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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    Ecological illiteracy can deepen farmers' pesticide dependency
    Wyckhuys, K.A.G. ; Heong, K.L. ; Sanchez-Bayo, F. ; Bianchi, F.J.J.A. ; Lundgren, J.G. ; Bentley, J.W. - \ 2019
    In: Environmental Research Letters Environmental Research Letters 14 (2019)9. - ISSN 1748-9318IOP Publishing (Environmental Research Letters )

    Nearly 2.5 billion smallholders cultivate the world's arable land, strategically positioned to tackle multiple Anthropocene challenges. When consciously adopting ecologically-based pest management practices, they can improve resource use efficiency, slow biodiversity loss, curtail environmental pollution and safeguard human health. Yet, the effective implementation of knowledge-intensive management practices requires underlying ecological concepts to be well-understood. Here, drawing upon published social science research spanning 1910-2016, we illuminate deficiencies in the world's farmers' ecological literacy and in their valuation of insect-mediated ecosystem services. Though tribal people and indigenous folk possess sophisticated knowledge of insects that occur within farm settings, contemporary farmers on average know a mere 1.9-2.3 pestiferous herbivores and 0.5-0.9 pest-killing organisms (out of a respective 8 and 3 taxa) in a particular crop or cropping system. Ecosystem services such as biological pest control are annually worth hundreds of dollars ha-1 but remain unknown to nearly 70% of farmers globally. Also, agricultural systems with deficient ecological literacy tend to foster a greater dependency upon chemically-synthesized pesticides. If this 'cognitive handicap' can be remediated, farmers could become agro-biodiversity stewards and champions in redressing multiple aspects of global environmental change.

    Letter to the editor: Science-Policy Interface: Beyond Assessments
    Hulme, M. ; Mahony, M. ; Beck, S. ; Görg, C. ; Hansjürgens, B. ; Hauck, J. ; Nesshöver, C. ; Paulsch, A. ; Vandewalle, M. ; Wittmer, H. ; Böschen, S. ; Bridgewater, P. ; Diaw, M.C. ; Fabre, P. ; Figueroa, A. ; Heong, K.L. ; Korn, H. ; Leemans, R. ; Lövbrand, E. ; Hamid, M.N. ; Monfreda, C. ; Pielke, R. ; Settele, J. ; Winter, M. de; Vadrot, A.B.M. ; Hove, S. van den; Sluijs, J.P. van der - \ 2011
    Science 333 (2011)6043. - ISSN 0036-8075 - p. 697 - 698.
    In recognition of our inability to halt damaging ecosystem change (1–4), the United Nations Environment Programme (UNEP) was asked in December 2010 to convene a meeting “to determine modalities and institutional arrangements” of a new assessment body, akin to the Intergovernmental Panel on Climate Change (IPCC), to track causes and consequences of anthropogenic ecosystem change (5). The “blueprint” for this body, the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES), lies in recommendations of an intergovernmental conference held in the Republic of Korea in June 2010: the Busan outcome (6). But it is a blueprint for governance rather than science. Using the experience from past assessments of global biodiversity and ecosystem services change (1, 7, 8) and from the IPCC (9–11), we ask what the policy-oriented charges in the Busan outcome imply for the science of the assessment process
    Consequences of technologies and production diversification for the economic and environmental performance of rice-based farming systems in East and Southeast Asia
    Hengsdijk, H. ; Berg, M.M. van den; Roetter, R.P. ; Guanghuo, W. ; Wolf, J. ; Lu Changhe, ; Keulen, H. van - \ 2005
    In: Rice is life: scientific perspectives for the 21st century: World Rice Research Conference, Tokyo, 4-7 November 2004. - Tokyo : Japan International Research Center for Agricultural Science - p. 422 - 425.
    Effect of prey and predictor density on prediction of rice leaffolder eggs by the cricket Metioche vittaticollis.
    Kraker, J. de; Huis, A. van; Lenteren, J.C. van; Heong, K.L. ; Rabbinge, R. - \ 2001
    Biocontrol Science and Technology 11 (2001). - ISSN 0958-3157 - p. 69 - 82.
    Cage experiments were conducted to quantify the predation rate of the cricket Metioche vittaticollis (Sta˚l) on the eggs of rice leaffolder Marasmia patnalis Bradley. Egg predation by adult females was measured in response to changes in egg density, predator density and leaf area per cage. The number of eggs consumed per predator increased with egg density, without reaching a plateau. The predation rate decreased with increasing leaf area. The functional response could be adequately described with a linear Type I model, with the effect of leaf area included. This type of response to leaffolder egg density means that predation was not limited by prey handling time or satiation, but by the search rate. The search rate is here interpreted as the leaf area effectively searched for leaffolder eggs by a single predator in one day. Estimated search rates averaged 0.13 m2 day -1 for M. vittaticollis females. The search rate of the predators increased with prey density, but a model describing a density dependent search rate explained only 3 f the total variation in search rate. Increasing predator density per cage led to a decrease in the per capita egg predation rate when predator density was more than two per m2 leaf area. Interference might thus reduce the potential to enhance leaffolder egg predation by conservation or augmentation of predatory cricket populations
    Impact of nitrogenous-fertilization on the population dynamics and natural control of rice leaffolders (Lep.: Pyralidae)
    Kraker, J. de; Rabbinge, R. ; Huis, A. van; Lenteren, J.C. van; Heong, K.L. - \ 2000
    International Journal of Pest Management 46 (2000)3. - ISSN 0967-0874 - p. 225 - 235.
