Study Shows Extensive Biodiversity in Homes Nationwide

Study shows extensive biodiversity in homes nationwide
January 9, 2017

Like it or not, four walls and a roof are not enough to stop nature from taking hold inside. 

Expanding on previous work, biologists from North Carolina State University and the University of Colorado at Boulder have created an atlas of the insects, spiders and crustaceans that live in homes across the United States.

Spider IndoorsThe research, which was published in the journal Molecular Ecology helps to illustrate not only the food webs and ecosystems of American homes, but also how arthropod species, including invasive species, have spread across the United States.

Previous work by the NC State group examined 30 homes in the Raleigh area for arthropod species. Researchers would go room-by-room, scouring every space for insects and spiders. They discovered dozens to hundreds of different species in each home, totaling more than 500, but all of that fastidious searching required too much time to do the same sort of study on a national scale.

For this study, citizen scientists from around the country took swabs of dust from the top of doors inside their homes. The researchers ran DNA analyses on the dust samples to pick up on every genus—a group of closely related species—of arthropod found in the homes.

They discovered 600 genera of arthropods in more than 700 U.S. homes. And if you are wondering how much researchers can actually pick up based on DNA from the top of a door, Anne Madden, lead author of the study and postdoctoral researcher at NC State said they picked up on crab and shrimp DNA in multiple homes from when people brought them home for dinner.

Dust MiteThe data came from all 48 contiguous states, allowing Madden and her colleagues to pick up on trends of where to find specific insects, how they migrate across the country and what features of a home are more conducive to specific insects.

According to the Asthma and Allergy Foundation of America, allergic rhinitis—indoor and outdoor allergies—affected 17.6 million American adults and 6.6 million children in 2012. Dust mites are a major cause of year-round allergies, so any trends in which they appear could help inform homeowners about when to take extra steps to clean out dust mites. The researchers found dust mites in the more humid environments of the coasts and Mississippi River region but not in the Great Plains, Rocky Mountains or desert regions.

The researchers also found other factors that influence how many different species of bugs find their way inside. Houses in rural areas contained more genera of bugs. So did houses with basements. Having a dog or a cat also tended to increase the diversity of arthropod species.

Studies like this one help to demonstrate that inside or outside, we are part of an ecosystem, and we share space with organisms of all types. Learning more about the home biome can help keep everything in it healthy, as well as teach us more about what is going on outside.

If you would like to take part in a citizen science project, Your Wild Life, the NC State group that conducted this research and studies the ecosystems of homes and human bodies, conducts many similar studies. You can learn more about them and participate by clicking here.

—Daniel Lane

Daniel Lane covers science, medicine, engineering and the environment in North Carolina.

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