Phonotactic behaviour and vertical sound source localisation of the parasitoid fly Emblemasoma auditrix (Diptera: Sarcophagidae)

Abstract

1. Acoustically guided movement in a three-dimensional space is a complex behavioural task performed notably by birds, bats, and some insect species. The precision of acoustic orientation depends on the directionality of the hearing system as well as on auditory behaviour.2. The fly Emblemasoma auditrix Diptera (Sarcophagidae) is a parasitoid of the cicada Okanagana rimosa Auchenorrhyncha (Cicadidae) and locates its host in the complex habitat of a forest. The phonotactic behaviour of the fly was analysed experimentally with emphasis on the vertical domain in the field. Different experimental setups allowed discriminating subsequent steps in the phonotactic behaviour of E. auditrix.3. During the phonotactic flight, flies first landed on landmarks, which were used to re-adjust to the elevation of the sound source. Acoustic targets were located from these resting positions. The sound source elevation was detected at the start of the flight as the longitudinal body axis was adjusted to the inclination of the target sound source.4. Flies usually did not land directly upon the sound source, but landed nearby, and most often above the target. Within the target area, types of movement for the final approach differed in respect to target position; flies walked predominantly if the final target was located above or below, but for horizontally located targets much of the distance was covered by flight.5. In conclusion, E. auditrix can locate the acoustic target in complex habitats and uses a flexible multi-step approach for short-range phonotaxis.

The Auditory System of the Dipteran ParasitoidEmblemasoma auditrix(Sarcophagidae)

“…The parasitoid fly E. auditrix uses its auditory system to locate the male cicada Okanagana rimosa by its CS. Although aspects of the behavior and the evolutionary novelty of the hearing sense have already been described ( Köhler and Lakes-Harlan 2001 , Lakes-Harlan and Köhler 2003 , Schniederkötter and Lakes-Harlan 2004 , de Vries and Lakes-Harlan 2005 , Tron et al 2015 ); here, the anatomy of the ear and the auditory physiology are discussed in order to understand the properties of the hearing sense of E. auditrix .…”

Adaptive Strategies in Life-History of Bushcrickets (Orthoptera) and Cicadas (Homoptera) to Parasitoids Pressure on Their Acoustic Communication Systems—A Case for Sociality?

“…Even simple female phonotaxis is rarely studied in cicadas (but see Doolan and Young, 1989;Daws et al, 1997), and female sexual selection less so. Nevertheless, calling is a prerequisite for O. rimosa males to attract females (Stölting et al, 2004) and this signal is similarly exploited by the parasitoid E. auditrix (Lakes-Harlan et al, 2000;Tron et al, 2015). Interestingly, the cicada choruses might distract the acoustically hunting parasitoid, as it's phonotaxis is tuned to the temporal structure of an isolated calling song (Lakes-Harlan et al, 2000).…”