FORAGING STRATEGIES IN SOLITARY PARASITOIDS - THE TRADE-OFF BETWEEN FEMALE AND OFFSPRING MORTALITY RISKS

It is often assumed that oviposition rate is the currency that parasit oids should maximize in order to maximize reproductive success. Female parasitoids foraging in a patchy environment face a variety of mortal ity risks that influence the survival of both themselves and their off spring. Maximizing oviposition rate ignores these risks. A model is de veloped to analyse the influence of female and offspring mortality ris ks on optimal patch residence time in time-limited solitary parasitoid s. The optimal compromize between minimizing a female's own mortality risks and the mortality risks of her offspring in characterized. The o ptimal patch residence time is shown to be dependent on the relative m agnitude of these mortality risks, as well as the rate with which repr oductive success accumulates while on a patch. If travel time between patches is not fixed but a random variable, the optimal patch residenc e time decreases. However, variability in travel time increases expect ations of total reproductive success. The model is illustrated with a case study in two aphid parasitoids.