Survey of 50 urban households indicates 'luxury effect' among
bugs
California Academy of Sciences
Household insects -- our most overlooked roommates -- are
grabbing the spotlight after centuries in the shadows.
Prior research in the
growing study of life indoors has shown that our homes support a variety of
bugs in the far reaches of cupboard corners and attic alcoves.
Now, researchers
are looking beyond the nooks and crannies to consider the socioeconomic context
of these households.
A team from the California Academy of Sciences, North Carolina State University, and the Natural History Museum of Denmark surveyed the number of different insects in 50 urban homes and determined that wealthier neighborhoods host a greater number of species types than their lower socioeconomic counterparts. The findings are published in the journal Biology Letters.
"The
sheer amount of life thriving within your home -- under carpet, in closets --
is astonishing," says Dr. Misha Leong, lead author and post-doctoral
researcher at the Academy. "Now we're learning that neighborhood affluence
was one of the primary predictors for the number of different bug types --
mostly non-pests -- living inside, which really surprised me. We hope our
findings inspire people to reimagine the context of their homes and apartments
within the larger environment."
Modern
urbanization has greatly influenced the ecological environment, particularly in
terms of the variety and abundance of life that surrounds us.
Aside from urban
variations in climate and environment, this new study points to socioeconomics
as a key player in determining the types of life we find inside our concrete
jungles.
This work suggests that the management of neighborhoods and cities can
have effects on biodiversity that extend from trees and birds all the way to
the bug life in bedrooms and basements.
The luxury effect
Urban
ecologists have been observing how socioeconomics impact species diversity for
nearly two decades.
Previous studies have determined that higher affluence is
frequently associated with more biological diversity across species of plants,
birds, bats, and lizards -- a phenomenon coined the "luxury effect."
Scientists have only recently begun examining the relationship between
socioeconomics and arthropods, a group that includes insects and their close
relatives. Arthropods can have six legs (like moths), eight legs (like
spiders), or sometimes one hundred legs (like centipedes), and fly or wander
from the outside environment into the indoor world.
"The
biodiversity of the indoor environment is still a relatively unexplored area of
research," says Michelle Trautwein, co-author and curator of entomology at
the Academy. "Our houses are really permeable and dynamic. Through our
studies, we hope to inspire citizens all over the globe to get curious about
the species in their everyday lives. We still have so much to learn about
indoor ecology and the ever-evolving relationship between humans and
arthropods."
A hands-and-knees investigation
With
the help of headlamps and knee pads, the research team surveyed 50 urban homes
in Raleigh, North Carolina to collect samples of arthropod species. The
specimens, stored in glass vials for safe transport to the lab, were
painstakingly identified under a microscope to determine the number of
arthropod families represented, indicating overall arthropod diversity in each
household.
Besides
average neighborhood income, the study took into account such factors as the
homes' square footage, size, surrounding vegetation, and more.
Houses tend to
serve as light and bait traps, passively collecting species that find their way
inside from vegetation outside.
The study found that homes in higher income
neighborhoods had higher arthropod diversity. A likely mechanism is that homes
in these neighborhoods host a greater diversity of plants that, in turn,
allowed for a greater variety of plant-loving arthropods to find their way
inside and thrive indoors.
The
scientists found that individual houses without significant plant coverage in
the yard could still support high arthropod diversity when located within more
affluent neighborhoods.
This finding suggests that features such as parks and
communal landscaping that are characteristic of wealthier neighborhoods as well
as lush landscaping choices of neighbors can compensate for local choices of
homeowners.
"Seeing
how these community-wide planning decisions cascade through the neighborhood
and into homes is fascinating," says Leong.
"Besides parks and
communal landscaping, the decisions made at the micro-scale of individual
property owners collectively scales up. This influences the ecological dynamics
within their respective neighborhoods and cities, which can then impact the
biodiversity you find in your bedrooms and basement."
Insects in the great indoors?
"Don't panic"
The
scientists researching indoor arthropods describe home environments as their
own unique, thriving ecosystems. Roughly 100 different species of arthropods
are found inside the average home. One common misconception: the mistaken
belief that most of these species are pests.
"Even
though we spend billions of dollars each year to control for cockroaches,
ticks, termites and other infestations, there are still a number of overlooked,
benign species," says Leong. "Don't panic -- most bugs aren't the
problem roommates we make them out to be."
The
study's authors are traveling the globe to better understand our tiny, closest
companions.
Trautwein, Leong, and their colleagues are in the midst of a
multi-year project sampling arthropods (and collecting face mite samples)
alongside citizen scientists in homes on all seven continents, exploring the
overlooked life that shares our homes and bodies on a daily basis.
Past
expeditions include Sweden, the Peruvian Amazon, and houses in the Academy's
own San Francisco backyard. The scientists will continue collecting
house-dwelling arthropods in Australia, Madagascar, China, and Antarctica
through 2017.
