Meeting Abstract
Insects acquire pathogens via ingestion and through breaches in the cuticle. Upon entry into the hemocoel, pathogens are circulated throughout the body by the insect open circulatory system. Anatomically, this circulatory system consists of a hemocoel, a series of muscular pumps, and a fluid medium called the hemolymph. The primary circulatory organ is the dorsal vessel, which is a muscular tube-like structure that extends along the dorsal midline of the insect and is divided into a thoracic aorta and an abdominal heart. Hemolymph enters the dorsal vessel through ostia that are located at the thoraco-abdominal junction and in each abdominal segment. Once inside the dorsal vessel, hemolymph is propelled across the body and is sequentially released back into the hemocoel at the terminal ends of the insect. Hemolymph then flows back toward the heart and reenters the vessel through the ostia. During an infection, pathogens are swept throughout the body by the swift flow of hemolymph. As they do so, they encounter insect immune factors that range from soluble cytotoxic peptides to immune cells called hemocytes. Recent work has uncovered that the insect circulatory and immune systems have co-adapted to fight infection. This presentation will summarize the structural mechanics of hemolymph circulation in insects (with a special emphasis on mosquitoes), and will detail how infection induces the aggregation of hemocytes on the surface of the insect heart, where they phagocytose and kill pathogens in areas of high hemolymph flow.
