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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Data from: Equivalence analysis to support environmental safety assessment: using nontarget organism count data from field trials with cisgenically modified potato
Voet, H. van der; Goedhart, P.W. ; Lazebnik, E. ; Kessel, G.J.T. ; Mullins, Ewen ; Loon, J.J.A. van; Arpaia, Salvatore - \ 2019
This paper considers the statistical analysis of entomological count data from field experiments with genetically modified (GM) plants. Such trials are carried out to assess environmental safety. Potential effects on nontarget organisms (NTOs), as indicators of biodiversity, are investigated. The European Food Safety Authority (EFSA) gives broad guidance on the environmental risk assessment (ERA) of GM plants. Field experiments must contain suitable comparator crops as a benchmark for the assessment of designated endpoints. In this paper, a detailed protocol is proposed to perform data analysis for the purpose of assessing environmental safety. The protocol includes the specification of a list of endpoints and their hierarchical relations, the specification of intended levels of data analysis, and the specification of provisional limits of concern to decide on the need for further investigation. The protocol emphasizes a graphical representation of estimates and confidence intervals for the ratio of mean abundances for the GM plant and its comparator crop. Interpretation relies mainly on equivalence testing in which confidence intervals are compared with the limits of concern. The proposed methodology is illustrated with entomological count data resulting from multiyear, multilocation field trials. A cisgenically modified potato line (with enhanced resistance to late blight disease) was compared to the original conventional potato variety in the Netherlands and Ireland in two successive years (2013, 2014). It is shown that the protocol encompasses alternative schemes for safety assessment resulting from different research questions and/or expert choices. Graphical displays of equivalence testing at several hierarchical levels and their interpretation are presented for one of these schemes. The proposed approaches should be of help in the ERA of GM or other novel plants.
Equivalence analysis to support environmental safety assessment: Using nontarget organism count data from field trials with cisgenically modified potato
Voet, Hilko van der; Goedhart, Paul W. ; Lazebnik, Jenny ; Kessel, Geert J.T. ; Mullins, Ewen ; Loon, Joop J.A. van; Arpaia, Salvatore - \ 2019
Ecology and Evolution 9 (2019)5. - ISSN 2045-7758 - p. 2863 - 2882.
This paper considers the statistical analysis of entomological count data from field experiments with genetically modified (GM) plants. Such trials are carried out to assess environmental safety. Potential effects on nontarget organisms (NTOs), as indicators of biodiversity, are investigated. The European Food Safety Authority (EFSA) gives broad guidance on the environmental risk assessment (ERA) of GM plants. Field experiments must contain suitable comparator crops as a benchmark for the assessment of designated endpoints. In this paper, a detailed protocol is proposed to perform data analysis for the purpose of assessing environmental safety. The protocol includes the specification of a list of endpoints and their hierarchical relations, the specification of intended levels of data analysis, and the specification of provisional limits of concern to decide on the need for further investigation. The protocol emphasizes a graphical representation of estimates and confidence intervals for the ratio of mean abundances for the GM plant and its comparator crop. Interpretation relies mainly on equivalence testing in which confidence intervals are compared with the limits of concern. The proposed methodology is illustrated with entomological count data resulting from multiyear, multilocation field trials. A cisgenically modified potato line (with enhanced resistance to late blight disease) was compared to the original conventional potato variety in the Netherlands and Ireland in two successive years (2013, 2014). It is shown that the protocol encompasses alternative schemes for safety assessment resulting from different research questions and/or expert choices. Graphical displays of equivalence testing at several hierarchical levels and their interpretation are presented for one of these schemes. The proposed approaches should be of help in the ERA of GM or other novel plants.
Unintended effects of a Phytophtora-resistant cisgenic potato clone on the potato aphid Macrosiphum euphorbiae and its parasitoid Aphidius ervi
Cascone, P. ; Radkova, M. ; Arpaia, S. ; Errico, S. ; Lotz, L.A.P. ; Magarelli, R.A. ; Djilianov, D. ; Guerrieri, E. - \ 2018
Journal of Pest Science 91 (2018)2. - ISSN 1612-4758 - p. 565 - 574.
Environmental risk assessment - Genetically modified plants - In planta tests - Non-target organisms - Tritrophic interactions - Unintended effects
