http://www.sciencedaily.com/images/2008/03/080317123243-large.jpg
Their gentle nature, large
size, odd sounds and low-maintenance care have made Madagascar hissing cockroaches
popular educational tools and pets for years. But the giant insects also have
one unfortunate characteristic: Their hard bodies and feces are home to many
mold species that could be triggering allergies in the kids and adults who
handle the bugs. (Credit: Image courtesy of Ohio State University)
ScienceDaily (Mar. 18, 2008)
— Their gentle nature, large size, odd sounds and low-maintenance care have
made Madagascar hissing cockroaches popular educational tools and pets for
years. But the giant insects also have one unfortunate characteristic: Their
hard bodies and feces are home to many mold species that could be triggering
allergies in the kids and adults who handle the bugs, according to a new study.
Researchers have identified 14 different types of
mold on and around this species of cockroach, including several molds
associated with allergies and others that can cause secondary infections if
they enter the lungs or an open wound.
“This is mainly a point of public awareness,”
said Joshua Benoit, lead author of the study and a doctoral candidate in
entomology at Ohio State University. “We are not criticizing their use. We are
just saying that if you handle these cockroaches, you should wash your hands
when you’re done.
“It’s also best to maintain the cage. It’s not a
pet you can ignore,” he said. “Without regular cleaning, feces will build up,
and the old exoskeletons they shed will build up. And that’s where a lot of the
problems happen.”
The natural life of the Madagascar hissing
cockroach, or Gromphadorhina portentosa, is not well understood. But in
captivity, the insects thrive on dog food and fruit, reproduce plentifully and
do not bite. They grow to between 2 and 3 inches long and 1 inch wide, and will
make their characteristic hissing sound if they are squeezed or otherwise feel
threatened.
Benoit, an allergy sufferer himself, suspected
the insects’ large bodies and moist living environments might combine to create
a prime breeding ground for mold.
Some people are allergic to the species of
cockroaches that are household pests. In those cases, the bugs’ actual bodies
contain allergens. In the case of the Madagascar hissing cockroaches, the most
potent mold allergens live on and around the insects instead.
Benoit and colleagues examined the insects from
an Ohio State-based colony as well as those found in home collections, zoos,
pet stores and science classrooms across Ohio.
The research group tested the feces first, and,
as expected, found mold in the bugs’ waste. Then the team examined the giant
cockroaches themselves, both outside and inside their bodies, to see what other
allergens might be present.
The most commonly found mold species found on the
body surfaces of young and adult Madagascar hissing cockroaches were Rhizopus,
Penicillium, Mucor, Trichoderma and Alternaria, several of which are listed by
the Centers for Disease Control and Prevention (CDC) as common indoor molds.
Colonies of the mold species Aspergillus niger, a common contaminant of food,
were particularly plentiful in the feces and external shells that had been
discarded as the insects molted.
Few molds were found inside the cockroaches’
bodies.
Molds are fungi that grow best in humid
conditions, and spread and reproduce by making spores. Benoit said all of the
mold species found on and around the hissing cockroaches are capable of
producing huge quantities of spores. And the spores themselves can get on bug
handlers’ skin or be inhaled, triggering allergic responses in those sensitive
to the molds.
For people who are allergic to molds, exposure
can cause symptoms such as nasal stuffiness, itchy or burning eyes, wheezing or
skin irritation, according to the CDC. Some people with serious allergies to
molds may have more severe reactions.
Benoit now is pursuing additional studies on one
surprise among the findings: Symbiotic mites also live on the cockroaches, and
help keep them clean.
“The mites sweep the surface and remove old food
particles and debris, so they remove places on which fungi can grow,” Benoit
said.
The research is published in the March issue of
the journal Mycoses. Benoit conducted the project with Jay Yoder and Brian
Glenn of Wittenberg University and Lawrence Zettler of Illinois College.
http://www.sciencedaily.com/releases/2008/03/080317123243.htm
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