The cotton insect model, TEXCIM, simulates the population dynamics and the damage to cotton caused by three insect species: boll weevil, Anthonomous grandis grandis Boheman, cotton fleahopper, Pseudatomoscelis seriatus (Reuter), tobacco budworm, Heliothis virescens (F.) and cotton bollworm, H. zea (Boddie). A submodel simulates the dynamics of cotton fruit in response to the insects and allows estimation of the economic damage that results. The cotton model, GOSSYM, is a physiological model that simulates soil moisture, root and plant growth and fruiting behavior. The Heliothis damage model, HELDMG, is designed to work with GOSSYM and simulates the damage caused by a given number of Heliothis larvae. It also predicts the position the damage will occur on the plant.

Recently, the computer code for the three models has been combined so that the numbers of Heliothis larvae predicted by TEXCIM are passed to the HELDMG routine, that in turn reduces the number of fruit in the GOSSYM model. The fruit prediction from GOSSYM is used in turn by TEXCIM to predict the number of Heliothis eggs that will be layed. Another damage routine has been programmed, based on elements front TEXCIM and HELDMG, to simulate the damage of cotton fleahopper on the cotton plant. It remains to design and install an equivalent damage model for boll weevil. The resulting model will provide an improved tool for researchers to study the response of the cotton plant to damage by single and multiple species of insects.