Apple snails and tiger mosquitoes: A curious association between two invasive species in Florida, USA

Apple snails (Pomacea insularum) and Asian tiger mosquitoes (Aedes albopictus) are among the most invasive species on the planet, as ecosystem disruptors and hosts/vectors of human pathogens. In Florida, USA, where these species are sympatric invaders, tiger mosquitoes were found to commonly exploit the discarded shells of apple snails as breeding sites (nearly a quarter of all shells examined harbored mosquito larvae). The number of larvae per shell could also be quite large (up to 56 larvae/pupae from a single shell). Calculations based on field data suggest that invasive apple snail shells contribute 1.63 mosquitoes per meter of riverbank, equaling roughly 150,000 mosquitoes along the length of the Hillsborough River (9.5 km). These two super-invaders, originally from different continents, have no known interactions in life, yet where both species have invaded, the shells of dead snails are exploited by Asian tiger mosquitoes as breeding sites, amplifying the invasive potential of this incredibly adaptable vector. No other mosquito species were found to breed in apple snail shells, demonstrating the unique adaptive ability of this vector mosquito. Whether or not Asian tiger mosquitoes utilize shells of apple snails in other regions or if shells of other apple snail species, including the native Florida apple snail, contribute to mosquito breeding is not known.