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Bee thermoregulation

Please note

The simulation needs a Java-Plugin (1.3.x) installed for your internet browser. If you do not already have one installed, the browser will prompt you to download the Plugin from Sun, who is the inventor of Java. Please download the JRE (=Java runtime environment) into a directory on your computer (e.g. c:\temp), execute the downloaded file for installation on your system (double-click on the file). Afterwards you will be able to reload the simulation page. Maybe you will have to restart your browser to succeed.

Run the simulation

Please click here.

Description of the model

This program simulates the cluster formation of bees in times of low ambient temperatures. It represents a comb with a set of bees moving on. Only one bee can be located at the same time on a place (= one patch). While bees move randomly in their preferred temperature range, they move directed when they are outside this range to find places with better environment. Below a certain temperature they fall into a chill coma (cannot move anymore). Moving bees produce heat according to the temperature in the environment. Heat diffuses between patches, whereby chilled bees hinder this flow a bit and therefore have an insulating effect. The outside-world is represented by a red border, that allows to change the ambient temperature and bring this changes into the model. The temperature on each place (patch) is shown in green. The brighter the green, the warmer is the patch.

Implementation

This simulation is based on the article:

  • D.J.T. Sumpter & D.S. Broomhead "Dynamics of Thermoregulating honey bee clusters" J. theor. Biol 204 (2000): 1-14

Rules (assumptions)

  1. Bees in their preferred temperature range (yellow): Random walk, but avoid sharing a patch with another bee and avoiding the red border. Produce heat based on the hq20-value (= the amount of heat produced by a bee in an environment of 20C). The warmer the surrounding, the more heat is produced. Active-heating (as seen by bees) is omitted, so the simulation is only valid for temperatures above a certain level (e.g. above 9C). Diffusion coefficient of patches containing such bees: 1
  2. Bees outside their preferred range (orange): Move towards their preferred range. This bees also avoid collisions and border and also produce heat. Diffusion coefficient of patches containing such bees: 1
  3. Bees below the chill-threshold (blue): This bees are in coma and cannot move anymore. Diffusion coefficient of patches containing such bees: 0.45 (-> insulating effect)
  4. Diffusion coefficient of empty patches: 1

Differences to the original presented model of Sumpter & Broomhead

I had to raise the heat production by the factor 36 to achieve comparable results as shown in the paper. This might be due to the effect that in the simulation described in the article, a finer lattice was used to treat temperature production and diffusion. I think they also calculated this processes several times more frequently than the calculation of the bees movements. Unfortunately, StarLogo does not support differently scaled lattices and is not fast enough for multiple diffusions.

Experiments

Start with ambient temperature at 20C and 200 bees. Then lower the ambient temperature to 13C. watch the size and the form of the cluster that forms.

Start with ambient temperature at 20C and 100 bees. Then lower the ambient temperature to 13C. watch the size and the form of the cluster that forms.

Start with ambient temperature at 20C and 100 bees. Then lower the ambient temperature to 11C. watch the size and the form of the cluster that forms.

Start with ambient temperature at 20C and 200 bees. Then lower the ambient temperature to 9C. watch the size and the form of the cluster that forms.

Screenshot

Implementation

The presented StarLogo simulation was written by:
Thomas Schmickl (2002), Department for Zoology, Karl-Franzens-University Graz, Austria, Europe,
schmickl@nextra.at, thomas.schmickl@uni-graz.at

The model eas inspired by Sumper & Broomhead (see above), who themselves were inspired by the heatbugs model included in the documentation of the SWARM multi agent simulation toolkit (see www.swarm.org ).

Further readings

  • D.J.T. Sumpter & D.S. Broomhead "Dynamics of Thermoregulating honey bee clusters" J. theor. Biol 204 (2000): 1-14
  • Myerscough M.R. (1993) A simple model for temperature regulation in honeybee swarms. J. Theor. Biol. 162:381-393
  • Camazine S., Deneubourg J.-L., Franks N.R., Sneyd J., Theraulaz G. and Bonabeau E. (2001) Self-Organization in biological systems. Princeton University Press.

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