Predation risk and mating behavior: the responses of moths to bat-like ultrasound

In the presence of predators, animals may reduce or alter their mating activities. There has been little experimental study of whether mating behavior varies with the level of predation risk. Two species of moths, Pseudaletia unipuncta (Noctuidae) and Ostrinia nubilalis (Pyralidae), significantly reduced their mate-seeking behavior under high levels of simulated predation risk. Male moths aborted upwind flight in a pheromone plume, and females stopped releasing pheromone in response to sounds simulating the echolocation calls of bats. For O. nubilalis, but not for P. unipuncta, the response varied significantly with the lever of predation risk. Interspecific differences in behavioral responses likely reflect differences in physiological auditory sensitivity and/or behavioral thresholds. Female behavioral responses to sounds simulating the calls of bats that glean their prey from surfaces were significantly weaker than their responses to sounds resembling the calls of aerially hawking bats; these results support the neurophysiological data that the calls of gleaning bats are relatively inaudible to moths. This study indicates that some animals can modify their reproductive activities in response to auditory cues from predators.