Influence of Host Deprivation and Egg Expenditure on the Patch and Host-Finding Behavior of the Parasitoid Wasp <Emphasis Type="Italic">Mastrus ridibundus</Emphasis>

The influence of host deprivation and egg expenditure on the host location behavior ofMastrus ridibundus was evaluated under controlled conditions in a walk-in field cage in a greenhouse. The activity of females peaked at a temperature of 25–27°C generating two peaks of activity through the day. Increased host deprivation did not influence patch and host-finding success: females responded to host stimuli even after 9 days of host deprivation. In contrast, the longer M. ridibundus was exposed to excess hosts, the greater was the reduction in patch and host-finding success. Egg depletion expressed as the percentage of realized lifetime fecundity expended, rather than egg load, offered a good match for this decline. These results are discussed in the context of biological control introductions and the choice of pre-release treatment.