Meeting Abstract
Hemolymph is pumped throughout an insect’s body and appendages by peristaltic contractions of the dorsal aortic vessel, and in larger insects, with the assistance of accessory pulsatile organs. Continuous flow is necessary for the transport of nutrients, removal of waste, and support of an active immune system. Unconstrained by a vascularized network until it enters the wing, hemolymph actively flows into the wing and its system of veins with the assistance of a pulsing wing “heart.” The veins transport hemolymph, contain trachea and nerves, and provide structural support for the wing. While many structural aspects of insect wings have been characterized, hemolymph dynamics and the physics mediating this flow within the wing and its pumping organs remain largely unknown. We observed these hemodynamics within live adult American Bird Grasshoppers (or commonly American Locust), Schistocerca americana (Family: Acrididae). This genus, known for occasional swarming, is a competent and energetic flier with a wing span of ~5 cm. We tracked fluorescent particles within the wing, pulsatile organs at the wing hinge, and dorsal abdominal segments to determine flow direction, Reynolds number and pressure distributions within the wing. Contrary to suggestions in previous literature, we present evidence of uniform, pulsatile, and bi-directional flow in the longitudinal veins and cross veins, across the span and chord of both fore and hind wings. These results highlight the importance of the pulsatile organs and of fluid flow through insect wing veins, and suggest that fluid transport in the wings may play an important role during flight.
