And stay out: Testing how competitive interactions may shape the distribution of Aedes in the Caribbean

Interactions among larval mosquitoes are known to structure patterns of species co-occurrence and shape their distributions across wide geographic areas. Islands in the Caribbean are home to several species of native and invasive mosquitoes in the medically important genus Aedes, however islands differ in their composition, with even close islands possessing different subgroups of mosquito species. Recent work suggests that on the island of Puerto Rico the native mosquito, Aedes mediovittatus (Coquillett) (Diptera: Culicidae), can outcompete the invasive Aedes aegypti (L.) under several resource environments. These competitive interactions may help to explain the disjointed distributions of these species across urban and non-urban habitats. Mysteriously, the highly invasive species, Aedes albopictus (Skuse), is absent from the island, although it invaded other nearby islands (e.g., Hispaniola, Jamaica) decades ago. We conducted a laboratory experiment to test the hypothesis that the superior competitive ability of Ae. mediovittatus over Ae. aegypti also applies to Ae. albopictus, and may help explain the latters’ species absence from the island. Trials were conducted under intra- and interspecific densities crossed with two amounts of two different leaf types serving as detrital resources for developing larvae. Response variables included survival and a composite index of population growth (λʹ). This is the first experiment of its kind to assess if Ae. albopictus island invasion has been thwarted by an established native species of mosquito. The results have implications for our understanding of invasion ecology and biogeography of members of the Aedes mosquito genus.