Genetically modified (GM) plants may show unintended differences compared to the original varieties, due to the modification process. Such differences might in some cases affect non-target organisms linked to the crop into an agro-ecosystem. In this paper, we aimed to study interactions of two blight-resistant GM potato clones with the aphid species Macrosiphum euphorbiae Thomas, a non-target arthropod frequently feeding on potato plants and one of the major pests of that crop. One of the potato events used in our experiments caused an increased fertility of the aphids in the first generation, and consequently, a positive effect on the growth of the aphid population was estimated. When a second generation of the aphid was reared on potato leaves of the same GM event, differences in aphid fertility were no longer observed. Behavioural studies conducted in a wind tunnel using the aphid parasitoid Aphidius ervi Haliday indicated that neither of the two tested GM varieties had a significant effect on the attractiveness of potato plants towards the parasitoid. In planta tests proved to be sensitive protocols to detect unintended effects on a non-target arthropod; experimental results, however, indicate that these effects are not expected to be biologically relevant in this tritrophic system, if these GM events become available for commercial use in the future.
Effects of a genetically modified potato on a non-target aphid are outweighed by cultivar differences
Lazebnik, Jenny ; Arpaia, Salvatore ; Baldacchino, Ferdinando ; Banzato, Paolo ; Moliterni, Stefania ; Vossen, Jack H. ; Zande, Els M. van de; Loon, Joop J.A. van - \ 2017
Journal of Pest Science 90 (2017)3. - ISSN 1612-4758 - p. 855 - 864.
Environmental risk assessment - Genetic modification - Greenhouse - Myzus persicae - Non-target testing - Phytophthora infestans - Solanum tuberosum
Insect–plant interactions may be unintentionally affected when introducing genetically modified (GM) crops into an agro-ecosystem. Our aim was to test the non-target effects of a late blight-resistant GM potato on Myzus persicae in greenhouse and climate room experiments and understand how position and number of R gene insertions can affect non-targets in GM events. We also aimed to compare results to baseline differences among three conventional potato varieties varying in resistance to late blight. Aphid development and survival were affected by some GM events in the first generation, though effects disappeared in the second generation. Effects were not dependent on the presence of a marker gene or the insertion of a second resistance gene. Positional effects of gene insertion influenced aphid performance on certain GM events. However, aphid fitness varied considerably more between conventional potato varieties than between Désirée and the GM events. Comparing different GM events to the non-transformed variety is relevant, since unintended effects of insertion can occur. Our protocols can be recommended for in planta risk assessments with aphids. Ecological perspective is gained by selecting several measured endpoints and by comparing the results with a baseline of conventional cultivars.
Assessing environmental impacts of genetically modified plants on non-target organisms : The relevance of in planta studies
Arpaia, Salvatore ; Birch, A.N.E. ; Kiss, Jozsef ; Loon, Joop J.A. van; Messéan, Antoine ; Nuti, Marco ; Perry, Joe N. ; Sweet, Jeremy B. ; Tebbe, Christoph C. - \ 2017
Science of the Total Environment 583 (2017). - ISSN 0048-9697 - p. 123 - 132.
Bacillus thuringiensis - Ecosystem services - Environmental risk assessment - Insect resistance - Insect-plant interactions - Non-target organisms - Risk management
In legal frameworks worldwide, genetically modified plants (GMPs) are subjected to pre-market environmental risk assessment (ERA) with the aim of identifying potential effects on the environment. In the European Union, the EFSA Guidance Document introduces the rationale that GMPs, as well as their newly produced metabolites, represent the potential stressor to be evaluated during ERA. As a consequence, during several phases of ERA for cultivation purposes, it is considered necessary to use whole plants or plant parts in experimental protocols. The importance of in planta studies as a strategy to address impacts of GMPs on non-target organisms is demonstrated, to evaluate both effects due to the intended modification in plant phenotype (e.g. expression of Cry proteins) and effects due to unintended modifications in plant phenotype resulting from the transformation process (e.g. due to somaclonal variations or pleiotropic effects). In planta tests are also necessary for GMPs in which newly expressed metabolites cannot easily be studied in vitro. This paper reviews the scientific literature supporting the choice of in planta studies as a fundamental tool in ERA of GMPs in cultivation dossiers; the evidence indicates they can realistically mimic the ecological relationships occurring in their receiving environments and provide important insights into the biology and sustainable management of GMPs.
