| As shown in a recent study, cocoon-spinning larvae of the codling moth, Cydia pomonella L. (Lepidoptera: Olethreutidae) employ a pheromone that attracts or arrests pupation site seeking conspecific larvae. Such intraspecific communication signals are important cues for illicit receivers such as parasitoids to exploit. I tested the hypothesis that the specialist prepupal C. pomonella parasitoid Mastrus ridibundus Gravenhorst (Hymenoptera: Ichneumonidae) exploit the larval aggregation pheromone to locate host prepupae. In laboratory olfactometer experiments, female M. ridibundus were attracted to 3-day-old cocoons containing C. pomonella larvae or prepupae. Older cocoons containing C. pomonella pupae, or larvae and prepupae excised from cocoons, were not attractive. Mastrus ridibundus obviously eavesdrop on the pheromonal communication signals of C. pomonella larvae that reliably indicate host presence. Whether the larval aggregation pheromone is as complex as the semiochemical blend attracting M. ridibundus is currently under investigation. (Abstract shortened by UMI.). |
