Sara Aghazadeh – saghaza1@binghamton.edu
Instagram: @saraaghazadeh1016
Department of Mechanical Engineering
Binghamton University (SUNY)
Binghamton, NY, USA

Aishwarya Sriram – asriram@binghamton.edu
Instagram: @sriram.aishwarya
Department of Biological Sciences
Binghamton University (SUNY)
Binghamton, NY, USA

Prof. Carol Miles – cmiles@binghamton.edu
Department of Biological Sciences
Binghamton University (SUNY)
Binghamton, NY, USA

Prof. Ronald Miles – miles@binghamton.edu
Department of Mechanical Engineering
Binghamton University (SUNY)
Binghamton, NY, USA

Popular version of 4pABb3 – The ears of Manduca sexta caterpillars
Presented at the 189th ASA Meeting
Read the abstract at https://eppro02.ativ.me/appinfo.php?page=Session&project=ASAASJ25&id=3982723&server=eppro02.ativ.me

–The research described in this Acoustics Lay Language Paper may not have yet been peer reviewed–

The aim of this research is to explore how insects perceive vibration and sound, ultimately mimic these biological strategies to advance the technology of MEMS microphones. Some insects have tympanal membranes for the detection of sound pressure. These include, for example, katydids and crickets that have tympanal membranes on their forelegs, and the fly, Ormia ochracea that has paired tympanal organs on its prothorax. Most insects and spiders that can hear sound use non-tympanal sensors, such as long hairs on bee and mosquito antennae, and slit sensilla hairs in spiders. We are looking at Manduca sexta, tobacco hornworm caterpillars, a common garden pest devouring tobacco plants. This caterpillar can be found devouring tomato plants in your vegetable garden. While it does respond to sound, it is not clear whether it hears by detecting air-borne sound pressure using a tympanal membrane, hears acoustic particle velocity through the use of sensory hairs, or hears through the detection of sound-induced substrate vibration.

In this study, the caterpillars’ behavioral responses to sound were examined using sounds at two different frequencies: a 150 Hz tone, and a 2000 Hz tone. Previous studies have found strong behavioral responses at 150 Hz in tuning curve experiments. By measuring the sound-induced motion of a thoracic hair using laser vibrometry, we have observed a natural resonance of the hair at 2000 Hz. While we don’t normally expect insect hairs to be effective sound detectors at such high frequencies, this observation motivates further examination to look for behavioral responses.

We monitored caterpillars’ behavioral responses to vibrations of the surface the caterpillars were standing on, and to air-borne sound while we recorded the amplitude of the surface vibration. The results revealed that the caterpillars were 10-100 times more responsive to airborne sound than sound-induced vibration of the surface detected by their feet; this confirms that they perceive airborne sound. Our results show that they can hear airborne sound at a low-frequency of 150 Hz and a high-frequency of 2000 Hz.

We investigated whether certain identifiable thoracic and abdominal hairs enable the caterpillars to hear these specific frequencies through a series of experiments with and without the hairs removed. Please watch the video.

The result of the behavioral response comparisons before and after removal of the hairs on each caterpillar showed a greatly reduced ability of the caterpillars to detect sounds without the hairs. This indicates that M.sexta caterpillars use specific hairs located on their abdomen and thorax for detecting airborne sounds at 150 Hz and 2000 Hz. This provides evidence of non-tympanal sound detection in these caterpillars for these specific frequencies.