Assessing and monitoring impacts of genetically modefied plants on agro-ecosystems: the approach of AMIGA project.
Arpaia, S. ; Messéan, A. ; Birch, N.A. ; Hokkanen, H. ; Härtel, S. ; Loon, J. van; Lovei, G. ; Park, J. ; Spreafico, H. ; Squire, G.R. ; Steffan-Dewenter, I. ; Tebbe, C. ; Voet, H. van der - \ 2014
Atti dell'Accademia Nazionale Italiana di Entomologia Rendiconti 2 (2014)1. - ISSN 0065-0757 - 8 p.
The environmental impacts of genetically modified crops is still a controversial issue in Europe. The overall risk assessment framework has recently been reinforced by the European Food Safety Authority(EFSA) and its implementation requires harmonized and efficient methodologies. The EU-funded research project AMIGA - Assessing and monitoring Impacts of Genetically modified plants on Agro-ecosystems - aims to address this issue, by providing a framework that establishes protection goals and baselines for European agro-ecosystems, improves knowledge on the potential long term environmental effects of genetically modified (GM) plants, tests the efficacy of the EFSA Guidance Document for the Environmental Risk Assessment, explores new strategies for post market monitoring, and provides a systematic analysis of economic aspects of Genetically Modified crops cultivation in the EU. Research focuses on ecological studies in different EU regions, the sustainability of GM crops is estimated by analysing the functional components of the agro-ecosystems and specific experimental protocols are being developed for this scope.
A statistical simulation model for fiels testing of non-target organisms in environmental risk assessment of genetically modified plants
Goedhart, P.W. ; Voet, H. van der; Baldacchino, F. ; Arpaia, S. - \ 2014
Ecology and Evolution 4 (2014)8. - ISSN 2045-7758 - p. 1267 - 1283.
herbicide-tolerant crops - farm-scale evaluations - chrysomelidae)-protected bt corn - zero-inflated poisson - bacillus-thuringiensis - transgenic bt - nontarget arthropods - sample-size - conventional insecticides - lepidoptera-noctuidae
Genetic modification of plants may result in unintended effects causing potentially adverse effects on the environment. A comparative safety assessment is therefore required by authorities, such as the European Food Safety Authority, in which the genetically modified plant is compared with its conventional counterpart. Part of the environmental risk assessment is a comparative field experiment in which the effect on non-target organisms is compared. Statistical analysis of such trials come in two flavors: difference testing and equivalence testing. It is important to know the statistical properties of these, for example, the power to detect environmental change of a given magnitude, before the start of an experiment. Such prospective power analysis can best be studied by means of a statistical simulation model. This paper describes a general framework for simulating data typically encountered in environmental risk assessment of genetically modified plants. The simulation model, available as Supplementary Material, can be used to generate count data having different statistical distributions possibly with excess-zeros. In addition the model employs completely randomized or randomized block experiments, can be used to simulate single or multiple trials across environments, enables genotype by environment interaction by adding random variety effects, and finally includes repeated measures in time following a constant, linear or quadratic pattern in time possibly with some form of autocorrelation. The model also allows to add a set of reference varieties to the GM plants and its comparator to assess the natural variation which can then be used to set limits of concern for equivalence testing. The different count distributions are described in some detail and some examples of how to use the simulation model to study various aspects, including a prospective power analysis, are provided.
Environmental risk assessment of genetically modified organisms: overview of field studies, examples of datasets, statistical models and a simulation tool : report describing ERA datasets and simulation model
Goedhart, Paul W. ; Voet, Hilko van der; Baldacchino, Fernandino ; Arpaia, Salvatore - \ 2013
Wageningen : Wageningen University and Research centre, Plant Research International, Biometris - 51
Feeding behaviour and reproductive biology of Colorado potato beetle adults fed transgenic potatoes expressing the Bacillus thuringiensis Cry3B endotoxin
Arpaia, S. ; Marzo, L. de; Leo, G.M. Di; Santoro, M.E. ; Mennella, G. ; Loon, J.J.A. van - \ 2000
Entomologia Experimentalis et Applicata 95 (2000). - ISSN 0013-8703 - p. 31 - 37.
Transgenic resistance of eggplants to the Colorado potato beetle
Arpaia, S. - \ 1999
Agricultural University. Promotor(en): L.M. Schoonhoven; J.J.A. van Loon. - S.l. : Arpaia - ISBN 9789058080189 - 128
Solanum melongena - Leptinotarsa decemlineata - plaagresistentie - transgene planten - Solanum melongena - Leptinotarsa decemlineata - pest resistance - transgenic plants

