Acoustic orientation via sequential comparison in an ultrasonic moth

Abstract

Orientation of female lesser wax moths (Achroia grisella) to male calling song was tested on a locomotion-compensator device that withheld all inter-aural acoustic differences from the insect. Under these circumstances, females remained longer in the vicinity of the sound source if they experienced a variable sound level that increased when approaching the source rather than a level that remained constant at all times. Analyses of orientation paths revealed that greater retention near the source was achieved by enhanced turning when the perceived sound level remained unchanged or decreased but retaining the previous heading when the level increased. These findings suggest that acoustic orientation can be supplemented by mechanisms based on sequential, as opposed to instantaneous, comparison of auditory input. Such mechanisms may be valuable when binaural hearing is impaired or asymmetric or in environments where acoustic differences at the two ears are unreliable indications of direction to the sound source.

Directional hearing: from biophysical binaural cues to directional hearing outdoors

“…The core of this model for spatial orientation is the suggestion, that it requires a sequential analysis of binaural cues, thus involving memory. This is supported by a study on the lesser wax moth Achroia grisella (Greenfield et al 2002 ), where all interaural acoustic differences for females orienting toward the male advertisement call have been experimentally removed. Their findings also suggest that receivers may adjust their phonotactic movement in accordance with a sequential comparison of auditory input.…”

Evolution of directional hearing in moths via conversion of bat detection devices to asymmetric pressure gradient receivers

“…The moths do waver from a precise heading, of course, which may have several consequences. Small departures from +30°or −30°might be corrected by random turning or a sequential comparison algorithm, a mechanism that A. grisella are known to possess (24). Larger departures can result in locking onto the stimulus with the other ear ( Fig.…”

Transmission of the frequency components of the vibrational signal of the glassy-winged sharpshooter, Homalodisca vitripennis, within and between grapevines

“…Furthermore, studies of the nocturnal desert scorpion, Paruroctonus mesaensis, showed that it responded to time differences of 0.2 ms between vibrations delivered to different legs (Brownell and Farley 1979). Finally, insects, such as the lesser wax moth, Achoria grisella , use sequential signal analysis to orient and find their mates (Greenfield et al 2002). Therefore, implications of our findings in light of these studies are that, in theory, arthropods may be able to use differences in the time of arrival of the harmonics to estimate the distance to and the direction of a duetting partner.…”