Unusual Life History Traits of Aedes (Stegomyia) Mosquitoes (Diptera: Culicidae) Inhabiting Nepenthes Pitchers

Unusual life history traits of Aedes (Stegomyia) dybasi Bohart of Palau and Aedes (S.) maehleri Bohart of Yap, Micronesia, were observed in the laboratory. These species are unique in the subgenus Stegomyia in that they use pitchers of a carnivorous plant, Nepenthes mirabilis Druce, as larval habitats. Traits of Ae. dybasi were compared with two sympatric, container-breeding species, Aedes (S.) palauensis Bohart, a probable ancestor of Ae. dybasi, and Aedes (S.) hensilli Farner. Life history traits of Ae. dybasi differ distinctly from those of Ae. palauensis and Ae. hensilli in egg and adult stages as well as in the larva. The female is autogenous and lays a few but extremely large eggs that can neither resist desiccation nor postpone hatch. The latter two species take blood and produce many smaller eggs with desiccation resistance as usual in Stegomyia. Developmental time of eggs was shorter in Ae. dybasi, whereas that for larvae and pupae was longer. Ae. maehleri differs from other Stegomyia species in its early copulation, where males copulate with newly emerging females on the water surface. Females neither are autogenous nor take blood from human hands. Nepenthes pitchers that provide mosquito larvae with a unique environment could contribute to studying either converging or diverging patterns in mosquito evolution under phylogenic potential and constraints after acquisition of a new larval habitat.