Weather-mediated regulation of olive scale by two parasitoids

1. The effects of temperature and interspecific competition among two paras itoids (Aphytis maculicornis (=paramaculicornis) (Masi)-Coccophagoides util is Doutt) of the olive scale (Parlatoria oleae (Colvee)) were examined, and the reason for the successful biological control of olive scale explained. 2. An age-structure distributed maturation time model of this system was de veloped that simplifies many of the details of prior physiologically based models. 3. Temperature-dependent physiological indices were used to scale fecundity and survivorship rates from their maximum values. 4. The distributed maturation time population dynamics model captured the v ariance in temperature-related development times required to simulate the d ynamics of the system. 5. A type III ratio-dependent functional response was used to estimate para sitism rate on olive scale and also served to stabilize our single patch mo del. 6. The model confirms the Huffaker & Kennett (1966) conclusions concerning the role of weather and the relative contribution of the two parasitoids in the regulation of olive scale in California olive.