The subject of this thesis is the use of transgenic plant resistance as a method to control the Colorado potato beetle, Leptinotarsa decemlineata Say in eggplant. The gene conferring resistance is coding for a Cry3B toxin and it is a synthetic version of a wild-type gene originally obtained from the soil bacterium Bacillus thuringiensis Berl.

Eggplant cultivations are constantly attacked by a number of serious pests (e.g. the fruit and shoot borer, the Colorado potato beetle, soil-borne fungi). In spite of the heavy losses they may cause, breeding for resistance on this crop has been very limited because of the lack of desirable traits in the eggplant genome or sexual incompatibility with the resistant wild related species.

The first chapter reviews Colorado potato beetle biology and its control, with a special emphasis on beetle-eggplant relationships. L. decemlineata has become a major problem for eggplant cultivation and sometimes its control on this crop is even more problematic compared to potato cultivation. The longer life cycle of the plant and the intensive regime under which horticultural crops are cultivated have contributed to the increasing importance of this pest.

In the second chapter, a review of the source of resistant genes available in both the eggplant gene pool and wild Solanum relatives is presented. Considering the genetic basis of resistant traits, the possible strategies for eggplant breeding are discussed with emphasis on approaches based on the integration of classical breeding methods (crosses and selection) with biotechnological ones (anther culture, genetic transformation, protoplast fusion and marker-assisted selection).

In the third chapter, the results of the study in which protein extracts of Escherichia coli expressing the toxin gene from B. thuringiensis were tested for effect on the behavior and development of L. decemlineata larvae using in vitro bioassays are presented. No antifeedant effect due to Cry3B toxin was found, even in concentrations which caused mortality or severely inhibited larval growth.

In the fourth chapter, the production of transgenic eggplants and their evaluation is presented. A modified Bt gene of Bacillus thuringiensis var. Tolworthi, encoding a coleopteran insect-specific Cry3B toxin, was transferred via Agrobacterium tumefaciens to the female parent of the commercial F1 hybrid 'Rimina' eggplant (released by the Istituto Sperimentale per l'Orticoltura). A large number of transgenic plants were regenerated and tested by PCR and NPTII expression assays. The presence of the Cry3B toxin in leaf extracts was demonstrated by the DAS-ELISA test in 57 (62.3%) transgenic plants which contained a 74 kDa protein cross-reacting with the serum anti-Cry3B toxin. Twenty-three out of 44 S. melongena plants tested by an insect bioassay showed a significant insecticidial activity on neonate larvae of Colorado Potato Beetle (CPB). The Bt transgene and the toxic effect on CPB larvae were transmitted to progenies derived by selfing. Thus, transgenic Bt eggplants may represent a very effective means of CPB pest control.

