recombinant HaSNPVs and their parent wild-type, HaSNPV-WT. The inactivation rate of these viruses was significantly different in different years. The average half-life of HaSNPV was 0.57, 0.90 and 0.39 days in 2000, 2001 and 2002, respectively. Inactivation rates correlated well with solar radiation over these years.
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