Simulated population dynamics of a stored-products' pest (Ptinus Tectus, coleoptera)

Abstract

Abstract The closed system population dynamics of Ptinus tectus are represented by a difference equation model involving seven forcing functions and 21 system variables. The model is based upon the published work of a number of authors. It is a case study of a complex natural system and is used to predict population curves under varying environmental conditions in teaching autecology. Simulations indicate that in favourable conditions density-dependent mortality and fecundity induce a basic periodicity in thepopulation trajectories. Such periodicity reflects generation time (ranging from 64.5 weeks at 6°C to 12 weeks at 25°C). Environmental factors (temperature, humidity, food bulk dimensions, food quality, food particle size) dictate the position and shape of the trajectory. If environmental oscillations or time delays exist then the periodicity in the population trajectories may become exaggerated, damped, compounded, unstable or chaotic, according to the amount of perturbation.