    The effect of nitrogenous-fertilization on the population dynamics and natural control of rice leaffolders was studied in an irrigated rice area in the Philippines. Nitrogen was applied at three levels (0, 75 and 150 kg N ha-1), and its impact on crop growth and yield, arthropod abundance, and rates of leaffolder parasitism and survival was assessed with weekly samples. Rice plants were taller and had a higher leaf nitrogen content with increasing levels of nitrogenous fertilization, but grain yield was highest at the medium nitrogen level. Herbivores, predators, and parasitoids increased in abundance with nitrogenous-fertilization level. The average density of rice leaffolder larvae at the highest nitrogen level was eight times the density at zero nitrogen level, and the peak percentage injured leaves increased from 5 to 35&Eth;The strong increase in larval density was due to the positive effect of nitrogenous-fertilization on egg recruitment and survival of medium-sized larvae. The percentage parasitism of eggs and larvae was not affected by nitrogenous-fertilization. The increase in survival of medium-sized larvae with nitrogen levels was associated with lower predator to leaffolder ratios. The strong effect of nitrogenous-fertilization in the present small-scale experiment was attributed mainly to allowing the moths an oviposition choice between plots with different application levels of nitrogen. Therefore it is hypothesized that the effect of increasing nitrogenous-fertilization level on leaffolder larval densities will be less pronounced when implemented over a large area.
    Identity and relative importance of egg predators of rice leaffolders (Lepidoptera:Pyralidae.)
    Kraker, J. de; Huis, A. van; Lenteren, J.C. van; Heong, K.L. ; Rabbinge, R. - \ 2000
    Biological Control 19 (2000)3. - ISSN 1049-9644 - p. 215 - 222.
    Field andlaboratory studies on predation of rice leaffolder eggs (i.e., Cnaphalocrocis medinalis (Guenée) and Marasmia patnalis Bradley) were conducted to identify major predator species. Direct observations of predation on field-exposed eggs showed that in two seasons Metioche vittaticollis (Stål) and Anaxipha longipennis (Serville) were the major predators of leaffolder eggs. Together these crickets took the largest part of all eggs consumed during observation (92€and had the highest ratio of visits with predation to their total observed visits to plants with leaffolder eggs. Furthermore, the activity pattern of the crickets matched best the daily pattern of egg disappearance, and the seasonal trends in their observed visits correlated best with the seasonal trends in egg disappearance. Minor predators feeding on field-exposed rice leaffolder eggs were Ophionea nigrofasciata Schmidt-Goebel, Micraspis sp., and Conocephalus longipennis (de Haan). The latter species was the most commonly observed egg predator, but had a negligible share in the total predation. In petri dish tests the consumption of leaffolder eggs by the predatory crickets M. vittaticollis and A. longipennis was far greater than that of four other predators. Female cricket adults consumed at least 80 eggs per day, and all individuals accepted leaffolder eggs as food. According to daily egg consumption and acceptance rates, the predators ranked as follows: M. vittaticollis, A. longipennis > Micraspis sp. > O. nigrofasciata > Paederus fuscipes Curtis, C. longipennis. Predator ranking according to the ratio of visits with predation to total visits in the field was identical to the ranking based on the egg consumption tests. Due to their large predation potential, predatory crickets will probably play an important role in leaffolder egg predation, even when their densities are low compared to those of other predator species.
    Population dynamics of rice leaffolders(Lepidoptera: Pyralidae) and their natural enemies in irrigated rice in the Philippines
    Kraker, J. de; Huis, A. van; Heong, K.L. ; Lenteren, J.C. van; Rabbinge, R. - \ 1999
    Bulletin of Entomological Research 89 (1999)5. - ISSN 0007-4853 - p. 411 - 421.
    Populations of rice leaffolders and their natural enemies were studied in eight crops of irrigated rice in Laguna Province, the Philippines. The rice leaffolder complex consisted of three species: Cnaphalocrocis medinalis (Guenée), Marasmia patnalis Bradley and M. exigua Butler. Leaffolder population dynamics were characterized by an egg peak at maximum tillering and a broad larval peak around booting stage. Peak densities ranged from 0.2 to 2.0 larvae per hill. Most larvae originated from immigrant moths and there was no substantial second generation. The seasonal percentage egg parasitism by Trichogramma sp. ranged from 0 to 27°and percentage larval parasitism from 14 to 56ÐThe braconid Macrocentrus philippinensis Ashmead was the most commonly reared larval parasitoid. Forty natural enemy taxa that may attack rice leaffolders were identified from suction and sweepnet samples: 24 predator taxa and 16 parasitoid taxa. The estimated survival rates from leaffolder egg to larval stages and between larval stages showed large variation between rice crops, but were not clearly correlated with observed levels of parasitism, natural enemy abundance, or natural enemy to leaffolder ratios. It is suggested that the generally low densities of rice leaffolders in Philippine transplanted rice are caused by their ovipositional preference for crops at the maximum tillering stage, allowing for only one generation, and by high immature mortality caused by the abundant and diverse complex of natural enemies.
