Fig 6. Mosquito vectors egglaying behavior and water flux through the eggshell before and after serosal cuticle formation.

From top to bottom, leftmost panel: while Ae. aegypti and An. aquasalis females lay their eggs individually, the females of Cx. quinquefasciatus lay their eggs as an organized raft that floats on the water surface. In all species, before serosal cuticle formation water passes freely through the eggshell. Serosal cuticle formation diminished water passage through the eggshell in a color-dependent manner: while in Ae. aegypti, with a black endochorion, most of the water is retained inside the egg, in An. aquasalis, with a dark-brown endochorion, some of the water is retained inside the egg, but not all. Finally, in Cx. quinquefasciatus, with a light-brown/light-tanned endochorion, most of the water escapes and only a small portion of it is retained inside the egg. The depicted embryonic morphology are representative for each stage and species [19] and egg sizes among species are depicted in their natural proportion [20]. For the sake of simplicity, the outermost eggshell layer (the exochorion) and the other extraembryonic membrane (the amnion) are not depicted here. The exochorion does not participate in the ERD [20].