Challenging Popular Belief, Mosquito Larvae Breathe Underwater

Simple Summary: We present the first simultaneous quantitative analysis of mosquito larval respiration in air and water, revealing the unknown ability of the larvae of the most cosmopolitan (Aedes aegypti) and the most invasive (Aedes albopictus) disease vectors to breathe underwater. Immature mosquitoes are thought to breathe only atmospheric air through their siphons despite reports of prolonged submerged survival. We studied the survival of last-instar larvae of Aedes aegypti fully submerged at different temperatures and measured the oxygen consumption from air and water-dissolved larvae and pupae of this species under different conditions. Larvae survived much longer than expected, reaching 50% mortality only after 58, 10, and 5 days at 15 degrees, 25 degrees, and 35 degrees C, respectively. Larval to pupa molt was only observed in larvae with access to air, whereas individuals kept submerged never molted. Although most of the oxygen was obtained from the air, larvae obtained 12.72% of their oxygen from the water, while pupae took only 5.32%. In both media, temperature affected the respiration rate of the larvae, with relatively close Q(10) values (1.56 and 1.83 for water and air, respectively). A similar pattern of O-2 consumption was observed in Ae. albopictus, whose larvae obtained 12.14% of their oxygen from the water. The detailed quantification of oxygen consumption by mosquito larvae showed that water-dissolved oxygen is not negligible and physiologically relevant, challenging the idea that mosquito larvae only breathe atmospheric oxygen.