EFFECTS OF TIME LIMITATION AND EGG LIMITATION ON LIFETIME REPRODUCTIVE SUCCESS OF A PARASITOID IN THE FIELD

We used field observations of freely foraging Aphytis aonidiae parasit oids in conjunction with results of laboratory studies of A. aonidiae and other Aphytis species to simulate lifetime patterns of behavior an d reproduction. Field observations provided estimates of encounter rat es with three classes of hosts, the mortality rate from predation on a dult parasitoids, and host-handling times for oviposition and host fee ding by adult wasps. A series of physiological parameters, including t he egg maturation rate and the value of host-feeding meals, were estim ated from previously published studies. Plasticity in parasitoid behav ior was incorporated in two ways. For one set of simulations we used a behavioral rule derived empirically from observations of parasitoids made in the field, and for another we used a dynamic state-variable mo del to generate a set of behavioral rules that maximize lifetime repro ductive success. As was expected, the empirically derived rule led to better matches with field observations than did simulations using the output of the dynamic model. Projections of lifetime reproductive succ ess in the field ranged between three and 37 eggs within the 95% confi dence intervals of the mortality rate and host encounter rate and depe nding on which behavioral rule was used. Lifetime reproductive success from the simulation with central estimates of the mortality and host encounter rates that incorporated the empirical rule was 6.25 eggs. Us ing the empirical versus the theoretical rule in the simulations led t o a 10%-30% decline in projections of lifetime reproductive success, d epending on mortality and host encounter rates. Regardless of the beha vioral rule, the simulations underscored the observation that the host encounter rate was greater than the egg maturation rate. The overall oviposition rate was sufficiently high to lead to daily episodes of te mporary egg limitation during which parasitoids must mature an egg bef ore being able to oviposit.