Silent singers are not safe: selective response of a parasitoid to substrate-borne vibratory signals of stink bugs

The egg parasitoid Telenomus podisi Ashmead (Hymenoptera: Scelionidae) can eavesdrop on vibratory signals of adult stink bugs. Here, we tested the hypothesis that the parasitoid can selectively respond to the sex- and species-specific songs of different stink bugs. Two-choice plant bioassays were performed using dried bean plants with two expanded opposite leaves that were vibrated with played-back signals or with naturally produced signals from live insects placed on plants. Each leaf was vibrated with signals of the host Euschistus heros Fabricius (Hemiptera: Pentatomidae), the alternative host Piezodorus guildinii (Westwood) or the nonhost Chinavia impicticornis (Stål) (played back). Parasitoid females showed a selective response to the female songs of E. heros when these songs were tested against male songs or male–female duets. Telenomus podisi females also preferred E. heros female songs to female songs of the other pentatomid bugs tested. Our results show that T. podisi females respond selectively to female songs of their preferred host (E. heros); this behaviour may have relevant adaptive significance for the parasitoid, allowing it to forage in microhabitats with increased probability of finding host eggs. We discuss the ecological significance of the use of vibratory signals and interactions with other (chemical) cues during the host-searching behaviour of T. podisi.