More than 600 kinds of creepy-crawlies found in American homes

CC BY 2.0 Scanning electron micrograph of dust with dust mites, fur, fibers, and pollen. (Anne A. Madden/Robert Mcgugan/Robin Hacker-Cary)

From mites to cockroaches, our house dust is literally crawling with things.

Little creatures with segmented bodies, many a wiggling jointed leg or limb, and crunchy armored exoskeletons – arthropods, these are the things we share our homes with.

And though that may be cause for shudders, it's pretty much the way it should be. Arthropods comprise the largest animal phylum on the planet, about 85 percent of all known animals in the world are part of this class that includes spiders, insects, centipedes, mites, ticks, lobsters, crabs, shrimp, and scorpions, just to name a few. They’ve been crawling and swimming their way through history long before we showed up on the scene. While we may look at them as invaders in our homes, they would likely (and rightly) feel the same.

While many of the arthropods we share our abodes with are hidden to the naked eye, researchers have long known they’re there. Now in new research from North Carolina State University and the University of Colorado Boulder, scientists have used DNA testing and citizen science to look into the range and diversity of arthropod life in homes across the United States.

"Previous research found a significant diversity of arthropods in homes in one part of North Carolina – we wanted to use advanced DNA sequencing-based approaches to get a snapshot of arthropod diversity in homes across the country," says Anne Madden, a postdoctoral researcher at NC State and lead author of the study. "This work is a significant step toward understanding the ecology of our own homes, with the goal of improving our understanding of how those organisms in our homes may affect our health and quality of life."

In the new study, the team looked at sealed swabs of interior dust sent from 700 households across 48 states. The samples were then subjected to high-throughput DNA analysis to identify every genus of arthropod DNA lingering in the dust.

"We found more than 600 genera of arthropods represented inside people's homes – not including food species, such as crabs and shrimp, which also showed up," Madden says. "That's an incredible range of diversity from just a tiny swab of house dust."

Interestingly, the researchers found several variables that seem to contribute to a wider array of critters – not necessarily more in number, but more in variety: Having cats or dogs in the home; having a home in a rural area; or having a home with a basement.

The researchers have taken the data to create a national atlas, of sorts, for tracking the range of specific arthropod genera across the country. In doing so they can discern things like, for example, that dust mites – which can be vexing allergens in homes – were more common in places that experience higher humidity. They can also now do things like track how specific genera are expanding their range.

"We're just scratching the surface of how we can use this data set and the arthropod atlas," Madden says. "What can it tell us about the food webs in our own homes? What can it tell us about how arthropod populations expand and contract across the country? What emerging allergens can it reveal? We're just getting started.”

And while creeping-crawling things may be that which unnerves you, allergens aside, the real dangers lurking in house dust are the harmful chemicals like phthalates and flame retardants found in 90 percent or more of dust samples. On that note ... be right back, need to dust and vacuum.

More than 600 kinds of creepy-crawlies found in American homes
From mites to cockroaches, our house dust is literally crawling with things.

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