Submitted to: Annals of the Entomological Society of America
Publication Type: Abstract Only
Publication Acceptance Date: 3/11/2002
Publication Date: N/A
Technical Abstract: In the Nezara viridula - Trissolcus basalis system (Patatomidae - Scelionidae), previous laboratory investigations demonstrated that,although searching parasitoids do not detect an odor from the host eggs, they do respond to traces left on the substrate by adult bugs. Thus, the host traces seem to play an important role as a general kairomone associated with the possible presence of host eggs. In fact, even naive females of T. basalis spent more time in the area contaminated with traces left by the mated females in a pre-ovipositional condition than in an area with traces from males. We hypothesize that the kairomone is correlated with the possible host egg finding, and that it is adaptive for a parasitoid to selectively respond to the preovipositional female. According to this hypothesis, the experienced females that were in the presence of the contact kairomone without finding the host eggs, should behave differently from naive wasps. In the same way, the experienced females that oviposited in the presence of the contact kairomone should show a different behavior. Our investigations agreed with these predictions. In fact, the wasps which experienced the kairomone without finding host eggs showed statistical differences in their behavioral parameters with respect to the naive wasps. Similarly, significant differences were recorded between females that found and oviposited in host eggs in the presence of the contact kairomone compared to female wasps that experienced only the kairomone. Our findings suggest the existence of a hierarchy of stimuli guiding the wasps in the location process and extending the search of the target on the substrate.