01757nas a2200097 4500008004100000245004900041210004700090520145100137100002101588856005001609 2003 eng d00aBats and moths: what is there left to learn?0 aBats and moths what is there left to learn3 a

Over 14 families of moths have ears that are adapted to detect the ultrasonic echolocation calls of bats. On hearing a bat, these moths respond with an escape response that reduces their chances of being caught. As an evolutionary response, bats may then have evolved behavioural strategies or changes in call design to overcome the moth's hearing. The nature of this interaction is reviewed. In particular, the role of the echolocation calls of bats in the shaping of the structure, neurophysiology and behavioural responses of moths is discussed. Unresolved issues, such as the structural complexity of the moth's auditory system, the nature of temporal integration and the role of the non‐auditory B cell, are described. Issues in which the interactions between bats and moths may be of more general interest to biologists, such as noise filtering within the central nervous system, protean behaviours and coevolution between predator and prey, are also discussed. The interaction between bats and moths has much to interest general biologists, and may provide a useful model in understanding the neurophysiological basis of behaviour, including protean escape behaviours. The validity of the term coevolution as applied to this system is discussed, as there is no doubt that the auditory system of moths is a response to the echolocation calls of bats, although the evolutionary response of bats to moths is more ambiguous.

1 aWaters, Dean, A. uhttp://www.blackwell-synergy.com/toc/pen/28/402100nas a2200109 4500008004100000245006100041210006100102520173500163100002401898700002001922856004801942 1988 eng d00aTemporal coding in the auditory receptor of the moth ear0 aTemporal coding in the auditory receptor of the moth ear3 a

Temporal coding in the moth ear was inferred from the response of the auditory receptor to acoustic stimuli with different temporal characteristics.

1.Determinations of the threshold with different stimulus pulse durations showed that the moth ear behaves as an energy detector with a maximum time constant (the integration time) of 25 ms. Pulse durations beyond this value did not result in decreased thresholds (Fig. 1).

2.The synchronization to amplitude modulations was determined by stimulating the moth ear with amplitude modulated (AM) tones (carrier frequency: 40 kHz) and AM white noise presented as 450 ms pulses separated by pauses of similar length. The modulation depth was constant (100%) whereas the modulation frequency,fm, was varied. The maximumfm which the auditory receptors could follow was 200 Hz (P<0.05) (Figs. 2, 3, 4).

3.The relatively broad tuning of the only receptor which was functional at the relevant stimulus intensities suggested that AM detection could only be based on temporal cues. This was confirmed by the results showing the same degree of synchronization independent of carrier.

4.A minimum time constant for the receptor was also determined by interrupting a 400 ms noise pulse by a gap (Figs. 5, 6). The threshold for gap detection of the moth ear was ca. 2 ms on a 2.5% significance level (one sided test).

5.The temporal acuity reported here seems to be fine enough to explain the temporal resolution suggested by behavioral results from other insect species. The results are discussed in relation to acoustic communication in insects as well as in relation to temporal resolution in vertebrates.

1 aSurlykke, Annemarie1 aMichelsen, Axel uhttp://link.springer.com/10.1007/BF0060612301326nas a2200157 4500008004100000022001400041245010900055210006900164260001600233300001200249490000800261520073200269100001701001700001401018856013601032 1994 eng d a1471-295400aWingbeat-generated ultrasound in noctuid moths increases the discharge rate of the bat-detecting A1 cell0 aWingbeatgenerated ultrasound in noctuid moths increases the disc cOct-10-1995 a41 - 460 v2583 a

Some noctuid moths produce ultrasound in flight as a consequence of contact between the distal margins of the hindwings. The sound produced from a conspecific 10 mm from the subject increases the discharge rate of the moth’s A1 acoustic cell which functions primarily to detect the echolocation calls of bats. Wingbeat sounds are largely ultrasonic, and may provide background noise through which the moth must recognize bat echolocation calls. The sounds may also limit the lower sensitivity of the auditory system. Wingbeat sounds produced appear to be mismatched to the low-frequency hearing of bats which hunt by passive listening, and are unlikely to be a significant aid to passive aerial foraging by bats.

1 aWaters, D.A.1 aJones, G. uhttp://www.royalsocietypublishing.org/doi/10.1098/rspb.1994.0139https://syndication.highwire.org/content/doi/10.1098/rspb.1994.0139