Mosquito species composition and abundance along an urban to rural gradient in Baltimore MD

Background/Question/Methods

In 2014 the mosquito-borne virus Chikungunya swept through the Caribbean, affecting hundreds of thousands of locals and travelers in the area. By the end of July 2014, Florida had reported the country's first locally acquired cases of the disease. Aedes albopictus and Aedes aegpti have been implicated as the major vector species, and historically have been responsible for large outbreaks of the virus. Ae. albopictus is a highly invasive species in the United States, with established populations in Baltimore City, MD. This container breeding species is not only a nuisance due to its aggressive feeding behaviors; it also poses a real disease risk in urban areas with human-dominated ecosystems. We evaluated the difference in mosquito species composition and abundance, with an emphasis on Ae. albopictus, along a gradient from high-density urban habitat, to rural forested habitat. From 2011-2014, ovitraps were deployed to sites in Baltimore City and in rural Baltimore County. Each week collected mosquito larvae were enumerated and identified to species.

Results/Conclusions

The data demonstrates substantial inter and intra-annual variation in local mosquito species phenology, which may relate to difference in weather but may also be due to shifts in the invasive species composition.  Results show more diverse mosquito communities in rural, forested sites which have relatively even population abundance across species. In contrast, urban sites not only had fewer mosquito species, these communities were dominated by the invasive and human biting mosquitoes Ae. albopictus, Ae. aegypti, Culex pipiens, and  more recently Ae. japonicus. Furthermore, mosquito vector species sampled from urban sites reached higher peak abundance and did so early in the season.  Our work provides insight to breeding habits of mosquito species found in urban environments. Not only could this knowledge help implement mosquito management plans in cities, but could also help assess disease risk of emerging mosquito vectored diseases.