Dr Ir Wopke van der Werf

•           
  Associate professor; Quantitative crop ecology: Ecology and management of pests, diseases and weeds; Biological control; spatial population modelling and sampling
• Teaching subjects
• Research projects
• Personal information
• Publications

Courses taught

• Population & Systems Ecology (CWE-22306)
• Interactive Mathematical Ecology (CWE-50806)
• Biology and Management of Plant Pathogens, Insects and Weeds II (ENT-20306)
• Agroforestry (guest lecture; FEM-22803)

Research projects

• Resource use efficiency of cotton-wheat based cropping systems in China
• Population dynamics
• Weed seed removal in relation to spatial dynamics of seed predators
• Spatial dynamics and site-specific management of weeds
• Competitive fitness and persistence of wildtype and genetically modified baculoviruses
• Experimental evolution: A novel approach to understand baculovirus diversity
• Bio-economic analysis of brownrot/ringrot abatement
• Landscape composition, biodiversity and ecosystem functioning
• Chain-risk analysis and monitoring of plant diseases
• Quantification of the risk of infection by Phytophthora infestans

Recently Finished Projects

• Silvo-arable Agroforestry for Europe (SAFE)
• BIOSPORSUPPRESS: Biological control of air-borne necrotrophic plant pathogens by suppression of spore production
• Quantification of infection pressure from distant sources of Phytophthora infestans and its consequences for the fungicide requirement in potato crops, using a regional model of spore dispersal
• Modelling the control of Helicoverpa armigera with polyhedroviruses in cotton fields
• Designing improved desert locust survey and control strategies, using scenario studies
• Biological control of seed beetles (Bruchidae) in stored cowpea (Vigna unguiculata) in West Africa, using egg para-sitoids of the genus Uscana
• Reduced-input weed management options for reduced-tillage systems for smallholder farmers in Zimbabwe

Possibilities for MSc thesis

• Model evaluation of weather relationships determining spore production and infection risk in Phytophthora infestans
• Life cycle parameters of weeds and vulnerability of weeds to seed predation
• Weed seed losses and the impact on weed population dynamics
• Ecology and management of locusts
• Population biology of the granivorous groundbeetle, Harpalus rufipes
• Biodiversity and the natural control of pests and weeds
• IPM and system analysis
• Metapopulation dynamics and plant disease

Personal information
BSc, Wageningen University, Crop Protection
MSc, Wageningen University, Entomology, Phytopathology, Theoretical Production Ecology & Mathematical Statistics
PhD, Wageningen University, Virology & Theoretical Production Ecology

My research aims at developing insights and tools for an effective and ecologically sound crop protection against pests, diseaes and weeds. I conduct research projects on biological control of insects and fungi, the modelling of (spatial) population processes and the use of models to analyse and design crop protection systems.
Many projects are conducted in the framework of international cooperation, which is effective as well as fun. Recently started projects focus on biodiversity and the role of landscape and intercropping in biological control.
My teaching involves BSc level courses in population ecology (CWE-20806), Biodiversity (CWE-10806) and Biology and Management of Plant Pathogens, Insects and Weeds II (ENT-20306), as well as ad hoc summer schools and post doctoral courses.

Publications (selection)

2008

• van Huis, A., G. Woldewahid, K. Toleubayev & W. van der Werf, 2008. Relationships between food quality and fitness in the desert locust, Schistocerca gregaria, and its distribution over habitats on the Red Sea coastal plain of Sudan. Entomologia Experimentalis & Applicata 127, 144-156.
• Zwart, M.P., M.M. van Oers, J.S. Cory, J.W.M. van Lent, W. van der Werf & J.M. Vlak. A real-time PCR-based assay for quantifying genotype frequencies of Autographa californica Multiple Nucleopolyhedrovirus in mixed populations. Journal of Virological Methods 148, 146-154.
• Surkov, I.V., W. van der Werf, O. van Kooten & A.G.J.M. Oude Lansink, 2008. Modeling the rejection probability in plant imports. Phytopathology 98, 728-735.
• Zhang, L.Z., W. van der Werf, L. Bastiaans, S. Zhang, B. Li & J.H.J. Spiertz, 2008. Light interception and radiation use efficiency in relay intercrops of wheat and cotton. Field Crops Research 107, 29-42.
• Zhang, L.Z., W. van der Werf, S. Zhang, B. Li & J.H.J. Spiertz, 2008. Temperature-mediated developmental delay may limit yield of cotton in relay intercrops with wheat. Field Crops Research 106, 258-268.
• Zhang, L.Z., J.H.J. Spiertz, S. Zhang, B. Li and W. van der Werf, 2008. Nitrogen economy in relay intercropping systems of wheat and cotton. Plant and Soil 303, 55-68.
• Breukers, A., M. Mourits, W. van der Werf & A.G.J.M. Oude Lansink, 2008. Costs and benefits of controlling quarantine diseases; a bioeconomic modelling approach. European Review of Agricultural Economics 38, 1-13.
• Saska, P., W. van der Werf, E. de Vries & P.R. Westerman, 2008. Spatial and temporal patterns of carabid activity density in cereals do not explain levels of predation on weed seeds. Bulletin of Entomological Research 98, 169 – 181.

