FORAGING AND OVIPOSITION DECISIONS IN THE PARASITOID APHYTIS-LINGNANENSIS - DISTINGUISHING THE INFLUENCES OF EGG LOAD AND EXPERIENCE

(1) We used an experimental protocol that allowed us to distinguish the relative influences of egg load and experience with host contact on foraging behaviour and clutch size decisions in the gregarious parasitoid Aphytis lingnanensis Compere. Egg load was manipulated without concurrent changes in experience by exploiting size-related variation in fecundity and by holding parasitoids at different temperatures to vary the rate of egg production. (2) Egg load influenced the intensity of searching behaviour. Parasitoids with smaller egg loads required more time within a foraging arena to discover hosts. (3) Parasitoids with smaller egg loads and parasitoids with a prior experience with host contact deposited smaller clutches. (4) Total host handling time was inversely related to parasitoid egg load. Increased egg load had a similar accelerating influence on each of the component activities that comprise host handling, including preparation for oviposition, oviposition, and post-oviposition grooming and resting. (5) The probability of successful parasitoid egg to adult development was independent of clutch size. Progeny size, however, decreased with increasing number of competing sibs. (6) A. lingnanensis clutch size decisions do not conform to the static expectations of a forager maximizing the fitness gained per egg, per host, or per unit time. Rather, clutch size decisions appeared to be fundamentally dynamic, responding to changes in parasitoid physiology (egg load) and the parasitoid's perception of host availability (experience).