Listening in pheromone plumes: Disruption of olfactory-guided mate attraction in a moth by a bat-like ultrasound

Abstract:
Nocturnal moths often use sex pheromones to find mates and ultrasonic hearing to evade echolocating

bat predators. Male moths, when confronted with both pheromones and sound, thus have to trade off

reproduction and predator avoidance depending on the relative strengths of the perceived conflicting

stimuli. The ultrasonic hearing of Plodia interpunctella was investigated. A threshold curve for evasive

reaction to ultrasound of tethered moths was established, and the frequency of best hearing was found

to be between 40 and 70 kHz. Flight tunnel experiments were performed where males orienting in a sex

pheromone plume were stimulated with 50 kHz pulses of different intensities. Pheromone-stimulated

males showed increased defensive response with increased intensity of the sound stimulus, and the

acoustic cue had long-lasting effects on their pheromone-mediated flight, revealing a cost associated

with vital evasive behaviours.