- Carolien Kroeze (1)
- Hans Kros (1)
- P.A. Leffelaar (1)
- Merel M. Wal Van der (1)
- M.C.M. Mourits (1)
- P.A.J. Oort van (1)
- R. Rabbinge (1)
- Caroline Salm van der (1)
- M.M. Siko (1)
- Pieter Valkering (1)
- Wim Vries de (1)
- J. Wang (1)
- E. Wera (1)
- W. Werf van der (1)
- J.Y. Xia (1)
Development of a stage-structured process-based predator–prey model to analyse biological control of cotton aphid, Aphis gossypii, by the sevenspot ladybeetle, Coccinella septempunctata, in cotton
Xia, J.Y. ; Wang, J. ; Cui, J.J. ; Leffelaar, P.A. ; Rabbinge, R. ; Werf, W. van der - \ 2018
Ecological Complexity 33 (2018). - ISSN 1476-945X - p. 11 - 30.
Cage studies - Field experiments - Laboratory - predator–prey dynamics - Simulation model
Agricultural system diversification is well known to affect the population dynamics of crop pests, but predator–prey dynamics in crop systems are difficult to analyse due to interactions between multiple life stages of predator and prey, the modulating effect of temperature, the actions of additional predators, and the open nature of the system, with immigration and emigration of both predators and prey. To better understand and characterize the predator–prey system dynamics under field conditions, we developed a detailed process-based simulation model for the stage structured population interaction between cotton aphid, Aphis gossypii, and its main natural enemy, the sevenspot ladybeetle Coccinella septempunctata. The model includes interactions between all insects stages as affected by temperature and host growth, and was parameterized based on detailed data collection in the laboratory and the field. The model was tested with independent data. Simulations show that the initial predator–prey ratio, as affected by immigration rates of the aphid and the predators into the crop, is the key factor for biological control. The model is a useful tool for scenario assessments on the effects of crop diversification on pest-natural enemy dynamics.
Phenology, sterility and inheritance of two environment genic male sterile (EGMS) lines for hybrid rice
El-Namaky, R. ; Oort, P.A.J. van - \ 2017
Rice 10 (2017). - ISSN 1939-8425 - 17 p.
Environment-conditioned genic male sterility (EGMS) - Inheritance - Simulation model
Background: There is still limited quantitative understanding of how environmental factors affect sterility of Environment-conditioned genic male sterility (EGMS) lines. A model was developed for this purpose and tested based on experimental data from Ndiaye (Senegal) in 2013-2015. For the two EGMS lines tested here, it was not clear if one or more recessive gene(s) were causing male sterility. This was tested by studying sterility segregation of the F2 populations. Results: Daylength (photoperiod) and minimum temperatures during the period from panicle initiation to flowering had significant effects on male sterility. Results clearly showed that only one recessive gene was involved in causing male sterility. The model was applied to determine the set of sowing dates of two different EGMS lines such that both would flower at the same time the pollen would be completely sterile. In the same time the local popular variety (Sahel 108, the male pollen donor) being sufficiently fertile to produce the hybrid seeds. The model was applied to investigate the viability of the two line breeding system in the same location with climate change (+2oC) and in two other potential locations: in M’Be in Ivory Coast and in the Nile delta in Egypt. Conclusions: Apart from giving new insights in the relation between environment and EGMS, this study shows that these insights can be used to assess safe sowing windows and assess the suitability of sterility and fertility period of different environments for a two line hybrid rice production system.
Cost-Effectiveness of Mass Dog Vaccination Campaigns against Rabies in Flores Island, Indonesia
Wera, E. ; Mourits, M.C.M. ; Siko, M.M. ; Hogeveen, H. - \ 2017
Transboundary and Emerging Diseases 64 (2017)6. - ISSN 1865-1674 - p. 1918 - 1928.
