A MODEL TO DESCRIBE THE REPRODUCTIVE RATE IN THE APHID SITOBION-AVENAE (HEMIPTERA, APHIDIDAE) - A CASE-STUDY

The development of a detailed population dynamics model to simulate ch anges in grain aphid (Sitobion avenae F.) populations on wheat in fiel d conditions requires the identification of every component of the sys tem. The present study proposes a deterministic model for the fecundit y function. An optimality theory is applied here to model aphid reprod uction in order to obtain a usable mathematical description of larvae laying rate. This rate is assumed to be mainly dependent on temperatur e since this effect is commonly observed in poikilothermic organisms. It is taken into account by using a thermodependent physiological time scale for measuring adult age. The resulting function is fitted with two data sets. Despite some bias, which is discussed, the model matche s relatively well with the observations. The model framework may be ea sily extended to other species.