Meeting Abstract
The alimentary canal of insects is a large, continuous tube running from the mouth to the anus, loosely connected to other internal organs via tracheal tubes. Dynamical movements of this organ can affect the surrounding tissues and fluids, but mechanics of such movements have not been well studied. Peristalsis has been suggested to influence hemolymph flow and respiratory ventilation, but there is no direct observation of such linkages. In this study, we used synchrotron X-ray imaging, pressure recordings, and videography to simultaneously observe gut motion, hemolymph pressure, and abdominal movements in the tenebrionid beetle Zophobas morio. In addition, we determined the three-dimensional morphology of the gut using micro tomography. X-ray imaging of the live beetles revealed that the gut not only exhibits peristaltic motion, but also shows frequent anterior-posterior pulsatory movements. Furthermore, the pulsatory movement of the gut, unlike peristalsis, is correlated with hemolymph pressure pulses (2.79 ± 0.8 kPa), abdominal pumping, and tracheal tube collapse, which occur on average with a frequency of 12 per minute. Our preliminary results show that, during each pulsatory motion of the gut, the volume of the esophagus increases up to 35% in 0.5 seconds. Therefore, this fast expansion of the gut in the thorax may influence multiple physiological systems by altering hemolymph pressure, compressing tracheae, and possibly pumping hemolymph into the appendages. Supported by NSF 1558052.