Cost-effectiveness analysis - Dog - Flores Island - Rabies - Simulation model - Vaccination strategies
A dynamic deterministic simulation model was developed to determine the cost-effectiveness of different mass dog vaccination strategies against rabies in a dog population representative of a typical village on Flores Island. Cost-effectiveness was measured as public cost per averted dog-rabies case. Simulations started with the introduction of one infectious dog into a susceptible dog population of 399 dogs and subsequently ran for a period of 10 years. The base scenario represented a situation without any control intervention. Evaluated vaccination strategies were as follows: annual vaccination campaigns with short-acting vaccine (immunity duration of 52 weeks) (AV_52), annual campaigns with long-acting vaccine (immunity duration of 156 weeks) (AV_156), biannual campaigns with short-acting vaccine (BV_52) and once-in-2-years campaigns with long-acting vaccine (O2V_156). The effectiveness of the vaccination strategies was simulated for vaccination coverages of 50% and 70%. Cumulative results were reported for the 10-year simulation period. The base scenario resulted in three epidemic waves, with a total of 1274 dog-rabies cases. The public cost of applying AV_52 at a coverage of 50% was US$5342 for a village. This strategy was unfavourable compared to other strategies, as it was costly and ineffective in controlling the epidemic. The costs of AV_52 at a coverage of 70% and AV_156 at a coverage of 70% were, respectively, US$3646 and US$3716, equivalent to US$3.00 and US$3.17 per averted dog-rabies case. Increasing the coverage of AV_156 from 50% to 70% reduced the number of cases by 7% and reduced the cost by US$1452, resulting in a cost-effectiveness ratio of US$1.81 per averted dog-rabies case. This simulation model provides an effective tool to explore the public cost-effectiveness of mass dog vaccination strategies in Flores Island. Insights obtained from the simulation results are useful for animal health authorities to support decision-making in rabies-endemic areas, such as Flores Island.
Evaluation of different approaches to describe the sorption and desorption of phosphorus in soils on experimental data
Salm, Caroline van der; Kros, Hans ; Vries, Wim de - \ 2016
Science of the Total Environment 571 (2016). - ISSN 0048-9697 - p. 292 - 306.
(De)sorption - Field experiments - Model performance - Phosphate - Pot experiments - Simulation model
Phosphorus is an essential element to enhance the needed increase in crop production in the forthcoming century. On the other hand environmental losses of phosphorus cause eutrophication of surface waters. Both problems call for reliable models to predict the behaviour of phosphorus in agricultural soils. In this study the performances of five different sorption approaches were evaluated. The ultimate aim was to identify the most suitable concept for large scale predictions of P dynamics in soils, in terms of a high comparability between observations and predictions with a minimum amount of input data. The model results were compared with unique data from long term (10–15 years) experimental field studies of grassland including situations with P mining, equilibrium P fertilization and P surpluses and a pot experiment with P mining. The model performance was evaluated while using site specific constants and generic constants for adsorption and desorption. Three rate limited models (DPPS, INITIATOR and ANIMO) showed good performance when site specific constants were used but the performance of the equilibrium model (NEWS-Dynamic) was reasonably comparable. Model performance was better for experiments with a P surplus than for P mining and was also better for sandy soils as compared to clay and peat soils. However, long term desorption rates had to be calibrated for each application rate. The performance of all models declined when generic data were used. We conclude that none of the included models properly describe what happens when the soil changes its P status, considering that parameterization needs to be treatment-specific to obtain reliable predictions. Considering this flaw, models of intermediate complexity, including both equilibrium and rate limited sorption, and a limited data demand, like DPPS and INITIATOR, seem most suited for regional model application.
Can computer models be used for social learning? A serious game in water management
Wal, Merel M. Van der; Kraker, Joop de; Kroeze, Carolien ; Kirschner, Paul A. ; Valkering, Pieter - \ 2016
Environmental Modelling & Software 75 (2016). - ISSN 1364-8152 - p. 119 - 132.
Serious game - Simulation model - Social learning - Water management
Computer simulation models are increasingly used to support solving complex problems in natural resource management, with social learning as subsidiary goal of the solution process. In this research, a serious game on water management is used where participants receive feedback on consequences of their choices from an Integrated Assessment Meta Model. This study aims to determine if and how social learning takes place and explores the role of the model in social learning. Group discussions were qualitatively analysed to uncover and understand the mechanisms in this process. Results show that social learning took place in 10 of the 12 game sessions. Though model feedback was an important driver for social learning, social learning was driven most by the team's reflection on their perspective. We conclude that using a model can facilitate social learning in a serious-game setting, in particular in combination with reflection on teams' perspectives.