18.4 Wednesday, Jan. 4 The role of the abdominal pump in rhythmic tracheal compression in the ground beetle, Pterostichus tristis DALTON, E.*; SOCHA, J.J.; Virginia Tech; Virginia Tech firstname.lastname@example.org
Abdominal pumping is a widespread behavior in insects, with multiple physiological roles that include respiration and circulation. Although in some insects respiratory patterns have been correlated with abdominal movements, the specific mechanical effects of these movements on the animal's respiratory system are generally unknown. Conversely, some insects (such as beetles, ants, and crickets) create convection in the respiratory system by compressing the tracheal tubes, yet the underlying physiological mechanisms of tracheal collapse are also unknown. This study aimed to investigate the relationship between the abdominal pump and the compression of tracheal tubes in the carabid beetle, Pterostichus tristus. We evaluated the effects of the abdominal pump on CO2 expiration using a high resolution flow-through respirometry system (10 Hz, 1 L/min flow rate) and monitoring the pumping activity of the abdomen by displacement of the dorsal cuticle (IR sensor). The analysis of the relationship between abdominal pumping and external respiratory patterns will provide insight into the functional role of the abdomen in regulating insect gas exchange. To fully test the role of the abdominal pump as a mechanism of internal tracheal compression, future experiments will use x-ray visualization to investigate the timing of tracheal collapse with abdominal movements.