Infection behavior of a parasitoid fly, Emblemasoma auditrix, and its host cicada Okanagana rimosa

Abstract

Males of the cicada Okanagana rimosa (Homoptera: Cicadidae) that produce calling songs are parasitised by the parasitoid fly Emblemasoma auditrix (Diptera: Sarcophagidae). An ethogram of the infection behavior was extracted from videotaped experiments with tethered hosts. The infection behavior can be divided into three phases, each involving different sensory cues: long-range host detection via acoustic signals, visual short-range orientation, and a contact phase with tactile/chemical cues. After phonotaxis by flight, the fly lands on or near the host cicada. It walks around the host to identify the caudal end and squeezes underneath the wings (with a 64-67% preference of the left side). Finally, E. auditrix cuts into the timbal and deposits a larva into the sound producing organ of O. rimosa. This highly specific behavior restricts the host range to cicadas, only two species of which occur simultaneously with the parasitoid. During the infection behavior, the fly does not discriminate between male and female hosts. However, females were not successfully infected during the experiments. The host O. rimosa shows only weak defense behavior (mainly flapping their wings) and seems to rely on parasitoid avoidance. Production of the protest song does not prevent infection.