Meeting Abstract

100.2  Monday, Jan. 6 14:00  What happens when pupae pump? Internal effects of abdominal movements in the beetle Zophobas morio KENNY, M*; PENDAR, H; ADJERID, K; SOCHA, JJ; Virginia Tech; Virginia Tech; Virginia Tech; Virginia Tech mck66@vt.edu

During metamorphosis, pupal insects exhibit an immobile stage, during which multiple physiological systems undergo extensive remodeling. However, the abdomen retains its ability to move and exhibits periodic contractions via the intersegmental muscles. These movements are postulated to regulate circulation and potentially to control respiratory ventilation. Despite extensive research on pupae, little is known about the volumetric deformation of the tracheal system. Generally, the lower metabolic demands of immobility are thought to limit the need for active ventilation. Here, we test the relationship between abdominal movement, internal pressure, and tracheal deformation to determine the role of active ventilation in the pupal life stage. Synchrotron x-ray imaging was used to visualize the internal body of darkling beetle pupae (Zophobas morio) at the Advanced Photon Source at Argonne National Laboratory. Simultaneously, hemolymph pressure and movement of the abdomen were recorded using a fiber optic pressure sensor and infrared sensor, respectively. During bouts of abdominal pumping, we observed pressure pulses on the order of 1-2 kPa, accompanied by correlated movements of the abdomen and the gut. Additionally, select tracheal tubes were compressed during some, but not all, pulsatory events. During rest between pulsations, all visible movements (both internal and external) were absent. In pupae approaching ecdysis, active abdominal pumping was more frequent and in some cases continuous, with a lack of resting stages. Tracheal compression was also observed to be more regular in pupae at this stage, suggesting that active ventilation becomes more prominent as the pupae approach the adult stage. Supported by NSF 0938047.