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Major steps to develop a model

Principally four steps are required:

  1. Collect life-table data in temperature experiments or, if available, from the literature.
  2. Define the functions describing the temperature-driven processes in insect development using the model builder and compile the over-all model that is realized by ILCYM interactively.
  3. Validate the model in ILCYM, using data from the literature or from experiments conducted under fluctuating temperatures and conduct sensitivity analysis.
  4. Apply the model for “pest risk assessments and mapping” in the second module of ILCYM.

The following points should be considered when developing phenology models:

  1. What is your aim in developing a phenology model and is the ILCYM approach the right one for your
    target species?
  2. Collect literature on the species for which you want to develop a phenology model. What is known about the biology of this species? Are literature data available that could be used for modeling or model validation?
  3. Define hypothesis! Ultimately you are working on a piece of science, and science requires hypothesis.
  4. Design and plan your experiment properly! You will need adequate insect rearing facilities, at least 1-2 incubators for constant temperature experiments (depending on the species in a range of 10ºC to 30ºC in 5ºC steps), thermometers or loggers to monitor temperature, etc.
  5. You may use dummy data provided in ILCYM to get familiar with the analysis and learn about the approach. You might also create your own dummy data with different numbers of temperatures and different numbers of insects in the experiment for learning about the statistical precision of your planned experiment. Decide about the type of data you want to collect.
  6. Collect the data in temperature experiments and input data into ILCYM.
  7. Use ILCYM’s “model builder” defining all the sub-models for the overall phenology model. At this stage you might start writing a report on the results obtained. You can print the graphs and use them in your report.
  8. Once all sub-functions are selected, ILCYM compiles the overall model automatically according to the initial statements you have input when starting a new project in ILCYM. At this stage you should be quite familiar with the structure of the overall model and the modeling approach of ILCYM.
  9. Conduct sensitivity analysis and validate the model by comparing simulation results with the data from fluctuating temperature experiments or data published in the literature. ILCYM provides tools for that. At this stage you might finalize the report about your model developed.
  10. Employ the model for your purposes. You may want to apply the new model for “pest risk mapping”, which is the second part of ILCYM. Here you can produce maps indicating population growth potentials for a region of interest.

The data collection may take a long time because of the slow development of insects at cold temperatures. Certain insects may then need one year to complete the whole life-cycle. In such conditions the cohort approach for collecting the data might be better than establishing a life-table where a whole life-cycle of one generation will be monitored. As a rule, developing a pest phenology model should not take longer than one year.

Software Associated

R 3.4.1






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