2007

• Bianchi, F.J.J.A., W. van der Werf & A. Honĕk, 2007. Changes in agricultural land use can explain population decline in a ladybeetle species in the Czech Republic; evidence from a process-based spatially explicit model. Landscape Ecology 22, 1541-1554.

• Costamagna, A.C., W. van der Werf, F.J.J.A. Bianchi & D.A. Landis. An exponential growth model with decreasing r captures bottom-up effects on the population growth of Aphis glycines Matsumura (Hemiptera: Aphididae). Agricultural & Forest Entomology 9, 297-305.

• Surkov, I.V., W. van der Werf, O. van Kooten & A.G.J.M. Oude Lansink, 2007. Interceptions of harmful organisms during import inspections of cut flowers in the Netherlands: an empirical and theoretical analysis of the ‘reduced checks’ system. EPPO Bulletin 37, 395-403.
• Keesman, K.J., W. van der Werf & H. van Keulen. Production Ecology of Agroforestry Systems: a minimal mechanistic model and analytical derivation of the land equivalent ratio. Mathematical BioSciences 209, 608-623.
• Zhang, L., W. van der Werf, S. Zhang, B. Li & J.H.J. Spiertz, 2007. Growth, yield and quality of wheat and cotton in relay strip intercropping systems. Field Crops Research 103, 178-188.
• Heijting, S., W. van der Werf, A. Stein & M.J. Kropff, 2007. Are weed patches stable in location? Application of an explicitly two-dimensional methodology. Weed Research 47, 381-395.
• Heijting, S., W. van der Werf, W. Kruijer & A. Stein, 2007. Testing the spatial significance of weed patterns in an arable land using Mead's test. Weed Research 47, 396-405.
• Palma, J., A.R. Graves, P.J. Burgess, W. van der Werf & F. Herzog, 2007. Integrating environmental and economic performance to assess modern silvoarable agroforestry in Europe. Ecological Economics 63, 759–767.
• Breukers, A., W. van der Werf, J.P.C. Kleijnen, M. Mourits & A.G.J.M. Oude Lansink. Options for cost-effective control of a quarantine disease: a quantitative exploration using “design of experiments” methodology and bio-economic modeling. Phytopathology 97, 945-957.
• Saska, P., M. Vodde, Th. Heijerman, P.R. Westerman & W. van der Werf, 2007. The significance of a grassy field boundary for the spatial distribution of carabid activity-density and diversity within two organic cereal fields. Agriculture, Ecosystems & Environment, 122, 427–434.
• Westerman, P.R., A. van Ast, T.J. Stomph & W. van der Werf, 2007. Long-term management of the parasitic weed Striga hermonthica; Strategy evaluation with a population model. Crop Protection 26, 219-227.
• Woldewahid, Gebremedhin, Wopke van der Werf, Karle Sykora, Tsedeke Abate, Bashir Mostofa & Arnold van Huis, 2007. Description of plant communities on the Red Sea coastal plain of Sudan. Journal of Arid Environments 68, 113-131.
• van der Werf, Wopke, Karel Keesman, Paul Burgess, Anil Graves, David Pilbeam, L.D. Incoll, Klaas Metselaar, Martina Mayus, Roel Stappers, Herman van Keulen, João Palma & Christian Dupraz, 2007. Yield-SAFE: a parameter-sparse process-based dynamic model for predicting resource capture, growth and production in agroforestry systems. Ecological Engineering 29, 419-433.
• Graves, A.R., P.J. Burgess, J.H.N. Palma, F. Herzog, G. Moreno, M. Bertomeu, C. Dupraz, F. Liagre, K.J. Keesman, W. van der Werf, A. Koeffeman de Nooy & J.P. van den Briel, 2007. The development and application of bio-economic modelling for silvoarable systems in Europe. Ecological Engineering 29, 434-449.

2006

• Breukers, Annemarie, Dirk L. Kettenis, Monique Mourits, Wopke van der Werf & Alfons Oude Lansink, 2006. Individual-based models in the analysis of disease transmission in plant production chains: an application to potato brown rot.  Agricultural Systems 90, 112-131.
• Sun, X.,  W. van der Werf, F.J.J.A. Bianchi, Z. Hu & J.M. Vlak, 2006. Modelling the behaviour of wild-type and genetically modified baculoviruses in the Helicoverpa armigera - cotton system. Ecological Modelling 198, 387-398.
• Zhang, L.Z., B.G. Li, G.T. Yan, W. van der Werf, J.H.J. Spiertz & S.P. Zhang, 2006. Genotype and planting density effects on rooting traits and yield in cotton (Gossypium hirsutum L.). Journal of Integrative Plant Biology 48, 1287-1293.

