Welcome to the club? Assessing the competitive ability of a new mosquito invader, Culex coronator, across diverse resource environments

Background/Question/Methods

Successful range expansion by species into new locations is often the result of the ability to outcompete residents or to occupy otherwise empty niche space; associations with humans can facilitate the speed of expansion. The mosquito Culex coronator (CC) has undergone rapid range expansion since 2002, with its historical distribution in the southwestern U.S. expanding eastward to the Atlantic coast. Although CC nominally  uses small natural aquatic habitats for reproduction, the use of containers (e.g., vehicle tires) in its native range and elsewhere makes it potentially important as a tire invasive and container use may be a mechanism for rapid expansion. To determine the potential ecological effects of CC on resident species we conducted a laboratory experiment to assess the competitive ability of CC with the two most common tire-inhabiting species in Mississippi, Aedes albopictus (Asian tiger mosquito, AA) and Culex quinquefasciatus (Southern house mosquito, CQ). We grew larvae under a factorial design with each species alone (CC, AA, CQ) and in combination (CC+AA, CC+AQ) across three different resource environments (leaf detritus only, animal detritus only, and a mixture of types);  resources reflected the detritus-based nature of containers. We then assessed mosquito performance via survival, adult female mass and development time of each species across detritus environments. Mass and development time were analyzed for each species, separately, using multivariate analysis of variance with detritus type and species combination as factors. Survival was analyzed using ANOVA for each species, separately.

Results/Conclusions

When grown alone, female CC developed fastest in treatment levels that contained animal detritus alone or in combination with leaves, but development became longer when in combination with AA in animal only environments. There were no differences in performance across detritus environments for CC when grown with CQ, nor did CQ vary in mass or development times when grown with CC compared to when grown alone. Adding CC to AA did result in a 14% decrease in mass of female AA. Survival for CC was affected by both detritus type (lowest in leaves only compared to animal treatment levels) and species combination (lowest with AA compared to alone or with CQ). These finding suggest that Culex coronator may be ecologically equivalent to C. quinquefasciatus, but its performance suffers in the presence of Aedes albopictus in some resource environments. Thus, we suggest that the establishment of C. coronator is possible if the proclivity of this species to use container habitats continues.