Rich Households Have More Diverse Bugs

Mo' money mo' arthropods

spider
In a survey of indoor arthropods, the common house spider (Parasteatoda tepidariorum) was a frequent lodger. Now, the scientists report that richer neighborhoods have a wider variety of arthropods.Bertone et al. (2016)

In wealthy neighborhoods, the houses have a varied palate … of spiders and flies. The interiors of these homes are populated by a more diverse array of arthropods than those in less prosperous neighborhoods, a new study indicates.

The explanation for this bounty actually lies outside the home. Generally, ritzier neighborhoods are also richer in species. Scientists have seen this “luxury effect” before, in plants and outdoor animals such as birds, bats and lizards. For plants, the connection is pretty direct; affluent tenants have more money to spend on landscaping, or live in lusher communities. In turn, a diverse collection of plants offers more food and habitats for animals.

Previously, the team explored 50 houses in and around Raleigh, North Carolina, and determined that more than 100 arthropod species dwell within the average home (most of these tiny occupants aren't pests). Using data from this "arthropods of the great indoors" survey, the scientists have now investigated how landscaping and socioeconomic status can affect indoor bug diversity.

"There is a general perception that homes in poorer neighborhoods harbor more indoor arthropods," the team wrote August 2 in Biology Letters. Their work indicates that this perception is off-base.

Most arthropods that show up inside are actually outdoor species that wandered in by accident. The majority of indoor arthropods were flies, spiders, beetles and ants, although the scientists also unearthed some more human-dependent beasties such as dust mites. Houses in neighborhoods with an average annual income of about $33,000 had denizens from about 74 arthropod families. In neighborhoods with an average yearly income of about $176,000, a given house was likely to carry arthropods from 105 families.

The entomologists expected to find more types of arthropods in big houses with more surrounding plant cover and diversity. But in affluent neighborhoods, even houses with sparse vegetation carried a wide variety of arthropod families; simply being near other, more verdant homes gave them a boost.

Though intriguing, the survey doesn’t represent bug diversity everywhere; the scientists only sampled freestanding houses in one city. But it does show how connected the interiors of our homes are to the world outside. “The management of neighborhoods and cities can have effects on biodiversity that can extend from trees and birds all the way to the arthropod life in bedrooms and basements,” the team concluded.