2005

• Breukers, A., Th. Hagenaars, W. van der Werf & A.G.J.M. Oude-Lansink, 2005. Brown rot modelling in the Dutch potato production chain. Nonlinear Analysis: Real World Applications 6, 797-815.
• Kessel, G.J.T., J. Köhl, J. Powell, R. Rabbinge & W. van der Werf, 2005. Modelling spatial characteristics in the biocontrol of fungi at leaf level: competitive substrate colonization by Botrytis cinerea and the saprophytic antagonist Ulocladium atrum. Phytopathology, 95, 439-448.
• Marino, P.C., P.R. Westerman, C. Pinkert & W. van der Werf, 2005. Influence of seed density and aggregation on post-dispersal weed seed predation in cereal fields. Agriculture, Ecosystems and Environment 106, 17-25.
• Powell, J.A., I. Slapnicar & W. van der Werf, 2005. Epidemic Spread of a Lesion-Forming Plant Pathogen – Analysis of a Mechanistic Model with Infinite Age Structure. Linear Algebra and its Applications 398, 117–140.
• Skelsey, P., W.A.H. Rossing, G.J.T. Kessel, J.A. Powell & W. van der Werf, 2005. Influence of Host Diversity on Development of Epidemics: An Evaluation and Elaboration of Mixture Theory. Phytopathology 95, 328-338.
• Stolk, C., M.N. Ghimire, S. Souguié, W. van der Werf & A. van Huis, 2005. Host finding by Uscana lariophaga (Hymenoptera: Trichogrammatidae) in stored cowpea: the effect of distance, time interval, host patch size and spatial orientation. Bulletin of Entomological Research 95, 231-241.
• Sun, X., X. Sun, B. Bai, W. van der Werf, J.M. Vlak and Z. Hu, 2005. Production of polyhedral inclusion bodies from Helicoverpa armigera larvae infected with wild-type and recombinant HaSNPV. Biocontrol Science and Technology 15(4), 353-366.
• van der Werf, W., G. Woldewahid, A. van Huis, M. Butrous & K. Sykora. Plant communities can predict the distribution of solitarious desert locust Schistocerca gregaria Forsk. Journal of Applied Ecology 42, 989-997.
• Zhou, M., X. Sun, X. Sun, J.M. Vlak, Z. Hu & W. van der Werf, 2005. Horizontal and Vertical Transmission of Wild-type and Recombinant Helicoverpa armigera Single-nucleocapsid Nucleopolyhedrovirus. Journal of Invertebrate Pathology 89, 165-175.

2004

• Adjei-Nsiah, S., C. Leeuwis, K.E. Giller, O. Sakyi-Dawson, J. Cobbina, T.W. Kuyper, M. Abekoe & W. Van der Werf, 2004. Land tenure and differential soil fertility management practices among native and migrant farmers in Wenchi, Ghana: Implications for interdisciplinary action research. NJAS – Wageningen Journal of Life Sciences 52, 331-348.
• Bianchi, F.J.J.A. & W. van der Werf, 2004. Model evaluation of the function of prey in non-crop habitats for biological control by ladybeetles in agricultural landscapes. Ecological modelling, 171(1), 177–193.
• Sun, X., W. van der Werf, J.M. Vlak & Z. Hu, 2004. Field inactivation of wild-type and genetically modified Helicoverpa armigera single nucleocapsid nucleopolyhedrovirus in cotton. Biocontrol Science and Technology 14(2), 185-192.
• Sun, X., H. Wang, X. Sun, X. Chen, C. Peng, D. Pan, J.A. Jehle, W. van der Werf, J.M. Vlak and Z. Hu, 2004. Biological activity and field efficacy of a genetically modified Helicoverpa armigera single-nucleocapsid nucleopolyhedrovirus expressing an insect-selective toxin from a chimeric promoter. Biological Control 29, 124–137.
• Woldewahid, G., W. van der Werf, A. van Huis & A. Stein, 2004. Spatial distribution of populations of solitarious adult desert locust (Schistocerca gregaria Forsk.) on the coastal plain of Sudan. Agricultural and Forest Entomology 6, 181-191.

2003

• Bianchi, F.J.J.A. & W. van der Werf, 2003. The Effect of the Area and Configuration of Hibernation Sites on the Control of Aphids by Coccinella septempunctata (Coleoptera: Coccinellidae) in Agricultural Landscapes: A Simulation Study. Environmental Entomology 32(6), 1290-1304.
• Westerman, P.R., J.S. Wes, M.J. Kropff & W. van der Werf, 2003. Annual weed seed losses due to predation in organic cereal fields. Journal of Applied Ecology  40, 824-836.
• Westerman, P.R., A. Hofman, L.E.M. Vet & W. van der Werf, 2003. Relative importance of vertebrates and invertebrates in epigaeic weed seed predation in organic cereal fields. Agriculture, Ecosystems and Environment 95, 417–425.
• Xia, J.Y.,  R. Rabbinge & W. van der Werf, 2003. Multi Stage Functional Responses in a Ladybeetle-Aphid System; Scaling up from the Laboratory to the Field. Environmental Entomology 32(1), 151-162.