Host Location of a Pupal Parasitoid in a Tritrophic System Compared to a Model Offering Mechanosensory Cues Only

Several species of hymenopteran parasitoids are able to locate concealed pupal hosts by vibrational sounding. However, the specific role of this technique of mechanosensory host location has not yet been investigated in a natural, tritrophic system with multiple cues. Here we compared the host location of the pupal parasitoid Xanthopimpla stemmator in a tritrophic system with corn borer pupae in maize stem to the behavior on a paper model offering mechanosensory cues only. In general, the behavioral pattern and the behavioral states exhibited by host-searching female parasitoid were identical in the model and in the tritrophic system, while quantitative aspects differed. Our results demonstrate that vibrational sounding maintains its significance for host location in an environment with multiple cues, and that additional cues may increase responsiveness of females.