Computer code for a model describing the emergence of a long transient regular spatial pattern from interaction of competing aquatic macrophytes and a biocontrol agent

A spatially explicit simulation model was developed for competition between floating (FAV) and submersed (SAV) aquatic vegetation in which an insect biocontrol agent (weevil) consumes FAV biomass. In all simulations, a dynamic regular striped pattern of rock-scissors-paper (weevil-FAV-SAV) eventually forms and persists for thousands of days despite stochastic disturbances in the form of added adult weevils. At some point in the simulation, depending on the random number initiator, an apparently insignificant spatial deviation in small set of pixels triggers an instability that grows rapidly until the striped pattern has been replaced by a chaotic-appearing pattern. Investigation shows that the time lags involved in the weevil life cycle and assumptions on spatial movement lead to the instability and end of long transient.  This research reveals the detailed mechanisms by which a long transient striped pattern transitions to an irregular pattern, offering insights into how spatial patter..., No raw data were generated by this research.  All of the data used in the model simulations as parameter values are from published papers. McCann (2016) parameterized the model of competition between SAV and FAV based on the submersed plant Nuttall’s waterweed (Elodea nuttallii) and the floating duckweed Lemna gibba. We used the parameters of those species, and used the parameters of N. eichhorniae, as the biocontrol agent, from van Schalkwyk (2016) although that is only hypothetical for the present situation, as we do not know parameters for a relevant herbivore of L. gibba.  All these parameters are shown in Tables that have been uploaded. The parameter values are also in Xu and DeAngelis (2024). Hyperlinks for these papers have been uploaded., , # Computer Code for Xu and DeAngelis 30October2024

[https://doi.org/10.5061/dryad.ht76hdrrp](https://doi.org/10.5061/dryad.ht76hdrrp)

## Description of the data and file structure

There are two tables of parameter values that were used as input for the simulation model code “CAmodeltest_Switch_Biocontrol_15September2024”.

### Files and variables

No data files or variables were uploaded.

## Code/software

The Matlab code consists of the script “CAmodeltest_Switch_Biocontrol_15September2024”.

The script CAmodeltest_diffuseN_07April2023_Biocontrol simulates the interaction of two competing aquatic macrophytes, on a 50 x 50 spatial lattice of patches. The variables are

‘WH(i,j)’ = floating aquatic vegetation (FAV) biomass, water hyacinth

‘S(i,j)’ =  submersed aquatic vegetation (FAV) biomass

 An insect biocontrol agent feeds on the FAV. The variables for the adult are

‘Adult(i,j)’  =  adult biocontrol insect numbers.

A fourth variable is the limiting nutrient concentration

‘nwh...