Meeting Abstract
The dorsal vessel is a small tube that acts as the primary pumping organ of the insect circulatory system. Posteriorly, the dorsal vessel consists of a muscularized heart which contracts using a peristaltic motion of the heart wall. This motion, which occurs with small amplitudes and without full occlusion of the walls, can produce flows in two directions in some species. However, the mechanics of how the heart pumps are not well understood. To understand how insects create flows within the heart, we are using morphological data from the beetle Zophobas morio to inform new computational models of the dorsal vessel. Geometric characteristics of the dorsal vessel were quantified using dissection and scanning electron microscopy. Initial measurements from 26 specimens indicate that the dorsal vessel (length = 21.5 ± 1.2 mm) occupies 90.1% of the length of the body, with the heart (length = 12.4 ± 0.7 mm) comprising 57.7% of this length. The heart has 6 serially-oriented chambers, with an average chamber length of 1.79 mm (n=5). These findings were used to generate a 3-dimensional model of the insect dorsal vessel using Autodesk Inventor software. Flows within the dorsal vessel were simulated using the immersed boundary method over a range of contraction amplitudes of the modeled heart wall. Peristaltic pumping through flexible tubes at low Reynolds numbers is generally understood to rely on almost full occlusion of the tube walls to generate pulsed flows and net fluid transport. Our model allows us to quantify the net flow of hemolymph and to understand how flows are produced without complete constriction of the vessel. Supported by NSF 1301037 to JJS and NSF 1151478 to LAM.