    Egg mortality of rice leaffolders Cnaphalocrocis medinalis and Marasmia patnalis in irrigated rice fields
    Kraker, J. de; Huis, A. van; Lenteren, J.C. van; Heong, K.L. ; Rabbinge, R. - \ 1999
    Biocontrol Science and Technology 44 (1999)4. - ISSN 0958-3157 - p. 451 - 473.
    Egg mortality of rice leaf folders Cnaphalocrocis medinalisand Marasmia patnalis was studied in unsprayed irrigated rice fields in Laguna Province, the Philippines. Mortality was assessed by field exposure of laboratory-laid eggs for two days and by monitoring of field-laid eggs. Egg disappearance, the major mortality factor, was low in the first four weeks after transplanting and then increased. Egg parasitism by Trichogrammajaponicum was highest at the start of the crop and decreased to a low level towards crop maturity. Non-hatching of eggs was of minor importance. Over the total duration of the egg stage, the average disappearance of exposed laboratory-laid eggs was40%, and of field-laid eggs 46%. Egg mortality due to parasitism averaged 15% and 18%, respectively. The potential impact of egg parasitism is probably partly obscured by the disappearance of parasitized eggs. Mortality rates were highly variable between egg cohorts, but with multiple regression analysis several factors were identified that statistically explained a significant part of this variation. The results suggest that the predatory crickets Metiochevittaticollis and Anaxipha longipennis play a major role in egg disappearance, and that egg parasitism is positively dependent on the overall density of host eggs of Trichogramma in the field.
    Opportunities for using systems approaches in pest management.
    Rossing, W.A.H. ; Heong, K.L. - \ 1997
    Field Crops Research 51 (1997). - ISSN 0378-4290 - p. 83 - 100.
    Pest problems are complex and a systems view contributes to understanding their causes and assessing possible solutions. Systems approaches provide a framework for systematic analysis, synthesis and design of agricultural systems at different levels of aggregation. In systems research, the real world is divided into systems, the essence of which is captured in models. The choice of system boundaries is determined by the objectives of the study. Explanatory simulation models are based on the distinction between the process level, or explanatory level, and the system level, or level to be explained. In the course of systems research, three phases are distinguished, each with a different product: problem identification results in a conceptual model, increasing production ecological insight results in a comprehensive model, and systems design results in options and their relation to objectives of management. Various qualitative and quantitative tools are available in each of the phases. Opportunities and constraints for using systems approaches in all three phases are discussed, using illustrations at the crop, farm and regional levels.
    Linked pest-crop models under global change.
    Teng, P.S. ; Heong, K.L. ; Kropff, M.J. ; Nutter, F.W. ; Suthurst, R.W. - \ 1996
    In: Global change and terrestrial ecosystems / Walker, B.H., Steffen, W.L., - p. 291 - 316.
    Opportunities for using systems approaches in pest management.
    Rossing, W.A.H. ; Heong, K.L. - \ 1995
    In: Abstract 2nd Int. Symp. Systems Approaches for Agricultural Development (SAAD) and Workshop on Applications of Simulation and Systems Analysis for Rice Production (SARP), IRRI, Los Baños, Philippines - p. 126 - 126.
    Mechanisms of damage by stem borer, bacterial leaf blight and sheath blight, and their effects on rice yield : proceedings of workshops in Khon Kaen, Thailand, 3 - 5 August 1992, and Cuttack, India, 3 - 5 March 1993
    Rossing, W.A.H. ; Rubia, E.G. ; Heong, K.L. - \ 1993
    Wageningen [etc.] : DLO-Centre for Agrobiological Research [etc.] (SARP research proceedings ) - ISBN 9789073384194 - 137
    computer simulation - crop damage - crop losses - oryza sativa - parasites - rice - simulation - simulation models - yield losses - computersimulatie - oogstschade - gewasverliezen - oryza sativa - parasieten - rijst - simulatie - simulatiemodellen - oogstverliezen
    Mechanisms of damage by stem borer, bacterial leaf blight and sheath blight, and their effects on rice yield.
    Rossing, W.A.H. ; Rubia, E.G. ; Heong, K.L. ; Keerati-Kasikorn, M. ; Reddy, P.R. - \ 1993
    Unknown Publisher (SARP Research Proceedings ) - 137 p.
    Damage by stem borer, bacterial leaf blight and sheath blight in rice: conceptual models.
    Heong, K.L. ; Rossing, W.A.H. - \ 1993
    In: Mechanisms of damage by stem borer, bacterial leaf blight and sheath blight, and their effects on rice yield / Rossing, W.A.H., - p. 55 - 60.
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