Transgenic potato clones expressing a Cry3B endotoxin were used to study the trophic interactions between newly emerged Colorado potato beetle adults and these resistant clones (Chapter 5). Adult longevity and fitness were studied for the first 3 weeks after emergence. The reproductive biology of the beetle on highly resistant clones, partly resistant clones and control potato plants was monitored by dissecting females after 7-15 days of feeding and by analyzing the haemolymph's protein content after 3 days of feeding. Feeding behavior on either highly toxin expressing or control plants was monitored individually for 36 beetles feeding on leaf-discs. Beetles feeding on transgenic or control clones as the sole source of food had similar longevity. However egg production was completely inhibited on transgenic plants.

Dissection studies indicated that adult males living on transgenic plants were still able to mate and produce mobile sperms, but the females were impaired in their reproductive ability since ovarioles were not normally developed. An exam of the haemolymph revealed the protein concentration in females living on transgenic plants to be dramatically reduced (about 50% compared to the control). The feeding behavior of Colorado potato beetle adults was not affected by the different food plants. This shows that transgenic potato plants were readily accepted as host plants by the beetles. The implications of these findings for the use of transgenic plants as a means of L. decemlineata control are discussed.

In the sixth chapter the most relevant results of the first year of a field experiment with the transgenic eggplant lines are presented. Two of the 3 transgenic lines used showed a high level of resistance in two separate trials, as indicated by the analyses of L. decemlineata population levels and crop yield. Fruit production was almost doubled in the resistant lines compared to a DR2 untransformed control. Only one transgenic line showed an intermediate level of resistance, giving results more similar to the control under heavy CPB attack, whereas it gave comparable results to the other transgenic lines where natural infestation was milder. No detrimental effects on non-target arthropods (including the chrysomelid beetle Altica spp.) were apparent. Field observations confirmed that Bt-expressing transgenic plants might be able to successfully control Colorado potato beetle infestations in eggplant cultivations, representing a potentially effective and environmentally safe means of pest control.

In chapter 7, the relationships between L. decemlineata egg density and Coleomegillamaculata DeGeer predatory behavior is presented. Despite aggregation in areas of the highest prey density by C.maculata , egg consumption was inversely related to egg mass density at the smallest and the largest spatial scales tested. The experimental data on predation rates in high and low density field treatments, were included in a mathematical model to simulate the impact of natural enemies on the rate of L.decemlineata adaptation to Bt-toxin-expressing transgenic potato plants when Bt-expressing plants are mixed at the plot-to-plot level with normal potato plants. Results showed that C.maculata predatory behavior could decrease the rate at which L.decemlineata adapted to Bt-toxins if plot-to-plot mixed plantings were used.

Finally, a simulation model to predict the possible adaptation of L. decemlineata to the Cry3 toxin expressed in transgenic eggplant is presented (Chapter 8). The use of mixed fields of transgenic and susceptible isolines at a 90:10 ratio has been simulated. Beetle movement, which is a fundamental parameter when studying plant mixtures, has been addressed with a 'two-stage' hypothesis. The biological and genetic characteristics of the beetles have been set to specifically address their possible interactions with resistant eggplant. The role of gene dominance, migration, and fitness costs associated with the resistant genotype have been examined. Using the hypothesis of partial dominance of the resistant gene, only a high level of migration (very likely, in most agricultural areas) or a considerable reduction of the fitness of resistant beetles, associated with the change in their genome, can guarantee a long-lasting efficacy of the germplasm. The simulations clearly indicate that the effect of resistance in transgenic clones expressing Bacillus thuringiensis -derived toxins can be optimized only in accordance with opportune agricultural practices.

Effects of azadirachtin after systemic uptake into Brassica oleracea on larvae of Pieris brassicae.
Arpaia, S. ; Loon, J.J.A. van - \ 1993
Entomologia Experimentalis et Applicata 66 (1993). - ISSN 0013-8703 - p. 39 - 45.
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