Ultrasonic hearing in moths

Abstract

Abstract. Many moths possess ultrasound-sensitive ears, directly resulted from bat predation. Moth ears display an abundant diversity due to their body location, accessory structures, and number of auditory sensory cells. Anatomically, the moth ears are the simplest hearing organs in insects and most are tympanal organ with a tympanum. Eared moths have an optimal frequency range between 20 kHz and 50 kHz, which coincides with the peak frequency used by most insectivorous bats. The primary function of the moth ear is to detect and avoid the hunting of bats. Eared moths show a series of defensive behaviors, when they are exposed to the cries emitted by insectivorous bats. The presence of these tympanal organs also set the stage for the later evolution of ultrasonic courtship signals in the eared moth families. Over the years, entomologists worldwide have performed large numbers of studies on hearing of moths and their interactions with bats. This paper presents an overview of moth hearing, focusing on morphology, neurophysiology, and behavioral ecology.Résumé. L'audition ultrasonique chez les papillons nocturnes. Beaucoup de papillons de nuit ont des organes d'audition sensibles aux ultrasons, ce qui résulte d'une adaptation à la prédation par les chauve-souris. Ces organes d'audition présentent une abondante diversité en ce qui concerne leur position sur le corps, leur structure, et par le nombre de cellules sensorielles. Anatomiquement, ces organes d'audition ont une fréquence optimale de réception comprise entre 20 et 50 kHz, ce qui coincide avec le pic des fréquences utilisées par la plupart des chauves-souris insectivores. La fonction primaire de ces organes est de détecter la chasse par les chauves-souris et de permettre d'y échapper. Les espèces pourvues de ces organes présentent toute une série de comportements défensifs dès qu'elles sont exposées aux cris émis par les chauves-souris. La présence d'organes tympaniques parvient à un stade tel qu'elle permet l'évolution de signaux ultrasoniques de parade nuptiale chez plusieurs familles. Depuis longtemps, les entomologistes du monde entier ont fait de nombreuses études sur l'audition des papillons nocturnes et ses interactions avec les chauves-souris. Le présent article présente une revue de l'audition de ces lépidoptères, avec une attention particulière sur la morphologie, la neurophysiologie et l'éco-éthologie.

Light-emitting diode street lights reduce last-ditch evasive manoeuvres by moths to bat echolocation calls

“…However, all were relatively large and probably belonged to the families Geometridae, Noctuidae or Notodontidae. Moths in these families possess ultrasonic hearing [ 24 ] and comprised more than 90% of moths attracted to artificial lights in southwest England [ 6 ]. The video camera, infrared light, D1000X bat detector and ultrasonic speaker were mounted on custom-made housing (electronic supplementary material, figure S2) at approximately 1.4 m and aimed towards subject moths.…”

Species‐specific strategies increase unpredictability of escape flight in eared moths

“…As N. fimbriata and H. armigera did not change their flight strength in response to our stimulus, consisting of 35 kHz pure tones at 80 dB SPL RMS, it is possible that our stimulus was inaudible for those species, or audible yet too faint to trigger evasive flight or to be perceived as sufficiently high predation risk. Although neuronal audiograms of multiple species suggest that our stimulus is above the threshold of the A2 cell of moths (Gordon & ter Hofstede, 2018;Ter Hofstede et al, 2013;Surlykke, 2003;Zha et al, 2009), little is known about how neuronal activity translates into evasive flight. Behavioural thresholds are generally higher than neuronal thresholds, although the exact differences and potential variation between species are mostly unknown (for discussion, see Lewanzik & Goerlitz, 2017) etation could be a potential anti-predator strategy, as close-by background structures impair bats' capture success due to sensory and motor constraints (Siemers & Schnitzler, 2004).…”

“…Last‐ditch flight behaviour in many moths is supposed to be elicited by activation of the auditory receptor neuron A2 (Gordon & ter Hofstede, ; Madsen & Miller, ; Roeder, ). A2 sensitivity depends on frequency, having highest sensitivity between 15 and 60 kHz (Gordon & ter Hofstede, ; Ter Hofstede, Goerlitz, Ratcliffe, Holderied, & Surlykke, ; Madsen & Miller, ; Surlykke, ; Waters & Jones, ; Zha, Chen, & Lei, ). We therefore designed a stimulus to elicit last‐ditch flight behaviour and mimicking an attacking bat (Schnitzler & Kalko, ; Schnitzler, Moss, & Denzinger, ; Skiba, ), consisting of 120 pure tones at 35 kHz, each having 4‐ms duration plus 0.5‐ms raised‐cosine ramps and 25‐ms pulse interval (PI), resulting in a total length of 2.98 s. Sound pressure level at the moth was 80 dB SPL RMS re.…”

“…We therefore designed a stimulus to elicit last‐ditch flight behaviour and mimicking an attacking bat (Schnitzler & Kalko, ; Schnitzler, Moss, & Denzinger, ; Skiba, ), consisting of 120 pure tones at 35 kHz, each having 4‐ms duration plus 0.5‐ms raised‐cosine ramps and 25‐ms pulse interval (PI), resulting in a total length of 2.98 s. Sound pressure level at the moth was 80 dB SPL RMS re. 20 µPa, that is, about 8 to 17 dB above A2 threshold depending on moth species (Gordon & ter Hofstede, ; Ter Hofstede et al, ; Surlykke, ; Zha et al, ). We recorded moth flight strength for 6 s, starting 2 s before stimulus onset until about 1 s after the stimulus ended.…”

“…Sound pressure level at the moth was 80 dB SPL RMS re. 20 µPa, that is, about 8 to 17 dB above A2 threshold depending on moth species (Gordon & ter Hofstede, 2018;Ter Hofstede et al, 2013;Surlykke, 2003;Zha et al, 2009). We recorded moth flight strength for 6 s, starting 2 s before stimulus onset until about 1 s after the stimulus ended.…”